Cascadia Research


Executive Summaries of Technical Reports and Publications (partial list primarily of older reports)


Calambokidis, J., T. Chandler, E. Falcone, and A. Douglas. 2004. Research on large whales off California, Oregon, and Washington: Annual report for 2003.  Final report to Southwest Fisheries Science Center, La Jolla, CA.  Cascadia Research, 218½ W Fourth Ave., Olympia, WA  98501.  48pp  Click here to view full report

This report summarizes fieldwork conducted by Cascadia Research and collaborators in 2003 on humpback, blue, fin and gray whales off California, Oregon, and Washington and also summarizes work conducted under NMFS permit #540-1502-00 in 2003. Principal support for this research was from Southwest Fisheries Science Center to assess population size and trends (Contract # 50ABNF100065) with additional support from Office of Naval Research, Office of Naval Operations, National Marine Mammal Laboratory, and the Olympic Coast National Marine Sanctuary.

Identification photographs in 2003 came from a number of sources and survey types including 65 days of dedicated research surveys under Permit 540-1502-00 conducted by Cascadia Research off California, Oregon, and Washington. Photographic identification was also conducted on either an opportunistic basis by others who provided photographs to Cascadia or as part of collaborative research under other permits.

 A total of 542 humpback whale identifications were obtained in all effort off California, Oregon, and Washington in 2003 representing 398 unique individuals. Of the 398 identified whales, 98 were seen two or more times during the year. Rates of interchange of animals were highest among adjacent years and decreased progressively with distance to the north or south. Abundance estimates of humpback whales from mark-recapture revealed a surprising jump to 1,391, about 400 animals higher than any previous estimate. Estimates of humpback abundance along the west coast from our previous work had revealed a steady increase in abundance of about 8% per year through 1998, after which there was a dramatic drop in abundance. The current high estimates appear to be the result of an influx of whales into the region that had not been seen in previous years.

Blue whale identifications were made from southern California to British Columbia in 2003 with 534 identifications of 292 unique individuals in 2003. Movements of blue whales within 2003 were fairly extensive; animals were resighted all along the California coast in 2003. A single blue whale identified off the southwest end of the Queen Charlotte Islands, British Columbia on 7 August 2003 was an animal that had been seen eight times from 1988 to 2001 off California. This is the second animal identified off British Columbia with both matching identifications off California. The only previous whale identified off British Columbia was ID# 1110, seen on 12 June 1997 and then resighted on 1 and 14 July in the Santa Barbara Channel. While 2003 data did not directly contribute to a new estimate of blue whale abundance, we were able to update our most recent estimate from mark recapture to 1,781 blue whales for 2000 to 2002.

Tagging in 2003 consisted of 41 deployments of four instrument packages on blue, fin, and humpback whales. The vast majority of the tag deployments in 2003 were of the Burgess acoustic tag. Deployments in Monterey Bay were conducted in collaboration with Scripps Institute of Oceanography, Moss Landing Marine Labs, and UC Santa Cruz and yielded dive data in conjunction with hydro-acoustic mapping of prey fields. Combined dive, pitch, and roll data from the Burgess tags have provided insights into the diving dynamics of blue whales. These tags have also contributed insights into the vocal behavior of blue whales including indications that it is only the males that produce the long loud repeated calls generally described for blue whales but that both sexes produce the shorter more variable D-type call. Satellite tag data for the five humpback and two blue whales provided movement data on both species over only about a 2-week period.

A total of 97 skin samples were collected off California, Oregon, and Washington in 2003 under our permit. Of these, 71 were from biopsies and 26 were small pieces of skin collected from the suction-cups and other parts of the tagging apparatus. Skin samples were collected from 40 fin whales, 28 blue whales, 21 humpback whales, and 8 gray whales.

Reaction of whales to the various research activities was generally mild. Most animals that were approached for photographic identification did not exhibit any detectable behavioral reaction to the boat. A total of 51 whales were approached to attach tags and these close approaches for tagging generally resulted in some reaction from the whales, which appeared to be from the close approach of the boat. The most typical response was a suspension of the surface series (where the animal would resurface after a slightly longer surface interval) or a termination of the surface series. There were 103 approaches of animals to obtain a biopsy; a clear reaction to either the approach or the biopsy was seen in slightly less than half of these instances. Reactions were most common to biopsy hits than to misses and humpback whales showed observable reactions at a much higher rate than blue or fin whales.

Calambokidis, J., T. Chandler, L. Schlender, G.H. Steiger, and A. Douglas. 2003. Research on humpback and blue whales off California, Oregon, and Washington in 2002.  Final report to Southwest Fisheries Science Center, La Jolla, CA.  Cascadia Research, 218½ W Fourth Ave., Olympia, WA  98501.  47pp. Click here to view full report

Cascadia Research continued a long-term research effort on humpback and blue whales off California, Oregon, and Washington in 2002. The research had a number of components with the overall purpose to examine distribution, abundance, movements, and population dynamics of humpback and blue whales in the eastern North Pacific using photographic identification of individual animals. Also included in the effort in 2002 was monitoring underwater behavior and vocalizations of blue whales as part of a cooperative research effort with Scripps Institution of Oceanography, National Geographic and Office of Naval Research.

Identification photographs were taken from a number of platforms and collaborators. Cascadia Research conducted 89 days of effort totaling 798 hours and 6,352 nmi from small boats. Additional identifications photographs were obtained by: 1) SWFSC scientists during the outbound leg of a cruise headed off California, 2) by the naturalists from the Channel Islands National Marine Sanctuary’s Whale Corps opportunistically as a part of whale-watching trips in the Santa Barbara Channel, 4) by Peggy Stapp and Nancy Black opportunistically from whale-watch boats in Monterey Bay, and 5) as part of some surveys conducted by the Olympic Coast National Marine Sanctuary off northern Washington. In total, suitable identification photographs of blue whales were made on 530 occasions representing 312 unique whales, one of our highest annual totals. Humpback whales were identified on 529 occasions representing 347 unique individuals.

Estimates of humpback whale abundance using a number of mark-recapture models revealed an increase in abundance of humpback whales from the past two years with 2001-2002 estimate of 1,034 (CV=0.11). This is an increase from the previous two estimates (1999-2001) that were under 800. Humpback whale abundance had steadily increased from the early to the late 1990s at a rate of about 9% per year. Some time between 1998 and 1999 there had been a drop of 25% in our estimates of abundance. Because our most recent abundance estimate represents a larger increase from previous years than would possible by population growth alone, it suggests either the drop in the late 1990s may not have been as large as originally estimated or the current estimate may be high due to chance or bias.

We were able to obtain a more accurate updated blue whale abundance estimate incorporating the 2002 data. The pooled sample from 2000 to 2002 of the systematic and coastal samples was adequate to estimate abundance with a similar level of confidence as in past years. Estimates for 2000-2002 for right and left sides were 1,567 (CV=0.32) and 1,953 (CV=0.33), respectively, averaging 1,760. This is slightly lower than estimates from 1991-93 and 1995-97 using similar procedures. While these estimates are not significantly different from those in the early and mid-1990s, they do not suggest that blue whale populations have been increasing over the last decade has was the case with humpback whales.

Tagging efforts in 2002 resulted in successful suction-cup attachment of three types of tags on blue whales (National Geographic’s Crittercam, Bill Burgess’s bio-probe acoustic tag, and WHOI’s dTag). One extended deployment provided more than 15 hours of dive data through the evening and night. Underwater vocalizations by the tagged or adjacent animals were documented on three deployments (one of each tag type).


Calambokidis, J., R. Lumper, M. Gosho, P. Gearin, J.D. Darling, W. Megill, , D. Goley, B. Gisborne, and B. Kopach. 2003. Gray whale photographic identification in 2002: Collaborative research in the Pacific Northwest. Report to the National Marine Mammal Laboratory, Seattle, WA. Cascadia Research, 218½ W Fourth Ave., Olympia, WA  98501.  19pp. Click here to view full report

Since 1998, there has been a collaborative effort among a number of research groups conducting photographic identification of gray whales in the Pacific Northwest (Calambokidis et al. 2000,  2002a, 2002b). This reports summarizes field effort conducted by Cascadia Research in 2002 for gray whales and the results of the photographic comparison from this effort as well as that from field work conducted by the National Marine Mammal Laboratory (NMML), University of Victoria, West Coast Whale Research Foundation, the Marine Mammal Education and Research Program (MMERP) at Humboldt State University, Coastal Ecosystems Research Foundation, and the operator of the Juan de Fuca Express (a coastal ferry service). The field effort reported and these comparisons were conducted under contract to NMML.


Chandler, T., and J. Calambokidis. 2003. 2003 aerial surveys for harbor porpoise and other marine mammals off Oregon, Washington, and British Columbia. Contract report to National Marine Mammal Laboratory, Seattle, WA. 25pp Click here to view PDF of full report

From 1 - 31 August 2003, Cascadia Research conducted aerial surveys for harbor porpoise, Phocoena phocoena, and other marine mammals under contract from the National Marine Mammal Laboratory.  This was the second year that surveys were flown over the coastal waters of Washington and southern British Columbia and the inland waters of Washington (except Puget Sound) and southern British Columbia as part of a multi-year abundance estimate effort. This report summarizes the effort undertaken and sighting results of the second year. 

The survey design was identical to the first year but included a smaller set of survey strata that did not include the Oregon and southern Washington outer coasts.  As opposed to 11 regions or strata (A-K) as in 2002, there were 6 regions flown this year (F-K) with each containing several modified sawtooth line-transect routes. Two of the three coastal strata were further divided into inshore and offshore components with the offshore tracklines fewer in number.  A high-wing twin-engine aircraft fitted with side bubble windows and a belly window was used with three experienced observers and a dedicated data recorder.  A Data Acquisition System (DAS) interfaced with a GPS was used to streamline the data recording/entry process.   Flights were conducted primarily on days with ‘good’ conditions (Beaufort sea state of 0-2, and cloud cover 50% or less). Sections flown in conditions worse than this were re-flown if possible.   

 The primary objectives of this study were to: 

1)     conduct line-transect aerial surveys off  Washington  and British Columbia to obtain data to estimate abundance of harbor porpoise.

2)     obtain data on other species of marine mammals in these areas.

3)     conduct aerial surveys in the eastern Strait of Juan de Fuca and the San Juan Islands concurrently with small boat transects in the same area.

A total of 74.5 hours were flown in the study area including transits to and from the various regions. Of these hours, 28.2 were flown on-effort covering 2,717 nmi. A total of 80% of this (22.5 h and 2,169 nmi) were conducted in ‘good’ weather conditions. Survey coverage was fairly complete in most of the six regions except northern Washington. Although heavily targeted this year due to missed effort last year, the northern Washington outer coast again proved hard to cover mostly due to fog and cloud cover but also high winds.

A total of 1,664 sightings of 4,166 animals were made both on and off effort. These represented 3 baleen whale species, 2 delphinid species, 2 porpoise species, 5 pinniped species, and 1 fissiped species. Sightings of harbor porpoise (499 sightings of 847 animals) and harbor seals (1048 sightings of 2,994 animals) together accounted for 92% of the sightings. Harbor porpoise were seen in all regions (422 sightings of 716 animals on-effort in ‘good’ weather). High concentrations of harbor porpoise were seen in the central Strait of Juan de Fuca (in conjunction with vessel surveys) and also in the northern San Juan Islands. Relatively low numbers of sightings were made in central and northern Strait of Georgia.


Chandler, T., and J. Calambokidis. 2003. 2002 aerial surveys for harbor porpoise and other marine mammals off Oregon, Washington, and British Columbia. Contract report to National Marine Mammal Laboratory, Seattle, WA. 25pp Click here to view PDF of full report

From 6 August to 12 September 2002, Cascadia Research conducted aerial surveys for harbor porpoise, Phocoena phocoena and other marine mammals under contract from the National Marine Mammal Laboratory.  The surveys were flown over the coastal waters of Oregon, Washington, and southern British Columbia and the inland waters of Washington (except Puget Sound) and Southern British Columbia as part of a multi-year abundance estimate effort.   This report summarizes the effort undertaken and sighting results of this first year. 

The survey area was divided into 11 strata (A-K) with each containing several modified sawtooth line-transect routes. Most (5) of the coastal strata were further divided into inshore and offshore components with the offshore tracklines fewer in number. A high wing twin engine aircraft fitted with side bubble windows and a belly window was used with three experienced observers and a dedicated data recorder.  A Data Acquisition System (DAS) interfaced with a GPS was used to streamline the data recording/entry process.   Flights were conducted primarily on days with ‘good’ conditions (Beaufort sea state of 0-2, and cloud cover 50% or less). Sections flown in conditions worse than this were re-flown if possible..   

The primary objectives of this study were to: 

1)    Conduct line-transect aerial surveys off Oregon, Washington, and British Columbia to obtain data to estimate abundance of harbor porpoise

2)    Obtain data on other species of marine mammals in these areas

3)    Conduct aerial surveys in the eastern Strait of Juan de Fuca and the San Juan Islands concurrently with small boat transects in the same area.

A total of 111 hours were flown (not including ferry of the aircraft from Oxnard, California). Of these 42.6 hours were flown on-effort covering 4,010 nmi. A total of 86% of this (36.5 h and 3,434 nmi) were conducted in ‘good’ weather conditions. Surveys coverage was fairly complete in most of the 11 regions except northern Washington. Off northern Washington, permit conditions to avoid impacts on eagles and cormorants prevented flights early in the survey period and poor weather prevented most flights later in the survey period.

A total of 1,696 sightings of 4,765 animals were made both on and off effort. These represented 5 baleen whale species, 4 delphinid species, 2 porpoise species, 5 pinniped species, and 2 otters. Sightings of harbor porpoise (607 sightings of 935 animals) and harbor seals (806 sightings of 2,823 animals) together accounted for 83% of the sightings. Harbor porpoise were seen in all regions (536 sightings of 836 animals on-effort in ‘good’ weather). High concentrations of harbor porpoise were seen in the central Strait of Juan de Fuca (in conjunction with vessel surveys) and also in the northern San Juan Islands. Relatively low numbers of sightings were made in central and northern Strait of Georgia.


Rasmussen, K., J. Calambokidis, and G.H. Steiger. 2002. Humpback whales and other marine mammals off Costa Rica and surrounding waters, 1996-2002. Report of the Oceanic Society 2002 field season in cooperation with Elderhostel volunteers. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 32pp. Click here to view full report

Since 1996, Cascadia Research has been conducting research on humpback whales and other marine mammals off the Pacific coast of Costa Rica and surrounding areas of Central America. The principal objectives are to examine aspects of humpback whale use of Central America including, the number, habitat preference, timing, behavior and migrations of humpback whales as well as document the occurrence of other marine mammals species.

The research has been conducted in collaboration with the Oceanic Society and with Elderhostel volunteer support. Small boat surveys  from 1996-2002 were conducted primarily from Drake Bay on the north side of the Osa Peninsula, Costa Rica. Surveys were also conducted off of northern Costa Rica in 1999-2002, and off Panama in 2001-2002. All humpback whales seen were approached to obtain identification photographs of individual animals. Acoustic monitoring and recording for humpback song was conducted as an integral part of the visual surveys. Four aerial surveys were conducted in 2002 covering the entire Pacific coast of Costa Rica, and the western Pacific coast of Panama.

Humpback whales were consistently sighted in all years off southern Costa Rica, most whales found between the mainland and Canos Island where our principal survey effort was concentrated. Our success in finding whales in surveys off northern Costa Rica and Panama was more variable. The overall group composition for humpback whales off Costa Rica is not very different than has been reported in other wintering areas and included singles, cows with calves, and occasionally larger surface-active groups.

With the effort in 2002, 81 different individual humpback whales that has been identified off Central America (including S. Mexico to Panama) in winter months. Of these, 69 (85%) have been also seen off California, a match rate that indicates these whales exclusively migrate from the California feeding aggregation. This overall rate is higher than has been documented between any other winter and feeding regions that scientists have examined. whales feeding off southern California were more likely to migrate to Central America than those feeding of northern California, Oregon, and Washington. The longest migration documented was from Newport, Oregon, to Costa Rica (5,524 km) and the shortest documented transit was 56 days.

Since 2001, we have also begun to study the presence of humpback whales off of Costa Rica and Panama during the southern hemisphere wintering season (Northern Hemisphere summer). Of the 25 individuals identified off of Costa Rica and Panama during this season, three have also been identified feeding off the Antarctic Peninsula. This is the first documented migration between hemispheres and  sets a new record for the longest migration by an individual mammal (8,400 km each way). We also documented sightings of 10 other marine mammals species besides humpback whales in our surveys. Spotted and bottlenose dolphins were the most common other species encountered. The increased tourism and other development in these regions makes it critical to document the occurrence of marine mammals and identify potential threats.


Calambokidis, J., T. Chandler, L. Schlender, K. Rasmussen, and G.H. Steiger. 2002. Research on humpback and blue whales off California, Oregon, and Washington in 2001.  Final report to Southwest Fisheries Science Center, La Jolla, CA.  Cascadia Research, 218½ W Fourth Ave., Olympia, WA  98501.  50pp Click here to view full report

Cascadia Research conducted research on humpback and blue whales off California, Oregon, and Washington in 2001. The primary purpose of the research has been to examine distribution, abundance, movements, and population dynamics of humpback and blue whales in the eastern North Pacific using photographic identification of individual animals.

Photographic identification was primarily conducted from small boats on 63 days of totaling 522 hours on the water. Additional, photo-ID was conducted from SWFSC’s ORCAWALE cruise off California, Oregon, and Washington, during surveys based from the Scripps vessel Sproul, and opportunistically from whale-watch boats. Suitable identification photographs of blue whales were made on 539 occasions representing 274 unique whales, one of our highest annual totals. Identifications of humpback whales were made on 541 occasions representing 311 unique individuals.

Estimates of humpback whale abundance using a number of mark-recapture models indicated abundance had declined starting in the late 1990s. After a high of just over 1000 whales in the late 1990s, the current estimate shoes a decline to 779 whales. The reduction appears to have occurred as a result of an elevated mortality (or emigration) rate. There has not been any indication of decreased number of calves in the population or increased number of strandings. The cause for this decline is not clear but appears to coincide with the timing of the severe 1997-98 El Nino. While the population does not appear to have recovered to pre-whaling numbers, there have been indications of declines in plankton and zooplankton-feeding seabirds off California in the 1980s and 1990s and may be lowering the carrying capacity for humpback whales.

Blue whale abundances could not be accurately estimated from the 2001 samples because relatively few blue whales were encountered and identified during the systematic SWFSC surveys. The identifications from these surveys provide an essential representative sample of blue whales in both inshore and offshore waters. Estimates made using the 2001 data yielded an abundance of only about 1,000 blue whales, well below the numbers estimated obtained from previous surveys. The small number of identifications obtained from the 2001 systematic surveys, however, result in these estimates having a high level of imprecision.

Tagging efforts in 2001 resulted in successful suction-cup attachment of two types of tags on blue whales. Crittercam deployments yielded information on feeding and diving behavior of blue whales off southern California. Data and video images from these deployments of San Miguel and San Nicolas Island showed blue whales feeding down to 300 m on extremely dense layers of krill. Additional short test deployments were made of a new acoustic-recording tag.


Calambokidis, J. 2002. Underwater Behavior of Blue Whales Using a Suction-cup Attached CRITTERCAM. Final Technical Report to Office of Naval Research for Grant Number: N00014-00-1-0942. 7pp Click here to view full report

We deployed an instrument package developed by National Geographic (CRITTERCAM) on blue whales at three locations and time periods to examine their underwater behavior. Deployments were conducted in Monterey Bay, southern California Bight, and Sea of Cortez, Mexico. In total, 17 deployments were made, with 8 deployments and recoveries of 15 min to over 6 h. We have developed more effective approaches resulting in an increased success rate in attaching tags, and improved the performance of the Crittercams themselves. Deployments have revealed that: 1) whales were feeding by conducting multiple upward lunges into prey, 2) whales were coming into the krill layer from below and then inverting, 3) lunges brought the whales to near stand-still within dense layers of krill, 4) blue whales were diving deeper (300 m) than had previously been reported, 5) most animals were not vocalizing during feeding, and 6) there did not appear to be close spacing or coordination between pairs of whales.


Calambokidis, J., T. Chandler, and A. Douglas. 2002. Marine mammal observations and mitigation associated with USGS seismic-reflection surveys in the Santa Barbara Channel 2002. Report to U.S. Geological Survey, Menlo Park, CA. Cascadia Research, 218½ W Fourth Ave., Olympia, WA  98501.  30pp Click here to view full report

From 14 to 28 June 2002, the U.S. Geological Survey conducted seismic-reflection surveys in the Santa Barbara Channel area off of southern California. As a part of this project, Cascadia Research was contracted by the USGS to monitor marine mammals from the survey platform and provide mitigation on impacts on marine mammals by requesting shutdown of the sound sources when marine mammals were close to the operations. This report summarizes the results of the marine mammal mitigation and monitoring program conducted in conjunction with this USGS surveys. In addition to mitigating from the survey ship there was an effort to tag large whales ahead of the research vessel and monitor both their behavior and the levels of sound received by the animal from the survey vessel. 

 A small two-chamber generator-injector (GI) airgun was used during daylight hours only. The GI gun of the size we used has a sound-pressure level (SPL) of about 220 dB re 1 µPa-m RMS with a sound pulse duration of 10 ms. Problems with the airgun on 22 June required that it primarily be used with only a sleeved single chamber. This reduced capacity from 70 in3 down to 24 in3 and reduced pressure (3000psi to 2000psi). Other lower-power sound sources were also used including a high-resolution Huntec™ boomer system, an Edgetech 512i Chirp sub-bottom profiler, and a minisparker. Two sets of safety zones were used, one for the airgun and a smaller one when only the lower power sound sources were in use.

 The primary objectives of the marine mammal study were to: 1) help mitigate impacts on marine mammals by providing immediate information on the presence of any marine mammals close enough to the sound source to risk injury so that the sound source can be turned off, 2) document the presence and number of marine mammals present in the vicinity of USGS survey operations, and 3) document reactions of marine mammals to the survey ship and sound sources. We also had secondary objectives to attach tags to blue and humpback whales in the vicinity of the seismic-reflection survey as well as examine changes in distribution of whales in reaction to the passage of the survey vessel.

 The research effort was primarily conducted directly from the seismic-reflection survey vessel (Auriga).  Observers conducted 24-hour-a-day observations from the survey ship during all seismic-reflection operations. There was a total of 289.3 hours of observation during day and night in the study area including 85.7 hours of observation while the airgun was firing.

 The mammal observers requested shut-down of sound source operations for marine mammals 83 times, 64 during the day and 19 at night. A total of 38 shutdowns called while the airgun was in operation (termed high power) and 45 shutdowns occurred while the airgun was not in use but one of the other low power sources were in use. The principal species triggering shut-downs (45%) were common dolphins. Observers made 504 sightings of 6,537 marine mammals representing 11 species over the course of the survey. California sea lions were the most common followed by common dolphins and humpback whales. Marine mammals were observed exhibiting a variety of behaviors during the period of observation with no clear indication of distress or problems related to sound source operation. Animals tended to be oriented away from the ship more often than toward the ship in all types of operation modes.

We deployed suction-cup attached tags with acoustic recorders to blue and humpback whales in the general vicinity as the seismic-survey operations. Unfortunately it proved difficult to opportunistically get these tags on animals directly ahead of the path of the survey ship. Despite these problems we did place tags on several animals within a few km of the ship while the ship was operating the single-chamber airgun. While these tag deployments did not allow an evaluation of changes in whale behavior in response to specific received sound levels from the Auriga, we did obtain useful data on whale behavior and the tags on two occasions obtained recordings of the airgun in the distance.

We were able to evaluate any changes in blue whale distribution in response to the single-chamber airgun on one day where we conducted repeated transects with a 2nd vessel through an area of blue whale concentration before, during, and after passage of the survey vessel. These did not indicate any dramatic shift in blue whales away from the area where the ship operated.

There has been heightened concern in recent years about the potential impacts of underwater sounds on marine mammals. This concern has been heightened by recent evidence of strandings of marine mammals in relation to operation of mid-frequency sound sources by the military. In 2002, the stranding of several beaked whales was documented in the Sea of Cortez in close proximity to operation of a large air-gun array. The sound sources involved in the current study were dramatically smaller (less than 100 in3 compared to several thousand in3). While animals seemed to orient away from the survey vessel and in general were sighted farther away when the airgun was firing, we did not see any signs of distress or shifts in overall distribution in response to this survey.


Rasmussen, K., J. Calambokidis, and G.H. Steiger. 2001. Humpback whales and other marine mammals off Costa Rica and surrounding waters, 1996-2001. Report of the Oceanic Society 2001 field season in cooperation with Elderhostel volunteers. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 22pp Click here to view full report

Cascadia Research in collaboration with Oceanic Society has conducted a long-term research effort on humpback whales and other marine mammals off the Pacific coast of Costa Rica starting in 1996. In January and February 2001, we continued this research with Elderhostel volunteer support and completed our fifth season of effort. This report summarizes the research conducted on humpback whales and other marine mammals off southern Costa Rica as part of the Oceanic Society trips in 2001. The report summarizes the results from all six years of research in this region as well as initial efforts to examine humpback whale use of this areas by southern hemisphere whales. 

            Principal findings of the research over the years have included:

This information will be valuable in protecting managing marine mammals in Costa Rica. Tourism in Costa Rica has increased dramatically over the last 20 years, especially with visitors interested in terrestrial and marine wildlife. An expansion of resorts and tourist activities in Drake Bay has occurred over the five years of this research. With these increasing activities and interest in whales and marine mammals, it is important we learn more about the populations of many of these species to be better to protect them and educate people.


Calambokidis, J., T. Chandler, L. Schlender, K. Rasmussen, and G.H. Steiger. 2001. Research on humpback and blue whales off California, Oregon, and Washington in 2000.  Final report to Southwest Fisheries Science Center, La Jolla, CA.  Cascadia Research, 218½ W Fourth Ave., Olympia, WA  98501.  32pp Click here to view full report

Surveys were conducted in 2000 to continue long-term research studies of humpback and blue whales off California, Oregon, and Washington. Primary objectives of this work include examining the abundance and trends of these two species, movement and migration patterns, and reproduction and mortality rates. This research has also been conducted in association with studies on gray whales and incidental observations of other large whales. Although photographic identification was the primary method used, we also collected skin and fecal samples, made behavioral observations, measured sizes of whales, and deployed an underwater video/instrument package (Crittercam) on blue whales. Support for different aspects of this research in 2000 came from Southwest Fisheries Science Center, Olympic Coast National Marine Sanctuary, Office of Naval Research, Scripps Institute of Oceanography, National Marine Mammal Laboratory, and several individual contributors.

Photographic identification studies of humpback and blue whales were conducted off California, Oregon, and Washington April to December 2000. Dedicated surveys were conducted using Cascadia’s 5.3m RHIBs and on a few occasions other boats. Collaborating researchers and work from opportunistic platforms provided additional effort and identification photographs especially in Monterey Bay. Identification photographs were taken using standard procedures employed in past research (Calambokidis et al. 1990a, 1990b, 2000a).  Both sides of blue whales in the vicinity of the dorsal fin were photographed as well as the ventral surface of the flukes. For humpback whales, photographs were taken of the ventral surface of the flukes.

Dedicated and opportunistic effort results in 646 identifications of 254 unique humpback whales. Photographic identification of blue whales conducted in 2000 yielded 335 identifications of 168 unique individuals. Locations of sightings in 2000 were more clumped than in past years due to more limited support for field effort. More than half the humpback and blue whale identifications were made in the Monterey Bay area due to the steady concentrations of whales in this area and a high research effort in this area. The 2000 identifications provided updated abundance estimates for humpback whales of 715 (CV= 0.17), considerably lower than estimates in recent years and counter to the increasing trend seen since the early 1990s. The lower estimate appears to be at least partly an artifact of the lack of representative coverage in 2000. The unusually high proportion of the identifications coming from Monterey Bay in 2000 (66%) and in 1999 (50%) would likely cause heterogeneity in capture probabilities some which would bias the estimate downward. Mark-recapture estimates using the 2000 sample and the 1998 dataset which was not as geographically biased yielded an estimate of 856 (CV=0.12).

Several other components of the research proved successful in 2000. We attached (and recovered) a second Crittercam instrument to a blue whale in Monterey Bay in September in collaboration with National Geographic. The animal was feeding and yielded both images and the dive record of the animal's underwater behavior. Estimated sizes of humpback whales were determined using a laser range-finder and calibrated camera system. We also obtained biopsy samples of humpback and blue whales for determination of gender and genetic patterns.


Calambokidis, J., J. Francis, G. Marshall, D. Croll, M. McDonald, and T. Williams. 2001. Underwater behavior of blue whales using a suction-cup attached CRITTERCAM. Annual report to Office of Naval Research for Grant Number: N00014-00-1-0942. Click here to view full report

The overall long-term goal of the research is to examine the underwater behavior including the vocal behavior of blue whales. While increasing attention has been paid to the remote monitoring of blue whale behavior and vocalizations, relatively little is known about the behavior of individual animals. We monitored a variety of parameters including visual behavior, vocalizations, and dive patterns of blue whales in the context of known-gender identified animals. We attached an instrument package developed by National Geographic and termed Crittercam to blue whales that included underwater video, sound, depth and temperature by National Geographic. The project has the following objectives:

1.      Increase sample size of integrated visual, acoustic, dive and feeding behavior of blue whales

2.      Collect related data; history, sex, and size using photo-ID, skin sampling, and photogrametry

3.      Examine differences in behavior among three different habitats and seasons

4.      Bring together inter-disciplinary team to collaborate in the integration of the data components

5.      Additionally we seek test and improve methods for approaching and deploying instruments on blue whales that will be valuable for the deployment of other instrument packages being developed.

Deployments were successfully conducted in three region: Monterey Bay (northern California), off San Nicholas and San Miguel Islands in southern California, and in the Sea of Cortez, Mexico. To date, 17 deployments have been conducted on blue whales, with 8 of these successfully recovered instruments that stayed on the whale from 15 minutes to over 6 hours (including a single deployment completed prior to ONR funding). We have already learned a number of valuable things from these deployments, including:

1.      Developed the most effective approach methods for blue whales to deploy instruments; our success rate in attachment has gone from <10% of approaches where we contact the whale to 46%.

2.      Dramatically improved the performance of the Crittercams themselves including improvements in sound quality and more effective and redundant release mechanisms.

3.      Successfully obtained images of underwater behavior in conjunction with acoustical recordings and dive records of multiple animals in different regions and seasons. Underwater video has revealed diving behavior (Williams et al 2000) as well as feeding strategies.

4.      Preliminary examination of audio indicates most animals do not appear to be vocalizing. 


 

Calambokidis, J., M. Gosho, P. Gearin, J.D. Darling, W. Megill, M. Heath, D. Goley, and B. Gisborne. 2002. Gray whale photographic identification in 2001: Collaborative research in the Pacific Northwest. Report to the National Marine Mammal Laboratory, Seattle, WA. Cascadia Research, 218½ W Fourth Ave., Olympia, WA  98501.  19pp  Click here to view full report

This reports summarizes the field effort conducted by Cascadia Research in 2001 for gray whales and the results of comparison of the photographic identifications from this effort as well as that from field work conducted in 2001 by the National Marine Mammal Laboratory (NMML), West Coast Whale Research Foundation, Humboldt State University, Coastal Ecosystems Research Foundation, and the operator of the Juan de Fuca Express (a coastal ferry service). The field effort reported and these comparisons were conducted under contract to NMML.

 

Gray whale effort by Cascadia and the other collaborating organizations yielded a minimum of 938 identifications of 199 unique individual gray whales in 2001. This is more that has been identified in any past year. The majority of the identifications (630) were made along the West Coast trail of southern Vancouver Island. Among the 199 whales identified, 114 or 57% were whales known from previous years and already in the catalog maintained at Cascadia. Inter-year mark-recapture estimates using 2000 and 2001 yielded estimates of 322 (w/ California) and 246 (w/o California).


Calambokidis, J., T. Chandler, K. Rasmussen, G.H. Steiger, and L. Schlender. 2000. Humpback and blue whale photographic identification research off California, Oregon, and Washington in 1999. Final report to Southwest Fisheries Science Center, Olympic Coast National Marine Sanctuaries, and Channel Islands National Marine Sanctuary. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 39pp Click here to view full report

Surveys were conducted in 1999 to continue long-term research studies of humpback and blue whales off California, Oregon, and Washington. Primary objectives of this work have included examining the abundance of these two species, trends in population size, movement and migration patterns, and reproduction and mortality rates. In 1999 several other objectives were undertaken including deployment of an underwater video/instrument package on blue whales and testing a new method for measuring the sizes of whales. Support for this research in 1999 came from Southwest Fisheries Science Center, Olympic Coast National Marine Sanctuary, the Channel Islands National Marine Sanctuary, and several individual contributors.

Photographic identification studies of humpback and blue whales were conducted off California, Oregon, and Washington during dedicated surveys by Cascadia personnel on 64 days between 20 May and 3 November 1999. These were conducted using Cascadia’s 5.3m RHIBs and on a few occasions other boats. Collaborating researchers and work from opportunistic platforms provided additional effort and identification photographs especially in Monterey Bay. Identification photographs were taken using standard procedures employed in past research (Calambokidis et al. 1990a, 1990b, 1999a, 2000). Both the right and left sides of blue whales in the vicinity of the dorsal fin were photographed as well as the ventral surface of the flukes. For humpback whales, photographs were taken of the ventral surface of the flukes.

There were 449 sightings of 1,018 humpback whales approached in 1999 off California, Oregon, and Washington with an estimated 646 identifications made which yielded 348 unique individuals. Photographic identification of blue whales conducted in 1999 yielded 414 identifications of 178 unique individuals out of 361 sightings of 540 whales. Locations of sightings in 1999 were more clumped than in past years with most blue whale identifications made in the Santa Barbara Channel and more than half the humpback whale identifications coming from the Monterey Bay area.

Abundance estimates for humpback whales show that the population has continued to increase, the estimates using 1998 and 1999 samples is 1,024 (CV 0.097). These are the highest estimates we have obtained to date. Inexplicably, sightings of humpback whales calves remained low, likely indicating a bias in our observations. Long-range movement patterns of blue whales were examined in 1999 with the help of comparisons to identification photographs gathered by Cascadia in a 1999 cruise to the Costa Rican Dome and identification photographs from Mexico gathered by Diane Gendron (CICIMAR). These comparisons have revealed extensive movements of blue whales from California down to Mexico and the Costa Rica Dome in winter and spring.

Several other components of the research proved promising in 1999. We successfully attached a CRITTERCAM underwater camera (including a hydrophone and pressure and temperature sensor) to a blue whale in collaboration with National Geographic. This yielded excellent images of blue whale swimming behavior and contributed to an analysis of marine mammal diving strategies. We documented an anomalously pigmented white blue whale. Estimated sizes of humpback whales were determined using a laser range-finder and calibrated camera system. We also obtained biopsy samples of humpback and blue whales for determination of gender and genetic patterns.


Rasmussen, K., J. Calambokidis, and G.H. Steiger. 2000. Humpback whales and other marine mammals off Costa Rica, 1996-2000. Report on research during Oceanic Society Expeditions in 2000 in cooperation with Elderhostel volunteers. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 31pp Click here to view full report Cascadia Research in collaboration with Oceanic Society has conducted a long-term research effort on humpback whales and other marine mammals off the Pacific coast of Costa Rica starting in 1996. In January and February 2000, we continued this research with Elderhostel volunteer support and completed our fifth season of effort. This report summarizes the research conducted on humpback whales and other marine mammals off southern Costa Rica as part of the Oceanic Society trips in 2000. To make this report of broadest possible value, we also summarize the results from all five years of research in this region and consider the significance of the findings in relation to our research off the west coast of the U.S.. Cascadia Research, in conjunction with Oceanic Society Expeditions, and Elderhostel volunteer support, has conducted surveys based from Drake Bay, Costa Rica for two to four week periods in January and February between 1996 and 2000. Until these studies began in 1996, little information was available on humpback whales and other marine mammals that inhabit the waters off the west coast of Costa Rica.

Principal findings of the research have included:

The findings of the research off southern Costa Rica have gained a particular value in the context of our larger survey of Central American waters conducted with the schooner Russamee. That study revealed that large portions of the Central American coast are used as a wintering ground for humpback whales. This could mean this area collectively represents a wintering ground for far more humpback whales than we have suspected in the past. Detailed information in this broader region has only been gathered off southern Costa Rica, so this information provides an important insight into how whales use this larger area.


Calambokidis, J., S.J. Jeffries, P.S. Ross, and M. Ikonomou. 1999. Temporal trends in contaminants in Puget Sound harbor seals. Final Report to U.S. EPA and Puget Sound Water Quality Action Team. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 53pp Click here to view full report Harbor seals (Phoca vitulina) are the most abundant marine mammal species in Washington State and occur throughout the marine waters including Puget Sound. Extremely high concentrations of some chlorinated hydrocarbon contaminants, especially PCBs, were found in Puget Sound harbor seals in the 1970s and 1980s. One of the longest-term datasets on trends in contaminants in the Puget Sound region comes from harbor seals. Harbor seal pups from Puget Sound have been collected or biopsied for testing concentrations of PCBs and DDT compounds at 4-5 year intervals from 1972 to 1997 at several Puget Sound sites including Gertrude Island in southern Gertrude Island in southern Puget Sound and Smith Island in the Strait of Juan de Fuca. Samples from harbor seals are ideally suited for trend analyses because they are highly contaminated, represent an integration of concentrations in a broad selection of prey in a region, and, with the utilization of non-emaciated pups, provide limited inter-sample variability allowing sensitive detection of changes over time.

The most recent analyses were of both dead harbor seal neonates collected in 1996 and 1997 and biopsy samples of blubber from weaned harbor seal pups collected in 1993 and 1996 at Gertrude Island. We determined current levels of a broad range of chlorinated hydrocarbon contaminants in Puget Sound harbor seals including congener-specific concentrations of PCBs, DDTs and other pesticides, and the first analyses of polychlorinated dibenzo dioxins and furans (PCDDs and PCDFs). We tested both the most recent samples and re-tested some of the historical samples from 1984 and 1990 to provide more detailed data on historical contaminants.

Harbor seals have proven to be an excellent indicator of environmental contamination at the upper level of the food chain with clear spatial and temporal differences detected. While concentrations of PCBs and DDT have declined dramatically since the 1970s, concentrations have stabilized since the mid-1980s with only slight declines since then. Even though concentrations have declined, harbor seals are clearly still at risk, with the current concentrations of PCBs and the TEQ in pups within the range identified as causing immunotoxicity in seals. Most of the TEQ came from PCBs rather than PCDDs or PCDFs. We plan to continue monitoring trends in contaminants in harbor seals in Puget Sound at regular intervals and update trend data from other sites in Washington State.


Calambokidis, J., J. Quan, L. Schlender, M. Gosho, and P. Gearin. 1999. Gray whale photographic identification in 1998. Final Report to the National Marine Mammal Laboratory, Seattle, WA. Click here to view full report In 1998, Cascadia Research and the National Marine Mammal Laboratory conducted photographic identification surveys for gray whale found in the waters of Washington State and along the southern coastline of Vancouver Island. A larger regional effort was also conducted from California to Southeastern Alaska involving a number of other collaborators including researchers with Humpboldt State University, West Coast Whale Research Foundation, University of Victoria, University of British Columbia, Vancouver Aquarium, Department of Fisheries and Oceans, Coastal Ecosystem Research Foundation, and the operator of a coastal ferry service. This research updates previous research efforts, which have revealed that a large number of gray whales seen off Washington State and British Columbia exhibit localized site fidelity. The information provided by this research contributes to an ongoing study of abundance, movements, residence times, and return rate of gray whales that feed in the Washington State waters for extended periods. This report summarizes activities and preliminary results of gray whale research conducted in Washington State and southern Vancouver Island in 1998 by Cascadia and NMML. Results of the larger effort from California to Alaska will be summarized in a future report.

Between 2 March and 17 November 1998, Cascadia personnel conducted a total of 53 gray whale surveys in the waters of Washington State and off the southern coastline of Vancouver BC. The National Marine Mammal Laboratory (NMML) provided identification photographs from # surveys, conducted between 6 June and 18 November 1998. On 249 occasions, 74 different gray whales where successfully identified by Cascadia Research and NMML in 1998.

Fewer whales were present on the northern Washington and western Strait of Juan de Fuca than previous years and most of the identifications in this region were made late in the season (after 1 September). Of the 57 seen on the northern Washington coast and on the north and south side of the Strait of Juan de Fuca, 32 (56%) had been identified in past years, a lower proportion than previous years. Individual whales moved between S. Vancouver Island and the Strait of Juan de Fuca and Washington outer coast. At least six different whales were present (from 27 identifications) in northern Puget Sound; four of these were animals that have been seen regularly each spring in this area since the early 1990s. None of the four gray whales identified in southern Puget Sound had been seen previously, consistent with past findings that this area is not used by regular returning animals. 


Calambokidis, J., K. Rasmussen, and G.H. Steiger. 1999. Humpback whales and other marine mammals off Costa Rica, 1996-99. Report on research during Oceanic Society Expeditions in 1998 in cooperation with Elderhostel volunteers. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501.   Click here to view full report

Cascadia Research in collaboration with Oceanic Society has conducted a long-term research effort on humpback whales and other marine mammals off the Pacific coast of Costa Rica. In January and February 1999, we continued this research with Elderhostel volunteer support. For the first time in 1999, we also conducted a separate research cruise sponsored by National Geographic using the 50' schooner Russamee surveying humpback whales from Mexico to Costa Rica and a suspected blue whale breeding area 500 miles offshore of Central America.

This report summarizes the research conducted on humpback whales and other marine mammals off southern Costa Rica as part of the Oceanic Society trips in 1999. We also summarize the results from all four years of research in this region and consider the significance of the findings in relation to our research off the west coast of the U.S. and our broader survey of Central America. Cascadia Research, in conjunction with Oceanic Society Expeditions, and Elderhostel volunteer support, has conducted surveys based from Drake Bay, Costa Rica for two to four week periods in January and February between 1996 and 1999. Until these studies began in 1996, little information was available on humpback whales and other marine mammals that inhabit the waters off the west coast of Costa Rica.

Principal findings of the research have included:

This information will be valuable in protecting managing marine mammals in Costa Rica. Tourism in Costa Rica has increased dramatically over the last 20 years, especially with visitors interested in terrestrial and marine wildlife. An expansion of resorts and tourist activities in Drakes Bay has occurred over the four years of this research. With these increasing activities and interest in whales and marine mammals, it is important we learn more about the populations of many of these species to be better to protect them and educate people.

The findings of the research off southern Costa Rica have gained a particular value in the context of our larger survey of Central American waters conducted with the schooner Russamee. That study revealed that large portions of the Central American coast are used as a wintering ground for humpback whales. This could mean this area collectively represents a wintering ground for far more humpback whales than we have suspected in the past. Detailed information in this broader region has only been gathered off southern Costa Rica, so this information provides an important insight into how whales use this larger area.


Calambokidis, J., T. Chandler, K. Rasmussen, G.H. Steiger, and L. Schlender. 1999. Humpback and blue whale photographic identification research off California, Oregon, and Washington in 1998. Final report to Southwest Fisheries Science Center, Olympic Coast National Marine Sanctuaries, and University of California at Santa Cruz. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 35pp. Click here to view full report This report provides an update on the results of humpback and blue whale research based on the field work conducted in 1998. It summarizes the photo-identification results and examines distribution, abundance and population trends, and reproduction and mortality for humpback and blue whales. Surveys were conducted by Cascadia Research and a number of collaborators as a part of several studies. Cascadia personnel conducted 83 vessel days of survey effort between 4 May and 8 Dec 1998 covering most of the California coast and northern Washington. An addition, effort was conducted by collaborators who provided identification photographs to us.

Surveys were primarily conducted using two 5.3m rigid-hull inflatable boats (RHIBs). Individual identification photographs were obtained of humpback and blue whales using methods that have been employed in past research with these species. During survey effort by Cascadia personnel, 433 sightings of 1,027 humpback whales and 322 sightings of 437 blue whales were made off California and 23 sightings of 40 humpback whales were made off Washington. Combined with additional effort by a number of collaborating researchers these sightings resulted in 888 successful identifications of humpback whales representing 423 different individuals and 400 identifications of blue whales representing 228 individuals. This represents the largest sample of humpback whale identifications and one of the largest for blue whales we have obtained since our research began in 1986.

Humpback and blue whale identifications were obtained from a number of different areas and months and these indicated extensive movements among most regions. Humpback whales off northern Washington were an exception and animals from this region show a low matching rate with California and appear to be part of a separate feeding aggregation that begins north of about 47° 30’N.

New estimates of humpback whale abundance were obtained using several mark-recapture models. These provide a new estimate of 905 humpback whales for California-Washington. This feeding aggregation has shown a highly significant annual increase since 1988 averaging about 8% per year. The annual survival rate during this period has averaged 95%.


Calambokidis, J., L. Schlender, M. Gosho, and P. Gearin. 1998. Gray whale photographic identification in 1997. Final Report to the National Marine Mammal Laboratory, Seattle, WA. Photographic identification of gray whales in Washington State was conducted in 1997 by Cascadia Research and the National Marine Mammal Laboratory. This has been part of an ongoing research effort to study the abundance, movements, residence times, and return rate of gray whales that feed in Washington waters for extended periods. This report provides a brief summary of activities and in 1997 and preliminary results.

A total of 42 surveys were conducted by Cascadia personnel between 15 March and 10 August 1997 in Washington State. Identification photographs were also provided by the National Marine Mammal Laboratory from 47 surveys conducted from 31 May to 8 October 1997 in the western Strait of Juan de Fuca and the northern Washington coast. Individual gray whales were successfully identified on 178 occasions by Cascadia and NMML in 1997 (including one contributed photograph).

Thirty-seven different gray whales were identified primarily on the northern coast of Washington State and near the western entrance to the Strait of Juan de Fuca. Gray whales again spent little time in Puget Sound in 1997. Excluding seven suspected early-season migratory animals, 25 of 30 (83%) of the whales identified had been seen in past years. The total number of gray whales identified in the course of the study since 1984 now is 168. Individual gray whales were identified from one to 16 times each and extending over 100 days for two animals. Movements of animals in 1997 were commonly seen between the Washington outer coast and the Strait of Juan de Fuca and between these areas and southern British Columbia. Little interchange (even between years) has been seen between Puget Sound and other regions.


Calambokidis, J., K. Rasmussen, and G.H. Steiger. 1998. Humpback whales and other marine mammals off Costa Rica, 1996-98. Report on research during Oceanic Society Expeditions in 1998 in cooperation with Elderhostel volunteers. Cascadia Research, 218 1/2; W Fourth Ave., Olympia, WA 98501.     This report summarizes research conducted on humpback whales and other marine mammals off Costa Rica in 1998 and also compares these findings with those from the two previous years of this research. Until these studies began in 1996, little information was available on humpback whales and other marine mammals that inhabit the waters off the west coast of Costa Rica. Cascadia Research, in conjunction with Oceanic Society Expeditions, and Elderhostel volunteer support, has conducted surveys based from Drake Bay, Costa Rica for two to four week periods in January and February between 1996 and 1998.

    Principal findings of the research have included:

    This information will be valuable in protecting managing marine mammals in Costa Rica. Tourism in Costa Rica has increased dramatically over the last 20 years, especially with visitors interested in terrestrial and marine wildlife. An expansion of resorts and tourist activities in Drakes Bay has occurred over the three years of this research. With these increasing activities and interest in whales and marine mammals, it is important we learn more about the populations of many of these species to be better to protect them and educate people.

    In future years, it is important to complement the research at Drakes Bay with surveys covering an expanded geographic area. This would provide a better sampling of species that use other areas including more offshore waters, such as blue whales, and also provide a context for understating the relative importance of the Drakes Bay area compared to other coastal parts of Central America.


Calambokidis, J., T. Chandler, K. Rasmussen, G.H. Steiger, and L. Schlender. 1998. Humpback and blue whale photographic identification: Report of research in 1997. Final report to Southwest Fisheries Science Center, Olympic Coast National Marine Sanctuaries, University of California at Santa Cruz, and Cornell University. Cascadia Research, 218 1/2; W Fourth Ave., Olympia, WA 98501. 41pp.  Intensive research of humpback and blue whales off California using photographic identification has been conducted annually since 1986 with the primary objectives of examining population size and trends, reproductive rates, and movements of animals. The focus of the 1997 research was to gather data to achieve these overall objectives as well as to address other more specific objectives including studies in the Olympic Coast National Marine Sanctuary, and documentation of whales in the vicinity of two low-frequency sound sources (ATOC and LFA). This report summarizes the research effort and methods used in 1997 and the preliminary findings from this research including the number of individual whales identified, resightings, and movements of some of these animals.

Cascadia personnel conducted 150 vessel days of survey effort between 21 February and 5 November 1997 covering most of the California coast as well as northern Washington. An additional 87 days of survey effort was conducted by collaborators who provided identification photographs to us. During survey effort by Cascadia personnel, 284 sightings of 539 humpback whales and 207 sightings of 313 blue whales were made. Over 100 additional sightings of each species were made by collaborating researchers. These sightings resulted in 402 successful identifications of humpback whales representing 286 different individuals and 326 identifications of blue whales representing 182 individuals. Additional photographs were also taken of more than 50 fin whales primarily in the Southern California Bight, more than 30 "summer resident" gray whales in Washington State, more than 15 sperm whales primarily near Pioneer Seamount, and killer whales off Washington.

More than 80% of the humpback whales identified in 1997 had been seen in previous years. Only limited evidence of interchange was seen between humpback whales identified near the Washington/British Columbia border and those seen off California. The proportion of humpback whale calves seen in 1997 was higher than has been seen in most years and closer to that expected of a healthy increasing population. A higher proportion of calves was seen early in the season compared to late summer and fall. Abundance estimates of humpback whales for 1996-97 are now over 800 and are consistent with an increasing population.

The distribution of blue whales appeared to be different in 1997, with concentrations noted earlier in the season in some areas, such as the Santa Barbara Channel, than had been common in past years. Blue whales were much less common in the Southern California Bight in both inshore and offshore waters in the fall than had expected, resulting in low sighting rates in our fall surveys in these areas. Blue whale movements between a number of regions along the California coast were seen. The most dramatic finding, however, was the movement of one whale (ID# 1110) from off the Queen Charlotte Islands in northern British Columbia on 12 June 1997 (photographed by Randy Burke) to the Santa Barbara Channel on 10 July 1997. This represents a minimum distance of 1,347 nmi covered in a maximum time of 28 d. Both the transit between these locations as well as the direction of movement (south in early summer) were unexpected and suggest a connection between blue whales that summer off California and those that utilize more northern waters.


Calambokidis, J., G.H. Steiger, J.M. Straley, T.J. Quinn II, L.M. Herman, S. Cerchio, D.R. Salden, M. Yamaguchi, F. Sato, J. Urbán R., J. Jacobsen, O. von Ziegesar, K.C. Balcomb, C.M. Gabriele, M.E. Dahlheim, M. Higashi, S. Uchida, J.K.B. Ford, Y. Miyamura, P. Ladrón de Guevara P., S.A. Mizroch, L. Schlender and K. Rasmussen. 1997. Abundance and population structure of humpback whales in the North Pacific Basin. Report to Southwest Fisheries Science Center, National Marine Fisheries Service, La Jolla, California. 71pp. Click here to view full report     This project examined the abundance and population structure of humpback whales in the North Pacific and was the result of the collaboration of researchers from 16 independent studies. Locations sampled included three wintering regions (Mexico, Hawaii and Japan) and feeding areas from California to the Aleutian Islands. Photographs taken between 1991 to 1993 (later expanded to include 1990 for Mexico) were selected because samples throughout the entire North Pacific were the largest and the most complete during this period. Of the 6,414 photographs, 3,650 were selected based on photographic quality for the sample used in the comparison (including photographs from Mexico from 1990). Two matching teams made independent comparisons of the entire collection to identify resightings of the same whale. Several methods to evaluate their success in finding photographic matches revealed that 93-99% of matches were correctly found. A total of 2,712 (2,993 without inter-regional duplicates) different individual whales were determined to be present in the sample.

    The study provided new insights into the movements and population structure of humpback whales in the North Pacific. Although there was some interchange among the three wintering regions, it occurred only at a very low rate. While there was considerable mixing among the three subareas sampled off the Hawaiian Islands, interchange was more structured among the subareas in Mexico and Japan. In all three wintering regions, migrations from multiple feeding areas were documented. Whales identified at some feeding areas showed a clear preference for particular wintering regions (whales that fed off southeastern Alaska tended to migrate to Hawaii and whales that fed off California to Mexico) while at other feeding areas, animals tended to travel to multiple wintering areas. Whales identified off British Columbia, for example, showed a similar rate of interchange with all three wintering regions. Whales showed a strong site fidelity to specific feeding areas, although the near continuous distribution of whales along their feeding range and the limited sampling of most areas makes defining these feeding areas difficult.

  Abundance estimates were determined using several geographically stratified capture-recapture models. Two models (Darroch and Hilborn) that incorporate migration rates among wintering areas, yielded estimates of approximately 6,000 humpback whales (4,000 for Hawaii, 1,600 for Mexico, and 400 for Japan). Probable sources of downward bias to these estimates included a skewed sex ratio towards males sampled on the wintering areas and other sources of heterogeneity of capture probabilities such as from geographic sampling bias. Alternate Petersen capture-recapture estimates of the abundances of humpback whales in the wintering areas using whales initially captured on the feeding areas yielded slightly higher estimates for Hawaii (5,200) and dramatically higher estimates for Mexico (4,200). The disparity in the estimates for Mexico are likely the result of the uneven sampling among the three subareas and the stratification of movements among them. The true abundance for Mexico may be between these values which would be consistent with the estimates of 2,200-2,800 from other studies using a larger time period (Urban et al. 1994, In prep.). The best estimate of the humpback whale population in the North Pacific using data from this study was 6,010 (SE=474) based on the average of the estimates from the Darroch method. Adjustments for the effects of sex bias and use of the alternate estimate for Mexico suggests that true abundance could be as much as 2,000 whales higher (to a total of 8,000). Expansion of this methodology to a more representative sampling of the North Pacific would improve this estimate. Nevertheless, this study shows that the North Pacific humpback whale population is well above the rough estimates of 1,400 that were made at the end of whaling in the 1960s.


Calambokidis, J., J.L. Laake, and S.D. Osmek. 1997. Aerial surveys for marine mammals in Washington and British Columbia inside waters. Final report to the National Marine Mammal Laboratory, Seattle, WA 98115. Click here for full PDF of report.    Aerial line-transect surveys were conducted during August 1996 primarily to estimate harbor and Dall’s porpoise abundance in five regions, encompassing US and Canadian waters of the Strait of Juan de Fuca, San Juan/Gulf Islands, and Strait of Georgia. A total of 6,263 km (3,382 nmi) of on-transect effort were completed using a twin-engine high-wing aircraft flying at 90 knots and an altitude of 600 feet. Three observers searched for marine mammals through side bubble windows and a downward viewing port. Out of 1,505 groups sighted (3,340 animals) while on-effort, 1,074 were harbor seals, 311 were harbor porpoise, and 76 were Dall’s porpoise. We estimate abundance of harbor porpoise and Dall’s porpoise using line-transect methods. A re-analysis of aerial surveys conducted in 1991 was also completed to provide a comparable dataset using similar regional boundaries and analysis methods to look at temporal trends.

    Sighting rates of harbor porpoise differed significantly by region, year, Beaufort sea state, and cloud cover: rates were dramatically lower in the Strait of Georgia than all other regions, they were higher in 1996 than in 1991 for three regions that were surveyed in both years, and rates decreased with increasing Beaufort sea state and cloud cover. Sighting rates of Dall’s porpoise varied significantly by Beaufort sea state and cloud cover, but did not show any significant differences by year or region. The Strait of Georgia was excluded from these analysis because no Dall’s porpoise were sighted there. Abundance estimates were calculated using only sightings made in calm wind speeds (Beaufort sea state 2 or less) and clear skies (25% or less cloud cover). The abundance of harbor porpoise was estimated as 1,893 (CV=0.45) in the US Strait of Juan de Fuca, 1,239 (CV=0.41) in the Canadian Strait of Juan de Fuca, 1,616 (CV=0.38) in the US San Juan Islands, 745 (CV=0.53) in the Canadian Gulf Islands, and 911 (CV=0.58) in the Strait of Georgia. Total uncorrected Dall’s porpoise abundance was lower in 1996 (451, CV=0.23) than 1991 (1,095, CV=0.25) although this differences was not statistically significant. Our best estimate of Dall’s porpoise abundance for 1996 was 1,545 (CV=0.43) using a correction factor developed for harbor porpoise.

    Sighting data for the three most commonly sighted species, harbor seals (n=862), harbor porpoise (n=261), and Dall’s porpoise (n=68) were sufficient to determine their habitat preferences related to water depth, distance to shore and sighting rate differences for 352 km2 geographic cells. These species were found at most water depths, but sighting rates of harbor seals were significantly greater at shallower depths (two-way ANOVA, P=0.010) and Dall’s porpoise sighting rates were significantly higher in the deeper waters (P=0.001). Harbor porpoise distribution varied significantly by depth (P=0.013), with more animals occurring in deeper waters of the San Juan/Gulf Island regions. In the Strait of Juan de Fuca, no clear pattern in the depth distribution could be ascertained.


Calambokidis, J., T. Chandler, K. Rasmussen, G.H. Steiger, L. Schlender, D. Ellifrit, and J.L. Quan. 1997. Humpback and blue whale photographic identification: Report of research in 1996. Final report to Monterey Bay, Channel Islands, and Olympic Coast National Marine Sanctuaries, Southwest Fisheries Science Center, and University of California at Santa Cruz. Cascadia Research, 218 1/2; W Fourth Ave., Olympia, WA 98501. 40pp.    This report summarizes the research effort and methods used in 1996 and the preliminary findings from this research including the number of individual whales identified, resightings, and movements of some of these animals. While data obtained in 1996 will also be incorporated into the longer term objectives of the research effort, these overall findings will only be briefly reviewed here.

    Cascadia Research conducted photographic identification boat surveys for humpback and blue whales off the coast of Washington and California. In total there were 159 vessel days of survey effort including Cascadia vessels, NOAA ships (days when photographs were taken) and deployed inflatables, and collaborators (Table 1). For 128 of these surveys we had detailed information on effort and these involved 761 hours and covered about 6,709 nmi of search effort (not including the effort for opportunistic identifications ships during SWFSC cruises). In addition to effort from NOAA ships and Cascadia vessels identifications were also made from whale watch boats, other opportunistic platforms, and by scientific collaborators (primarily Nancy Black, Jeff Jacobsen, and Eric Martin). Major areas of emphasis included northern Washington, Monterey Bay to Bodega Bay, and the southern California Bight. Identifications were obtained as a part of Southwest Fisheries Science Center cruises off California, Oregon, and Washington, as well as off Pioneer Seamount near the location of the ATOC sound source.

    Humpback whales were identified on 617 occasions in 1996 representing 362 unique individuals. This is the second highest number of individuals we have identified in any year and brings the total number of individuals identified since 1986 to 908. A total of 157 humpback whales were seen more than once in 1996 representing 410 separate sightings. Although many of these were short term and short distance movements, there were also a number of longer intervals. The longest period over which an animal was sighted was over six months. A higher than expected proportion of humpback whales seen in 1996 had not been previously identified in our research. Research in 1996 and early 1997 has provided new information on the migratory connection of humpback whales feeding off California, Oregon, and Washington and those that winter off Costa Rica. Of 27 whales identified during the winter off Costa Rica through February 1997, 22 matched with whales identified off California (two of the five not matching were poor quality photos). This match rate (81%) is remarkably higher than other wintering to feeding areas, and suggests that whales wintering off Costa Rica are almost exclusively from California.

    Blue whales were identified on 296 occasions in 1996 representing 184 unique individuals. This total is slightly less than the number of identifications made in the previous two years but still provides a good sample for future mark-recapture calculations. The total number of individuals in the blue whale catalog is now 1,090. Of the 184 blue whales identified in 1996, exactly half (50%) had been identified in a previous year (part of Cascadia’s catalog). All identifications of blue whales were made south of the California/Oregon border, as has been the case in past years. A total of 62 individual blue whales were seen multiple times in 1996 (from 2 to 10 times). Documented movements included numerous short-term resightings in the same area as well as some long-distance movements.


Calambokidis, J. and J. Quan. 1997. Gray whales in Washington State: report on research in 1996. Final report to National Marine Mammal Laboratory, Seattle, Washington. 30pp.     This report summarizes research conducted by Cascadia Research in collaboration with the National Marine Mammal Laboratory during the 1996 field season. Cascadia Research has been conducting research on gray whales in Washington waters using photographic identification of individual animals since the mid-1980s (Calambokidis et al. 1994) with the goals of determining the number of whales using Washington waters, preferred areas for feeding, seasonality of use, and degree to which animals return year to year.

    Fifty boat surveys were conducted by biologists with Cascadia to observe gray whales between 15 March and 6 October 1996 totaling 243 hours of observation and 1,486 nmi of coverage. These included dedicated boats surveys conducted using a rigid-hulled inflatable and effort aboard whalewatch trips. The heaviest effort was in Grays Harbor, the western the Strait of Juan de Fuca, the northern Washington outer coast, and in the northern Puget Sound area. Data were also contributed by biologists at the National Marine Mammal Laboratory who provided identification photographs of gray whales made on an additional 13 days (between 13 June and 26 September) from surveys on the northern outer coast and the western Strait of Juan de Fuca. Gray whales were individually identified using photographs of the natural markings on the right and left sides. Comparisons of identified individuals were made to Cascadia’s catalog of over 100 gray whales seen in previous years off Washington as well as catalogs of identification photographs taken by collaborating researchers in British Columbia. A total of 112 sighting reports of gray whales were received by Cascadia Research and the Whale Museum in 1996.

    A total of 47 different gray whales were identified on 1996 in the study. A high proportion of the whales identified in three regions (northern Washington coast, Strait of Juan de Fuca, and southern Vancouver Island) were seen multiple times (73-79% by region) and had been identified in a previous year (64-82%). Gray whales identified near Grays Harbor early in the season were less likely to have been seen multiple times (52%) or a previous year (26%). Because most of these whales were identified in the migratory corridor during the migration (26-52%) when we would expect to be seeing migratory whales, this lower proportion of ‘resident’ whales was surprisingly high. Gray whales were frequently identified in multiple regions indicating movement patterns. Comparison of photographic catalogs with researchers working in British Columbia revealed that many of the whales that feed along the Washington coast through the summer range along the British Columbia coast to areas north of Vancouver Island.

  Conclusions of the research conducted through 1996 include:


Calambokidis, J. 1996. Gray whales in Washington State: Progress report on research in 1995. Final report to Washington Department of Fish and Wildlife, Olympia, Washington.     Cascadia Research has been studying gray whales in Washington waters since the mid-1980s. The goals of this overall research effort have been to characterize the different ways gray whales use Washington waters and to determine the number of individuals engaged in feeding and other critical activities. We have also sought to identify preferred areas for feeding, the seasonality of use, degree to which individual animals return year to year, and the number and reasons some whales die in Washington waters. This report summarizes research conducted on gray whales in Washington State during 1995.

  A number of methods were used to conduct the research including gathering sighting reports from the general public, conducting dedicated boat surveys to document and individually identify whales, cooperating with whale watch companies, examining dead whales, and assisting injured or entangled whales. A total of 28 boat surveys were conducted between 23 March and 24 October 1995. Observations were also occasionally made from land. Additional research effort was accomplished through a collaborative research effort placing students from the Evergreen State College aboard whale watch trips operated by the Mosquito Fleet, a company that operates gray whale watching trips. Photographs of distinctive markings on the sides of gray whales were used to identify and track individual animals. Sightings of gray whales from the public were solicited through use of toll-free hotlines operated by Cascadia Research and the Whale Museum. We examined gray whales that washed ashore dead and tried to assist animals that appeared sick or injured as a part of the Northwest Marine Mammal Stranding Network.

  Major findings or accomplishments of the research in 1995 included:


Calambokidis, J., G.H. Steiger, and K. Rasmussen. 1996. Humpback and blue whale photographic identification: Report of research in 1995. Final report to Monterey Bay, Channel Islands, and Olympic Coast National Marine Sanctuaries and Southwest Fisheries Science Center. Cascadia Research, 218&frac12; W Fourth Ave., Olympia, WA 98501. 37 pp.     This report summarizes research on humpback and blue whales along the west coast of the United States conducted by Cascadia Research in 1995. This research is part of a long term research effort designed to examine the distribution, population size, movements, migration patterns, and other aspects of the biology of these species. Research in 1995 was conducted with support of three National Marine Sanctuaries (Channel Islands, Monterey Bay, and Olympic Coast), Southwest Fisheries Science Center, and the University of California at Santa Cruz (as a part of the Marine Mammal Research Program) and was also designed to meet specific more regional objectives.

    Photographic identification of natural markings was used to recognize and track individual whales. We conducted small boat surveys off the coast of Washington and California. Cascadia personnel conducted 59 days of surveys aboard either Cascadia inflatables or from the NOAA ship McArthur with deployed inflatables (Table 1). These surveys involved about 500 hours of effort and covered about 4,380 nmi. Additional research was conducted from whale watch boats, other opportunistic platforms, and by scientific collaborators. Survey coverage was extensive with heaviest effort off northern Washington, Monterey Bay to Bodega Bay, and the southern California Bight.

    From 491 sightings of 1,039 humpback whales we identified 695 whales which revealed 352 different individuals (many whales were identified several times). This is the second highest number of identifications in a year since our research began and brings the total number of different humpback whales identified to 813. Primary areas where humpback whales were identified included the Santa Barbara Channel, Monterey Bay and waters north to off Half Moon Bay, the Gulf of the Farallones and Cordell Bank, and off the northern Washington coast. Frequent movement and interchange was seen among most of these regions with the exception of the northern Washington coast which appears to primarily be used by a separate group that feeds off northern Washington and British Columbia. A close connection including short transit times were documented between animals feeding off California and those wintering off Costa Rica and Panama (the furthest south a North Pacific humpback whale has been documented).

    From 321 sightings of 550 blue whales we identified 379 whales which revealed 239 different individuals . As with humpback whales, this is the second highest number of identifications in a year since research began and brings the total to over 900 different individuals identified off California (more than 1,000 including Baja California). The vast majority of sightings and identifications were made in the southern California Bight. Although blue whales were seen and identified in other areas, including Monterey Bay and the Gulf of the Farallones, fewer animals were seen and identified in these regions compared to previous years. Movements of individual blue whales during the season were documented, including transits from southern California to northern California and from southern California to southern Baja California.


Calambokidis, J. and G.H. Steiger. 1995. Population estimates of humpback and blue whales made through photo-identification from 1993 surveys off California. Report to Southwest Fisheries Science Center, National Marine Fisheries Service, La Jolla, California. 36pp.     This report summarizes the photographic identification research conducted in 1993 both from the SWFC (PODS) cruises and those conducted during coastal surveys and provides new abundance estimates and information on whale movements. A total of 128 blue whales and 247 humpback whales were individually identified during the coastal and SWFC survey effort in 1993. Abundances were estimated primarily using the Peterson cap-recapture model with samples consisting of identifications in different years or samples based on survey procedure (SWFC systematic surveys vs. Cascadia's coastal effort). The coefficients of variation for these estimates were calculated both using conventional methods as well as new more conservative jackknife procedure that treated subsamples as all the identifications in a region in a given time period.

    The best estimates of blue whale abundance were 2,038 (Jackknife CV=0.33, left side) and 1,997 (CV=0.42, right side) based on comparison of all photographs taken on the 1991 and 1993 SWFC cruises and the identifications from the coastal surveys for the same period. These estimates of about 2,000 blue whales are twice that obtained in previous capture-recapture analyses and are similar to the estimates obtained from line-transect estimates for the California coast.

    The best estimate of humpback whale abundance was 597 (CV=0.07) based on all samples obtained from surveys in 1992 and 1993. Abundance estimates using similar pairs of years going back to 1988, increased steadily from 498 to 597, or about 5% per year. These abundance estimates were in good agreement with those obtained using other capture-recapture methods (Jolly-Seber) as well as those obtained using line-transect methods.

    Additional data were obtained in 1993 on blue whale movements and distribution along the California coast. Three individual blue whales were photographed in both the 1991 and 1993 SWFC surveys, a surprisingly high number. Although evidence of preferences by some blue whales for coastal and others for offshore waters was again found, several blue whales moved from use of offshore to inshore waters both during a season or between seasons.

    Most humpback whales identified during the SWFC cruises were seen in coastal waters with only six identifications made in offshore waters outside the typical range of the coastal surveys (more than 50 nmi offshore). All but one of the six identifications made farther offshore were of whales that had been seen at other times in coastal waters. These findings confirm that most humpback whales use coastal waters and the few seen farther offshore are part of the same aggregation using coastal waters. Although a higher proportion of humpback whale calves were seen in 1993 (4.4 to 5.0%) compared to past years, this proportion remains low compared to studies of humpback whale populations in other areas.


Calambokidis, J. and R.W. Baird. 1994. Status of marine mammals in the Strait of Georgia, Puget Sound, and Juan de Fuca Strait and potential human impacts. p 282-303 In: Review of the marine environment and biota of Strait of Georgia, Puget Sound, and Juan de Fuca Strait. Proceedings of the BC/Washington Symposium on the Marine Environment, January 13 and 14, 1994. (R.C.H. Wilson, R.J. Beamish, F. Aitkens, and J. Bell, Ed.). Canadian Technical Report of Fisheries and Aquatic Sciences No. 1948. Click for full PDF of article     Nine species of marine mammals commonly occupy the trans-boundary waters of British Columbia and Washington (BC/WA). Animals of all species move across this international border. Of the four pinniped species common to these waters, harbour seals are the most numerous and the only one that breeds in these waters. Approximately 30,000 harbour seals occur in the trans-boundary area. Harbour seal populations have increased at 10-15% per year. The numbers of California sea lions and elephant seals have also been increasing steadily although neither breeds in BC/WA waters. Steller sea lions, a species that is declining through most of its range, also occur in this region. Of the five cetacean species common to the waters, harbour and Dall's porpoise are the most abundant and number in the several thousands. Harbour porpoise numbers in some areas have declined since the 1940s, though little data are available to assess current trends in populations of these two species. Killer whales are the best studied marine mammal species in the area, with most of the individuals in the populations that use these waters identified photographically. Over 20,000 gray whales migrate past the entrance to the Strait of Juan de Fuca and some individuals spend prolonged periods feeding in the spring and summer in BC/WA waters. A small number of minke whales also return annually to these waters to feed during the spring, summer, and fall.

    Marine mammal are vulnerable to human activities in the BC/WA trans-boundary waters. High concentrations of contaminants, especially chlorinated hydrocarbons and some metals, have been identified in these animals. Highest concentrations of contaminants have been found in harbour seals (from southern Puget Sound) and killer whales. Determination of the impacts of these contaminants on marine mammals in these waters has been inconclusive, though in other areas contaminant exposure has caused reproductive failure and immunosuppression. Marine mammals are killed incidental to commercial fishing operations, particularly harbour porpoise, Dall's porpoise, and harbour seals. Information to assess human impacts on most marine mammals and to adequately evaluate their current status is extremely limited.


Calambokidis, J., J.R. Evenson, G.H. Steiger, and S.J. Jeffries. 1994. Gray whales of Washington State: Natural history and photographic catalog. Report to Washington Department of Fish and Wildlife, Olympia, WA. Click here to view full report

Executive Summary:

    This report summarizes the research conducted by Cascadia Research on gray whales in Washington State up to 1994. This included boat surveys that yielded sighting information, photographic identification of individual animals, sighting reports from the public, and examination of stranded animals. The report also includes our photographic catalog of individual animals identified through 1993. A number of conclusions can be made from the data gathered to date: 1) Lower number of gray whales entered Puget Sound in 1992 than the previous two years based on sighting reports and number of individuals identified.

2) Gray whales were only seen in the Port Susan/Whidbey Island area, southwestern Strait of Juan de Fuca, and Grays Harbor.

3) In all three areas where gray whales were seen, most individuals were identified on more than one day indicating animals were staying for an extended period rather than migrating through the area.

4) Gray whales identified in the Port Susan/Whidbey Island area in 1992 were all individuals that had been seen in two or more years indicating a high return rate of animals to this area.

5) No gray whales died in Puget Sound in 1992 and none of three found dead along the outer coast had been identified in the area while alive.

6) The photographic identification of gray whales is a valuable inexpensive way to monitor the minimum number of whales in an area, their tenure in an area, and their return rate between years. The information gathered on individual whales would have been critical if any animals had died in Puget Sound in 1992, as had occurred in previous years.

7) Two different patterns of use are apparent for gray whales in Washington State. Gray whale use of the Port Susan/Whidbey Island area and the outer coast of Washington is characterized by a high rate of return year after year and the feeding on high prey densities. Though gray whales have been found dead in these areas, we have not seen a high mortality of identified individuals suggesting the animals dying were transient to the area. A second pattern is the occurrence of gray whales to the more southern portions of Puget Sound. Gray whale use of these areas is characterized by a high mortality of identified animals, no returns in multiple years, and the absence of a clear prey base.


Calambokidis, J., G.H. Steiger, and J.R. Evenson. 1993. Photographic identification and abundance estimates of humpback and blue whales off California in 1991-92. Report to Southwest Fisheries Center, National Marine Fisheries Service, La Jolla, California. 67pp.     This report summarizes a two year study completed under contract No. 52 ABNF100137 from Southwest Fisheries Center (SWFC). The primary purpose of the study was to develop abundance estimates using identified individual blue and humpback whales feeding off California and to examine their stock structure.

    Fifty-one dedicated vessel surveys were conducted between 16 July and 15 November 1991 and 73 surveys between 27 May and 16 November 1992 to obtain identification photographs of humpback and blue whales. Dedicated survey effort covered 368 hours and 2,714 nautical miles (nmi) in 1991 and 601 hours and 5,051 nmi in 1992. Primary vessels used were 16-18 ft inflatable boats with outboard engines.

    Additional identification photographs were obtained by collaborating researchers. Though some of this collaborative effort was opportunistic, 35 surveys in 1991 and 32 surveys in 1992 were conducted with the primary purpose of obtaining identification photographs for this study. SWFC also provided humpback and blue whale identification photographs from their CAMMS vessel surveys conducted along the California coast in 1991 (Hill and Barlow 1992). Photographs from these surveys valuable because they provided a representative sample of whales within 300 nmi of the California coast.

    Vessel effort was conducted primarily in areas where humpback and blue whales have been known to occur. Aerial sighting surveys, reports from SWFC and nature trip operators, reports from fishermen (solicited through posters requesting reports to a toll-free number), and boat scouting trips along more remote stretches of the coast were used to identify areas of whale occurrence. Vessel surveys were conducted at numerous locations along the California coast. Surveys crossed into southern Oregon on several occasions and one dedicated trip was conducted off northern Oregon.

    From sightings of just under 2,000 humpback whales in 1991 and 1992, we identified 482 different whales. More individuals were identified in 1992 (399) than in 1991 (264). A total of 338 individual blue whales were identified from sightings of just under 1,000 animals. Most of these identifications were made in 1992 when 287 individuals were identified. Only 77 individuals were identified in 1991.

    Humpback whales were seen and identified in six primary locations: 1) in the Santa Barbara Channel, 2) between Morro Bay and Pt. Sal off south-central California (1991 only), 3) around Monterey Bay (primarily 1992), 4) Cordell Bank/Gulf of the Farallones off central California, 5) around Fort Bragg (1992 only) and 6) the Pt. St. George area off northern California. Smaller numbers of humpback whales were also photographed in other regions. In 1991, blue whale were identified in coastal waters near Cordell Bank/Gulf of the Farallones and in offshore waters off southern California during SWFC vessel cruises. In 1992, blue whales were primarily identified in three regions: 1) Santa Barbara Channel, 2) Gulf of the Farallones/Cordell Bank area, and 3) Pt. Arena to Fort Bragg.

    Both southbound and northbound movement of both humpback and blue whales was documented along the California coast, primarily in 1992. Many of the humpback whale seen in June and July in the Santa Barbara Channel traveled north primarily to Monterey Bay. Of six humpback whales identified in May off Oregon, three were seen later in the Gulf of the Farallones. Similarly, blue whales were documented making frequent southbound and northbound movements.

    The humpback whales off California appear to be part of a feeding aggregation that ranges along the coast of California, Oregon, and Washington. Frequent interchange of humpback whales was found within this area, only limited interchange with southern British Columbia, and no interchange with areas farther north in British Columbia and in Alaska. Animals from the California coast primarily breed off Mexico with numerous matches between these areas. Four individuals, including one known female, traveled between California and breeding areas in Hawaii (as far west as Kauai). Some animals also traveled to breeding areas as far south as Costa Rica.

    Blue whales feeding along the California coast have been frequently identified along the west coast of Baja and in the Sea of Cortez, Mexico with over 78 matches between these regions. Movement to more distant regions is possible but could not be tested due to the small numbers of blue whale photographs available from other areas in the North Pacific. Based on their known occurrence throughout most of the year, however, it appears likely that the primary range for a substantial portion of the blue whales in the waters off Mexico and California. There was some degree of offshore/inshore segregation in blue whales, with animals seen during SWFC surveys in 1991 far offshore being infrequently seen during the coastal surveys.

    The best estimate of humpback whale abundance for the feeding aggregation using the waters of California, Oregon, and Washington, was from the Peterson mark-recapture estimate based on all samples from 1991 and 1992. This estimate was based on the largest samples, both of which covered broad geographic regions, and were the most recently taken. The estimate was 581 with a cv of 0.03.

    The best estimate of blue whale abundance came from the Peterson estimate comparing 1991 SWFC identifications to those obtained in the coastal surveys in Mexico and California from 1990 to 1992. This estimate was approximately 1,000 blue whales (904 with a cv of 0.41 for left sides and 1,112 with a cv of 0.34 for right sides) for the waters of Baja, Mexico and California. The small SWFC sample was used because it provided a representative sample of animals in inshore and offshore waters and therefore would not be biased by the offshore/inshore segregation.

    The number of humpback whale calves seen within the California-Oregon-Washington feeding aggregation appears low compared to other regions. The proportion of calves seen in humpback sightings along the California coast ranged between 2.3% and 4.0% of sightings and 2.6% to 4.7% of the humpbacks identified were females with calves.


Calambokidis, J., J.C. Cubbage, J.R. Evenson, S.D. Osmek, J.L. Laake, P.J. Gearin, B.J. Turnock, S.J. Jeffries, and R.F. Brown. 1993. Abundance estimates of harbor porpoise in Washington and Oregon waters. Report to the National Marine Mammal Laboratory, National Marine Fisheries Service, Seattle, Washington. 55pp. Click here to download full report (PDF)       Numerous surveys have been conducted in recent years to estimate harbor porpoise abundance for Washington and Oregon. The primary goal of this study was to evaluate the past data on harbor porpoise abundance and develop a revised abundance estimate the data from these data.

    To this end, we evaluated the suitability and comparability of past surveys. Four data sets from different surveys were selected for development of a revised abundance estimate:

 1) Vessel surveys dedicated to harbor porpoise estimation conducted in 1989 off the northern Washington coast (Calambokidis et al. In press),

2) Aerial surveys dedicated to harbor porpoise estimation conducted in 1989 off the coasts of Oregon and Washington (Turnock et al. In press),

3) Aerial surveys dedicated to harbor porpoise estimation conducted in 1990 off the coast of Washington (Calambokidis et al. 1991), and

4) Aerial surveys dedicated to harbor porpoise estimation conducted in 1991 off the coasts of Oregon and Washington and in Washington inland waters (Calambokidis et al. 1992).

    The methods used in the dedicated harbor porpoise aerial surveys conducted in 1990 and 1991 were identical and these data were pooled for analysis. Abundance estimates from the dedicated aerial surveys and vessel surveys conducted in 1989 were analyzed separately and then averaged (weighed by the inverse of variance) with the 1990-1991 dataset.

    Revised abundance estimates for the different data sets were usually similar to the original estimates. The only exception was the revised estimate of the 1989 dedicated aerial survey data which differed substantially from the original estimates. This was primarily the result of the different detection function we used in the analysis which excluded consideration of the area closest to the transect line. The area closest to the transect line had low sighting rates because of the absence of a center observer.

    Revised abundance estimates using all the survey data yielded estimates of 13,014 harbor porpoise off the coast of Oregon (including Heceta Bank), 10,074 off the southern Washington coast, 634 off the northern Washington coast, and 3,298 for the Strait of Juan de Fuca and San Juan Islands area. For the first time revised coefficients of variation (CV) for these estimates included the variance contributed by the correction factor for animals missed on the transect line. These CVs varied between 0.18 and 0.26 for the above estimates.

    All the surveys of Oregon and Washington coastal waters used in the revised abundance estimates covered waters out to a water depth of 50 fathoms (91 m). The revised abundance estimates are therefore only valid for the portion of the population inhabiting these waters. Surveys conducted by Ebasco Environmental for the Minerals Management Service surveyed waters much farther offshore for marine mammals and marine birds (Green et al. 1992). Though these surveys were not considered suitable for use in the abundance estimates (partly because of a much lower survey altitude) they did provide information on the proportion of harbor porpoise that occurred within and outside the study area covered by the dedicated surveys. A total of 24% of harbor porpoise sightings made during their systematic survey legs, extending from the coast to up to 100 nm offshore, were outside the area covered by the dedicated surveys used for the revised abundance estimate. This would result in a correction factor of 1.31 to adjust our abundance figures to cover the animals missed outside the study area.


Calambokidis, J., J.R. Evenson, J.C. Cubbage, S.D. Osmek, D. Rugh, and J.L. Laake, 1993. Calibration of sighting rates of harbor porpoise from aerial surveys. Report to the National Marine Mammal Laboratory, National Marine Fisheries Service, Seattle, Washington. 41pp.     Harbor porpoise abundance estimates have been made for Washington and Oregon using aerial and vessel surveys (Barlow 1988, Barlow et al. 1988, Calambokidis In Press, Calambokidis et al. 1991, 1992, Green et al. 1992 Turnock et al. In press). A major limitation of these estimates, however, has been that the fraction of animals missed on the survey line was not known. The primary objective of this study was to experimentally determine a correction factor for harbor porpoise missed during aerial surveys.

    Two methods were used to evaluate the correction factor for animals missed. The primary method for obtaining a correction factor was to measure the sighting success by aerial observers of specific harbor porpoise groups being tracked from land. Harbor porpoise groups in the study area were tracked from land prior to the aircraft passes. Secondarily, we gathered breath rate data on harbor porpoise groups to determine the proportion of time they are at the surface and likely to be seen by aerial observers. This was similar to the method used by Barlow et al. (1988) in devising a correction factor.

    The calibration experiment was conducted off the northwest side of Orcas Island in the San Juan Islands, Washington. Aerial surveys with a twin-engine aircraft were conducted in conjunction with land observations on 7 days between 3 August and 13 August 1992. A total of 547 transect lines were flown in 33 flight hours completing approximately 26 hours of transect surveys. Two teams, each consisting of 4-6 people made observations of harbor porpoise from land. Each team used an electronic theodolite interfaced with a computer data acquisition system. Radio contact between one of the aircraft personnel and the land teams was used to select aircraft transects that would include passing over a harbor porpoise group being tracked from land.

    To determine the proportion of harbor porpoise groups seen from the aircraft, several criteria were used to select the harbor porpoise groups that would be used for the calibration and to determine whether a group tracked from land was seen by the aerial observers. Harbor porpoise groups were included as a sample in the calibration only if: 1) they were seen from land within 4 minutes of the passage of the aircraft, and 2) were within 100 m of the aircraft transect line. A harbor porpoise group being tracked from land was considered seen by the aerial observers if: 1) the position of the porpoise determined from land and air was less than 300 m, and 2) the number of porpoise in the group determined from the air was not more than twice or less than half the size determined from land.

    Using the parameters described above, 28 of 92 (30.4%) harbor porpoise groups within 100 m of the transect line were seen by the aerial observers and 69.6% were missed. The point estimate for g(0) (the probability of sighting a group that was on the transect line) was 0.324 (SE=0.056). The sample size for this estimate was better than expected and provides a low enough variance that it will be able to be applied without greatly increasing the overall variance of abundance estimates. The correction factor for animals missed on the transect line was almost identical to that determined previously by Barlow et al. (1988) based on breath rate data of harbor porpoise.

    Seven different harbor porpoise groups whose surfacing were monitored spent an average of 36 sec (sd= 13.1) at or near the surface and 120 sec (sd=31.0) on longer dives of 30 sec or more. These values likely underestimate the time groups spend at the surface because some surfacings may have been missed. The proportion of harbor porpoise at the surface (potentially visible from the air) based on breath rates was slightly lower than the proportion seen in the calibration experiment. This may have been a result of our underestimating the time porpoise are at the surface (due to missing some surfacings). This also suggests that relatively few harbor porpoise on the transect line that were at the surface when the aircraft flew over were missed during the calibration experiment. The proportion of time we calculated harbor porpoise were at the surface from the breath rate data was similar to that reported by Barlow et al. (1988).


 

Calambokidis, J., J.B. Buchanan, G.H. Steiger, and J.R. Evenson. 1991. Toxic contaminants in Puget Sound wildlife. Report EPA910/9-91-023 to the U.S. EPA, Region 10, Seattle, Washington. 96pp.      Studies on birds and marine mammals from around the world indicate that environmental contaminants have adversely affected wildlife. This is especially well documented for stable chlorinated hydrocarbon compounds, such as DDT (and its major metabolite DDE) and polychlorinated biphenyls (PCBs), that occur at higher concentrations at higher trophic levels. However, the role of contaminants in the causation of a variety of biological disorders observed in Puget Sound wildlife is not well understood. This report summarizes the current understanding and implications of toxic contaminants in Puget Sound wildlife and provides recommendations for future research and monitoring. A primary objective of this report is to provide technical guidance on research and monitoring that, where possible, integrates a variety of approaches to identify contaminants and their impact on wildlife. This guidance id designed to support local, state, and federal agencies that may conduct research or monitoring of wildlife in Puget Sound. These agencies include the Puget Sound Water Quality Authority, Washington Department of Wildlife (WDW), U.S. Fish and Wildlife Service (FWS), and U.S. Environmental Protection Agency.

The scope of this report has been kept limited. Only bird and marine mammal species that feed in marine areas of Puget Sound are considered. The geographic scope considered in this report includes Puget Sound proper (Puget Sound basin south of Admiralty Island), the Strait of Juan de Fuca, the San Juan Islands, and the northern Washington inland bays (Padilla, Samish, Skagit, and Bellingham bays).

Research on contaminant concentrations in Puget Sound birds has focused on great blue herons, pigeon guillemots, glaucous-winged gulls, and waterfowl (Riley et al. 1983; Henny et al., in press; Kendall et al. 1990; Speich et al., in preparation). Surf scoters and western grebes were found to have accumulated higher concentrations of contaminants after wintering in Puget Sound, compared to concentrations in mid-fall, after the birds had just arrived (Henny et al., in press). Concentrations of PCBs and DDT were highest in gulls from Tacoma and Seattle, compared to concentrations reported for other regions around Puget Sound (Speich et al, in preparation).

Only limited research has been conducted on potential health problems in Puget Sound birds as a result of contaminant exposure. Significant eggshell thinning was found in great blue herons and glaucous-winged gulls in Puget Sound, apparently as a result of exposure to DDE (Calambokidis et al. 1985; Speich et al., in preparation). The impact on the great blue heron populations caused by the eggshell thinning was not determined. Glaucous-winged gulls from sites in Puget Sound exhibited anomalous liver weights compared to liver weights reported in other regions. The potential role of contaminants in this phenomenon has not been determined.

Principal research on contaminant concentrations and impacts on marine mammals in Puget Sound has focused on harbor seals. This species is a common resident and breeds in Puget Sound. Concentrations of PCBs found in Puget Sound harbor seals in the 1970s were among the highest concentrations recorded in the world (Arndt 1973; Calambokidis et al. 1978, 1984). However, these levels have declined significantly since that time (Calambokidis et al. 1988, 1991c). PCBs may have played a major role in reproductive problems that were reported in Puget Sound harbor seals in the 1970s (Newby 1973; Arndt 1973). Currently, populations of harbor seals are increasing in Puget Sound (Calambokidis et al. 1985, 1988).

Research on contaminant concentrations in other Puget Sound marine mammals has been more limited. In addition to PCBs, high concentrations of chlorinated hydrocarbon contaminants and mercury have been found in the limited number of killer whales examined from the Puget Sound Region (Calambokidis et al. 1984, 1990a). Killer whale pods that feed on other marine mammals had the highest concentrations of contaminants, consistent with their position at the top of the marine food chain. The role of contaminants in gray whale deaths in Puget Sound has not been determined, despite a great deal of speculation on this issue reported in the media. Concentrations of most contaminants, with the exception of aluminum, identified in stranded gray whales have generally been low (Malins et al. 1984; NMFS 1990).

Existing research is insufficient to adequately assess the impacts of contaminants on wildlife species in Puget Sound. Some of the data gaps involve the status and trends of wildlife populations and contaminant levels in wildlife that will require long-term monitoring. Other data gaps may be addressed through discreet research projects that address specific questions or hypotheses regarding contaminant impacts on wildlife. Research areas identified in this report as having the highest priority include:

In addition to these research areas, baseline information on exposure (and potential impacts) to contaminants is needed for some species found in Puget Sound including harbor porpoises, Dall’s porpoises, river otters, belted kingfishers, loons, and some waterfowl species. For species that are most commonly the subject of past contaminant research, data gaps on levels of heavy metals, coplanar PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and pentachlorophenol (PCP) should also be addressed.

Current monitoring plans for marine mammals under the Puget Sound Ambient Monitoring Program (PSAMP) include the examination of population trends, reproductive rates, mortality, and contaminant concentrations in harbor seals. Harbor seals are the best choice for initial monitoring of marine mammals because 1) they are resident and relatively sedentary in Puget Sound, 2) they are relatively easy to sample and have a population size adequate for sampling, 3) there is historical data on population size and contaminant concentrations, and 4) they are distributed at numerous sites around Puget Sound. Other species of marine mammals important for monitoring include killer hales, harbor porpoises, and gray whales.

Current and planned PSAMP monitoring of bird species provides valuable management and status information for a broad number of species. However, it does not provide information needed to examine contaminant-related problems in some of the species most likely affected by contaminants. In addition to the ongoing monitoring programs conducted by WDW and FWS, monitoring of populations and contaminants in several key resident species, including the great blue heron, belted kingfisher, and pigeon guillemot, is recommended. Shorebirds are not currently being monitored but represent an important group of species for ongoing study. Monitoring program recommendations focus on obtaining data on reproductive success and contaminant concentrations, as well as population status.
 


Calambokidis, J., G.H. Steiger, L.J. Lowenstine, and D.S. Becker. 1991. Chemical contamination of harbor seal pups in Puget Sound. Report EPA 910/9-91-032 to U.S. EPA, Region 10, Seattle, Washington. Click here for PDF of full report.     This report summarizes the results of chemical analyses of harbor seal pups found dead at two sites in Puget Sound. The first site was Gertrude Island in southern Puget Sound and the second Smith Island in northern Puget Sound. Blubber and liver tissues were examined both for organic and trace element contaminants. A wide range of tissues were also collected and analyzed for histop-pathology.

Primary conclusions from the this study are as follows:

1) Concentrations of PCBs in the blubber of seal pups were significantly higher for Gertrude Island compared to Smith Island. Concentrations of copper, lead, and silver in the liver of seal pups, however, were significantly higher at Smith Island compared to Gertrude Island.

2) Concentrations of PCBs and DDE in seal pups from Puget Sound have declined significantly since the start of testing in 1972.

3) PCB quantification using of standard matching is not well- suited to harbor seals because the PCB congener composition does not resemble any single commercial mixture. Standard matching can provide reasonably accurate estimates of total PCBs, however, if as many peaks as possible are used in the averaging and the standard or mix of standards is carefully selected approximate the congener composition of the sample.

4) Harbor seal pups, selected to meet specific criteria as in this study, provide an extremely useful tool in monitoring trends in contaminants concentrations in the upper levels of the food chain.
 


Calambokidis, J., G.H. Steiger, J.R. Evenson, and S.J. Jeffries. 1991. Censuses and disturbance of harbor seals at Woodard Bay and recommendations for protection. Final report to the Washington Department of Natural Resources, Olympia. 44pp. Click here to view full report     The Woodard Bay Natural Resource Conservation Area was purchased by the state of Washington. One of the important features of this site are the harbor seals that haul-out to rest and give birth to young on the log booms. This report summarizes research conducted by Cascadia Research and Washington Department of Wildlife on harbor seals at Woodard Bay (Henderson Inlet, Puget Sound) related to harbor seal abundance and disturbance and provides recommendations for management of the site.

    Personnel with Cascadia Research and the Marine Mammal Investigations of the Washington Department of Wildlife (WDW) have studied harbor seals during 300 visits (681 hours) to Woodard Bay by land or air between 11 August 1977 and 31 December 1990. Most of the effort was in 1984 (131.5 hours during 65 visits) and 1990 (217 hours during 67 visits). Disturbances of harbor seals at Woodard Bay were recorded beginning in 1984. During 1990, we conducted observations to determine the distance at which seals entered the water in response to approaching vessels.

    Harbor seals have used the log dump since at least the 1930s, though research on the seal numbers at this site began only in 1977. A number of factors were identified from the census data taken from 1977 to 1990 that influenced the number of seals at Woodard Bay in a statistically significant manner. These included: 1) time of day, 2) season, 3) year, 3) height of high tide, 4) rainfall, and 5) day of the week. These factors statistically accounted for over 50% of the variation in seal numbers observed throughout these historical censuses.

    Counts were highest in August to October, coinciding with the latter half of the pupping season and the molt. Harbor seal numbers have increased dramatically at Woodard Bay since regular monitoring began in 1977. The pace of this increase was most pronounced between 1977 and 1985, probably because 1) seal populations were increasing more rapidly and 2) an increased use of the log booms as a result of the slowing and eventual elimination of commercial activity at the site. Though seal numbers appeared to stabilize between 1985 and 1989, the censuses in 1990 have revealed that seal use of this site is still increasing.

    Pups are born at the Woodard Bay usually starting in early July, although viable pups were first seen in 1990 on 28 June. Births appeared to continue through early August when the maximum number of pups are seen. Births at Woodard Bay occurred on the log booms and especially on some of the areas that were covered with planks. The highest counts of pups made to date at Woodard Bay was 95 made on 7 August 1990. This high number indicates Woodard Bay is now approaching Gertrude Island as one of the most important pupping areas for harbor seals in Puget Sound.

    Disturbances of seals (human activities causing seals to enter the water) were seen on 45% of our observation periods in 1990 at a rate of 0.33 disturbances per observation hour. Disturbance rates were highest during summer months, weekend days, and weekday evenings, reflecting the factors that influence the number of people out on the water and around the site. Disturbance rates were higher in 1990 than any other previous year at the site. The disturbance rate at Woodard Bay in 1984 as well as 1990 was more than twice as high as at other sites we monitored in Washington State.

    The primary causes of disturbances of seals at Woodard Bay were people coming to the site in recreational motor boats, skiffs, and canoes or kayaks to observe the harbor seals. Most of the people who caused disturbances usually approached the seals without the apparent intention of disturbing or harassing the seals.

    Seals entered the water on the approach of vessel at distances up to 246 m, although the average was 56 m (n=44, s.d.=44). The distances that seals were disturbed varied significantly by vessel type; seals entered the water at a greater distance in response to kayaks and canoes compared to recreational motorboats and skiffs. Seals entered the water in response to people on foot at up to 256 m although, on many occasions, we were able to pass less than 100 m from seals while maintaining a low profile without causing disturbance.

    The impacts of disturbances on harbor seals have not been well studied though a number of possible effects have been identified by other researchers. These include: 1) change in behavior at site by altering haul-out times, 2) abandonment of preferred haul-out areas, 3) mother-pup separation during bond formation, 4) interruption of nursing, 5) increased stress during the molt, 6) potential stress during other seasons (e.g. mating), and 7) interruption of rest resulting in lower fitness and health.

    Due to a high rate of disturbance noted in July 1990, the following actions were taken in August 1990 to reduce disturbances: 1) signs were posted warning people not to disturb the seals, 2) newspaper articles were published describing the problem with disturbance at the site, 3) the National Marine Fisheries Service was provided with information on potential violators of the Marine Mammal Protection Act, and 4) buoys and lines were used to close off the entrances to the interior of the log booms. These actions were extremely successful and there was an immediate dramatic decrease in the rate of disturbances after they were put in effect.

    As part of this project for DNR, we have provided recommendations for long-term preservation of harbor seals at Woodard Bay. The most important recommendations are:

  1. The most critical period for harbor seals at the site is July and August when pupping is occurring at the site and September to October when animals are molting. Activities that might disturb harbor seals should be avoided during these periods. Activities that are disruptive to seals are best conducted in early morning hours and during rainy days.
  2. For the maximum seal numbers using Woodard Bay (possibly approaching 500 seals within the next few years), a minimum haul-out area of 1,250 m2 and 500 m of water access is required. The current log boom area provides a surplus of space for seals using the site at this time. Two types of structures, log booms and floats, represent the best choices for replacement habitat at Woodard Bay because both are used commonly by harbor seals. Given the current surplus of haul-out space at Woodard Bay, replacement of haul-out structures do not need to be implemented until space available reached 2,000 m2.
  3. Protecting seals from disturbance represents the major challenge for insuring that public access to the site does not threaten the use of the site by seals. Vessels (motorized and non-motorized) as well as people on foot should not be allowed to approach closer than 150 m from the seal haul-out area. A public viewing area closer than 150 m from the seals could be used if it was shielded from the seals.
  4. The harbor seals at Woodard Bay do provide a unique opportunity for educating the public and providing them with access to observe and understand marine mammals in a wild setting. An essential aspect of protecting marine mammals at Woodard Bay and other areas is to use this opportunity to allow people to see and learn about seals. Attempts to avoid disturbance of harbor seals do not need to prevent human access. Informing people on proper ways to observe marine mammals without causing disturbances can be an important educational value of their experience at the site.
  5. Future research and monitoring on seals should focus on the effectiveness of measures to prevent disturbance of seals as the human traffic at the site increases, future changes in seal numbers, seal food habits and their role in the ecosystem, and conflicts between seals with shellfish production at the site.


Calambokidis, J., G.H. Steiger, B.D. McLaughlin, and J.R. Evenson. 1990. Harbor seal haul-out habitat and the feasibility of shifting haul-out locations at Dosewallips State Park, Washington. Report to the Washington State Parks and Recreation Commission, Olympia, Washington. 70pp.       High fecal coliform concentrations that have been found at the Dosewallips River delta on the Hood Canal appear to originate from harbor seals that use the sloughs and marsh on the southern portion of the delta to haul out (Calambokidis et al. 1989, Calambokidis and McLaughlin 1988, DSHS 1988). In other areas in Puget Sound, harbor seals regularly haul out on human-made platforms, such as recreational floats and log booms (Calambokidis et al. 1978, 1985, Johnson and Jeffries 1977). Harbor seals used to haul-out on a log boom that existed at the north end of the Dosewallips River Delta through the mid 1970s. Because seal-related contamination is closely associated with haul-out locations, it may be possible to alter the affected areas by shifting the areas used by seals to haul out.

This study examines the feasibility of shifting the seal haul-out habitat at Dosewallips delta from the salt marsh areas used currently to human-made structures that would be located just off the delta. We summarize relevant findings about the biology of harbor seals at this location, harbor seal haul-out requirements, what steps would need to be taken to shift the location of haul-out, and limitations of trying to conduct such a project. This study was funded by the Washington State Parks and Recreation Commission.

Counts made on 49 days from December 1989 to August 1990 at Dosewallips Delta ranged from 11 to 390 harbor seals and averaged 140 (n=49, s.d.=85). A number of factors were identified that were statistically associated with the variations in the number of seals counted at the Dosewallips Delta. These included time of day, temperature, and tide height and time to high tide.

A major surprise in the results of this study were the significant decrease in seal numbers at the Dosewallips River Delta in recent years. This trend data should be viewed with caution, especially because it does not cover some critical seasons. There were not significant increases or decreases in seal numbers observed at Duckabush River Delta or Quilcene Bay.

At the Dosewallips River delta, harbor seals haul out along the three main southern sloughs and along or on logs along the river. We found significant seasonal and annual changes in the use of different portions of the Dosewallips River Delta.

A trial float placed at Dosewallips River delta on 16 May 1990 was not used by seals until 15 June 1990 and not regularly until late July. Females with pups occassionally hauled-out on the float in late August, towards the end of the pupping season. Exploratory behavior by seals in the water of the trial float was seen frequently.

The amount of haul-out space required per seal was similar among locations and habitats and averaged about 2 m2/seal. The area used by seals at human-made habitats tended to be slightly larger than natural habitats, though this difference was small. The mean shoreline distance per seal (the distance of shoreline or water access for a group of seals) was generally under 1 m/seal at natural habitats and greater than 1 m/seal at other human-made habitat.

Human-made haul-out areas appear to provide some advantages over natural habitats, especially in their accessibility at all tides and their rapid access to deep water. The height above water for human-made structures used by seals, including log booms, floats, and a fish net pen, ranged from 12 to 54 cm with log booms lowest in the water. The height above the water of many floats used by seals appear to prevent newborn seal pups from getting out on the float for the first 1-2 weeks.

An alternate haul-out structure able to accommodate the maximum seals seen using the current haul-out area (470) would need to be 1,175 m2 using 2.5 m2 per seal. Shoreline space would need to be at least 1 m per seal or about 500 m in total. This is less of a limiting factor since the haul-out area designs discussed below and human-made haul-out areas in general, easily meet this requirement.

Two human-made structures, log booms and floats, represent the best choices for alternate habitat at Dosewallips and a combination of both structures would provide the best alternative habitat for harbor seals. To allow segregation between groups we recommend use of multiple small structures as opposed to one or two large structures.

The ideal log-boom structure consists of three logs secured together by crosspieces with total width of 1.5 m. For the float design, the most suitable and compact structure would be a series of open-celled concrete floats. A fairly compact 12 x 17 m structure would be suitable for up to 60 harbor seals. A marked barrier around the structures would be necessary to keep boaters away from hauled seals and restrict them from using the structures for recreational purposes. The best location for an alternate haul-out site is along the steep slope marking the edge of the delta just north of the main river channel.

Seals may not readily adapt to new structures, as indicated by the delay in the use of the trial float. We propose actions that can be taken to encourage use of an alternate location. Additionally, options to discourage seal use of current areas include: 1) changes that elicit a behavioral avoidance by seals such as placement of a 'scarecrow' type object, 2) placement of physical barriers on marsh areas that restrict seal access to some or all haul-out areas, 3) placement of physical barriers at slough entrances to restrict access of seals but not smaller animals, and 4) disturbance of seals using haul-out areas. We recommend only the first two of these options be considered and only after seal use of alternate structures has begun, indicating these structures can meet seal haul-out requirements.

To evaluate the success of the project, we developed (in cooperation with personnel from the Department of Wildlife and Department of Health) a recommended monitoring program to be conducted if the relocation project is undertaken. The primary goals of the monitoring program would be to evaluate the success of the project to shift seal haul-out locations from marsh areas to new structures and to monitor trends in water quality for improvements as a result of the relocation activities.

A number of legal requirements exist for conducting this type of project. Discussion with personnel at the National Marine Fisheries Service, indicated that the information we have provided appear to be adequate to justify shifting haul-out locations as long as the method was non-lethal and alternate habitat were provided. A number of other permits are required, however, these all seem obtainable if public support of this project continues.

We do not expect significant impacts of seals at a new structure because they will be in deep, well-circulated water that is away from the intertidal zone where there would be more impacts. The large size of the proposed structures and their relative proximity to shore could pose an aesthetic impact, though this did not appear to be a concern expressed by residents of the area. Harbor seal predation on fish species would not likely be altered by the relatively minor shift in haul-out locations.

The experimental nature of this action makes it impossible to provide assurance of success even if all the procedures identified here are followed. The change in fecal coliform levels will probably be a slow process that may take years. The increased visibility of seals on a structure would make them susceptible to those who want to harm them. Additionally, the initial cost estimates for the artificial structures are high (over $100,000).

The project would have little chance for success should there be strong opposition from groups oriented towards protecting marine mammals or the local residents concerned about seal population increases. It is essential to maintain cooperation with these groups by including them in project evaluation.

Identified alternatives to the relocation option include no action (continue to prohibit shellfish harvesting in the state park), re-evaluation of the water quality standards, or elimination or reduction of the seal population. These alternatives are not feasible or would maintain the status quo.

We recommend that alternate structures be phased in gradually. This would allow evaluation of the success of the project prior to a full financial commitment and better identification of successful and unsuccessful approaches for shifting seal use. A series of steps are proposed for how to proceed on the project should State Parks decide to do so. The initial steps recommended before a final decision on implementation of the full project include:
 

This experiment was recommended by the technical advisory committee for this project and should be conducted over at least a one year period. The slough chosen for this experiment is the most northern of those regularly used by seals.
 


Calambokidis, J., G.H. Steiger, J.C. Cubbage, and K.C. Balcomb. 1989. Biology of blue whales in the Gulf of the Farallones and adjacent areas of California. Report to Gulf of the Farallones National Marine Sanctuary, San Francisco, Ca. 58pp. Click here for PDF of full report (2 MB)     Blue whale populations have been depleted as a result of commercial whaling conducted up to 1966. Blue whales were hunted in the Gulf of the Farallones from whaling stations operating out of San Francisco Bay. There has been little evidence to document the recovery of blue whales in the North Pacific since the end of whaling. Frequent sightings of blue whales in the Gulf of the Farallones, California since the early 1980s, and the results of this study, indicate the Gulf of the Farallones has become one of the major areas of concentration for blue whales on the west coast.

We studied blue whales in the Gulf of the Farallones (including coastal waters north to off Bodega head) from July to November of 1986 to 1988. Levels and type of survey effort were similar among years with a total of 1,457 hours of vessel surveys and 88 hours of aerial surveys conducted over the three-year period. Individual blue whales were identified from photographs using the pigmentation patterns on both sides of the whale near the dorsal fin. Blue whales were also identified outside the Gulf of the Farallones with the help of other researchers and naturalists who contributed photographs to our catalogue. The lengths of 39 blue whales were measured using aerial photogrammetry.

Increasing numbers of blue whales were seen in aerial and vessel surveys from 1986 to 1988. The distribution and timing of blue whale sightings from 1986 to 1988 were somewhat variable among years. Peak numbers were generally present in August to early October. The water depth of blue whale sightings varied significantly by year, with blue whales occurring in deepest water in 1987. Blue whales were significantly associated with concentrations of marine birds, primarily Cassin's Auklets and phalaropes.

There were significant differences in the lengths of blue whales measured in 1987 and 1988, average lengths were 20.5 (67 feet) and 21.8 meters (72 feet), respectively. This difference may reflect a segregation of animals by age class as has been documented in feeding areas of other baleen whales. The majority of the whales measured fell between the anticipated lengths of sexual and physical maturity. Few calves were seen during the research but this may have been as a result of calves having already been weaned prior to their arrival in the Gulf of the Farallones.

A total of 179 individual blue whales were photographically identified in the Gulf of the Farallones from 1986 to 1988. Most individuals were identified in 1988 (101) and 1987 (75). In both years more than 50% of these individuals were seen on only one day. In 1986, when 35 whales were identified, most whales were seen on more than one day. Fifteen percent of the identified whales were seen in more than one year and five individuals (3%) were seen in all three years.

Movement of blue whales between the Gulf of the Farallones and other locations to the north and south was documented through photographic matches of identified whales. In 1987 and 1988, five and three individuals, respectively, were seen in both Monterey Bay and the Gulf of the Farallones; all but one of these whales travelled from Monterey Bay in August to the Gulf of the Farallones in late August and September. A large number of blue whales were seen north of the Gulf of the Farallones near Point Arena in middle to late October 1988 and half of the animals identified (n=17) were seen in the Gulf of the Farallones in September or October.

Blue whales in the Gulf of the Farallones migrate from the west coast of Baja and the Sea of Cortez, Mexico. We identified blue whales from these areas using photographs provided by other researchers and whales catalogued by Mingan Island Cetacean Study. Nine blue whales seen in the Gulf of the Farallones have been matched to these areas. For example, three blue whales identified in March and April of 1988 off Baja, Mexico were seen in August or September 1988 in the Gulf of the Farallones or Monterey Bay.

Estimates of the number of blue whales occurring in the Gulf of the Farallones were possible from individual identification data and from aerial line-transect flights. A single line-transect flight conducted on 26 September 1988 provided area-dependent estimates of 160 and 250 animals in the study area, the highest numbers that we obtained. Mark-recapture estimates for 1988, despite the violation of a number of assumptions, yielded similar estimates of about 200 animals, depending on the time period and sides of the whale used in these calculations. Population estimates for 1986 and 1987 indicated lower numbers of blue whales than in 1988.

The high number of blue whales using the Gulf of the Farallones indicates it is an important area for this endangered species. The dramatic increase in numbers of blue whales that has occurred in the last seven years is extremely encouraging. If this increase continues the Gulf of the Farallones could become the single most important feeding area for the remnant blue whale population in the North Pacific.
 


Calambokidis, J., G.H. Steiger, J.C. Cubbage, K.C. Balcomb, and P. Bloedel. 1989. Biology of humpback whales in the Gulf of the Farallones, California. Report to Gulf of the Farallones National Marine Sanctuary, San Francisco, California. 93pp. Click here for PDF of full report (3 MB)      Under a research contract to the Gulf of the Farallones National Marine Sanctuary and the National Park Service, we studied the abundance, distribution, and behavior of humpback whales in central California from 1986 to 1988. The goal of the research was to gain information helpful to management and protection of humpback whales and other marine mammals present in the Gulf of the Farallones National Marine Sanctuary and the proposed sanctuary around Cordell Bank. In addition, other marine mammals were studied and research on blue whales was conducted concurrently to this study (see Calambokidis et al. 1989).

We conducted 1,457 hours of vessel surveys over the three year period primarily in August through October of each year. The purpose of the surveys was to photographically identify individual humpback whales and gather sighting information on marine mammals. We also flew over 88 hours of aerial surveys to examine the distribution of marine mammals, provide information on whale distribution to vessels, measure the length of whales through photogrammetry, and conduct line-transect estimates of abundance. Additionally, cooperating researchers and naturalists aboard nature trips in the region provided photographs of individual humpback whales and information on sightings.

Over 1,000 sightings of humpback whales were made during the vessel and aerial surveys in the study area. The sighting rates were highest in 1987 compared to 1986 and 1988. An influx of humpback whales occurred in August in all three years. Maximum numbers were seen from the middle of August to the middle of September in 1986 and 1987 and in September and October in 1988. The distribution of sightings in the study area varied both by season and by year. The areas around the Farallon Islands and to north of Fanny Shoal were some of the most consistent areas to find humpback whales. They were episodically abundant at other areas, including near Cordell Bank and north of Bodega Canyon (west of Bodega Bay), during some years and months. Humpback whales were significantly associated with water depths of 200 to 500 feet, though the depth varied significantly among years.

The changes in distribution we observed are likely the result of variations in the distribution and availability of prey, predominantly euphausiids and anchovies (Rice 1977). We examined raw data made available to us by D. Rice (pers. comm.) from humpback whales taken during commercial whaling in the Gulf of the Farallones from 1956 to 1965. In those catches there were dramatic annual and seasonal variation in the locations of capture, as well as annual variations in prey species.

Through fluke markings, we identified 225 different individual humpback whales from 1986 to 1988, with the most seen in 1987 when 141 were identified. Just over half the identified whales were seen in only one year (122), 65 were seen in two years, and 38 were seen across all three years. Three whales first identified by other researchers in 1981 were seen in our study, up to seven years later. On average, identified whales were seen more than five times each year. A "resident" subgroup of whales tended to be seen more often each year and across years. One of the humpback whales identified all three years was Humphrey, the whale that attracted public attention when it swam up the Sacramento River in 1985. During our study in 1986 and 1987, Humphrey was seen in consort with other humpback whales. However, in 1988 it was seen alone on three separate days in the shallow waters of Drakes Bay, Bodega Bay, and Bodega Harbor; all areas where we had not seen humpback whales previously.

Comparison of humpback whale photographs from the Gulf of the Farallones to those in other areas revealed movements of whales to other areas. Along the California coast, a majority of the humpback whales seen from Pt. Sur to Pt. Arena matched with whales in the Gulf of the Farallones, whereas a smaller proportion seen north and south of these points matched with the Farallones group (implying the existence of a central California feeding aggregation). The wintering grounds of central California humpback whales are preponderantly along the coast of Mexico and Central America. Twenty-three humpback whales seen in the Gulf of the Farallones (almost 10%) matched with Mexico and two matched with Costa Rica (provided by Richard Sears and the only two identified from this area). A few individuals (3) from the Farallones also occurred in Hawaii.

Few calves were seen during the study, though sightings increased over the three years. Calves were seen as 0.4%, 1.7%, and 5.3% of the whales sighted in 1986, 1987, and 1988, respectively. The proportion of identified cows with calves was low compared to other areas. The lengths of humpback whales measured from aerial surveys ranged from 10.5 to 13.6 m (n=24, mean=12.0, s.d.=0.76) and were generally smaller than lengths reported from whaling data.

Estimates of the abundance of humpback whales were calculated from line-transect aerial surveys and individual identification data. One aerial survey each year was flown using line-transect methods to provide a single-day abundance estimate. These estimates ranged from 60 humpback whales on 16 October 1986 to 109 on 25 September 1988. The number of individuals identified each year were higher than the line-transect estimates, probably reflecting individuals moving in and out of the study area. Within-year estimates based on mark-recapture yielded from 109 whales in 1986 to 211 in 1988 while between year estimates tended to be slightly higher, 226 for 1986 to 1987 and 253 for 1987 to 1988. However, we found violations of some assumptions of mark-recapture estimates based on the Gulf of the Farallones data.

Our estimates of population size are all lower than those reported for September 1982 by Dohl et al (1983). The population at that time was thought to be increasing based on the survey results from 1980 to 1982 and the reoccurrence of spring sightings of humpback whales near the Farallon Islands (Huber et al. 1980). Our data and that from other sources do not reveal an increase in humpback whale abundance. Instead there appears to be large annual variations in numbers, timing, and distribution of humpback whales in this area. Variations in timing and distribution also were apparent in the whaling data.

Sixteen other species of marine mammals were seen. The most frequently seen marine mammals included three pinniped species (harbor seals, California sea lion, and northern sea lions), three small cetaceans (Dall's porpoise, harbor porpoise, and Pacific white-sided dolphin), and two whales (minke whale and blue whale). Blue whale occurrence in the study area increased dramatically during the three years consistent with an increased abundance that began in the late 1970s (Calambokidis et al. 1989).
 


Calambokidis, J., G.H. Steiger, and B.D. McLaughlin. 1989. Bacterial contamination related to harbor seals in Puget Sound, Washington. Final report to Jefferson County and the Washington Department of Ecology, Olympia, Washington. 74pp. Click here for PDF of full report (40MB). High concentrations of fecal coliforms have been reported at several sites in northern Hood Canal where hundreds of harbor seals congregate to haul out and rest. A preliminary study concluded that harbor seals had the potential to be major sources of fecal coliform concentrations in these area. Even though the management options are limited for controlling contamination from a natural source, such as seals, information on their role in bacterial contamination is important because:
  1. Effective mitigation of human and domestic animal sources of contamination cannot be conducted without information on whether these sources are indeed responsible for the problem in an area.
  2. Public support for measures to reduce human and domestic animal sources is compromised if there is a perception that a major alternate source of contamination is not being examined.
  3. Information is needed to determine the areas where future problems for shellfish production are likely to occur.
  4. If fecal contamination in an area is predominantly of seal origin then the degree to which this contamination represents a health hazard needs to be determined.
In this study we evaluated harbor seal contributions to bacterial contamination and the health risk, if any, they pose. The objectives of the research were as follows:
  1. Determine the number of harbor seals occurring at haul-out areas in northern Hood Canal and evaluate the trend in population size.
  2. Determine fecal coliform concentrations in harbor seal feces and identify factors that may alter contamination.
  3. Examine fecal coliform contamination in water and shellfish at a site with high concentrations of seals and negligible other sources of contamination.
  4. Examine the bacterial contamination contributed by seals in a closed captive environment.
  5. Evaluate the evidence that harbor seals carry diseases transmissible to humans.
Our censuses indicated harbor seal numbers have significantly increased since 1984 at study sites in northern Hood Canal, once the effect of other variables including season and tide were taken into account. Two aerial survey counts indicated a minimum of 1,400 seals in Hood Canal, with up to 403 seals in Quilcene Bay.

Fecal coliform densities in harbor seal feces varied significantly by site, with dramatically lower concentrations in feces from captive seals. Significant differences also were found among the three sites where feces of wild seals were collected. Sampling variables may have accounted for some of these observed differences. Captive seal studies provided useful information on the dissolution of feces in the water column in a closed environment and demonstrated some of the limitations in estimating the contribution of fecal coliforms from seals in the environment. The large differences in fecal coliform densities in captive seals compared to those in the wild, however, limited the comparability to the natural ecosystem.
 

High levels of fecal coliforms were found in water and shellfish in Still Harbor, an embayment of McNeil Island that is the largest haul-out area for harbor seals in Puget Sound. Fecal coliform concentrations in both water and shellfish were highest at stations closest to the haul-out area. Bacteria also entered the bay from several small seasonal streams entering the harbor. The fecal coliform loading of these streams was far less than that calculated for seals, and the distribution of contamination was not consistent with these streams being the major source of fecal coliforms.



We conclude that the bacterial contamination at Dosewallips River Delta and at Still Harbor appears to be caused primarily by harbor seals. The role of seals in the bacterial contamination at Quilcene Bay is harder to determine because a number of other sources of contamination have been
identified and there is no evidence that contamination is highest at the seal haul-out areas. Continued increase of harbor seal populations in Puget Sound will only increase the potential for conflicts involving harbor seals and shellfish operations. The human health threat posed by seal fecal contamination cannot be determined with existing data.

Three avenues of future research are required to identify further the degree to which seal-related contamination poses a problem:

  1. Develop techniques to identify whether bacteria in marine water and shellfish are from seals or from humans or domestic animals.
  2. Examine the distribution of bacterial contamination in water and shellfish at Quilcene Bay and other sites with large numbers of seals to evaluate the source of contamiantion, as was done at Dosewallips and Still Harbor.
  3. Test seal wastes for the presence of pathogenic organisms to evaluate the human-health risks of this contamination.


Calambokidis, J. 1986. Chlorinated hydrocarbons in harbor porpoise from Washington, Oregon, and California: Regional differences in pollutant ratios. Final report for Contract No. 40ABNF5 3875 from Southwest Fisheries Center, La Jolla, California. 29pp.       Concentrations of PCB, DDE, HCB were examined in 51 blubber samples collected from 36 harbor porpoise collected along the coasts of Washington, Oregon, and California. The primary purpose of the study was to test for regional patterns in the concentration of contaminants and their ratios and to evaluate the feasibility of using contaminants to gain information about the degree of intermixing of harbor porpoise along the west coast of North America. Strong regional patterns were found in both the concentrations of DDE and the ratios of various contaminants. Contaminant ratios were far less variable then individual contaminant concentrations and were therefore more useful for examining regional patterns. The ratios of DDE/PCB and HCB/DDE showed the most dramatic differences by location with highly significant differences by state (ANOVA, p<0.001) and a strong correlation (p<0.001) between the ratio and latitude that the samples were collected. Within California samples from 3 subregions showed significant differences in contaminant ratios, though sample size was limited. The use of contaminant ratios to gain information on geographic interchange of harbor porpoise appears promising, especially in areas like California where the presence of pollutants in the marine environment varies widely by location.

    Significant patterns were also found in contaminant concentrations by year collected, animals length, and blubber thickness. Replicate samples of the blubber taken from different locations on the bodies of two harbor porpoise showed minimal variation. Only samples from the dorsal peduncle area of the porpoise deviated from values obtained from other parts of the body.


Calambokidis, J., S.M. Speich, J. Peard, G.H. Steiger, J.C. Cubbage, D.M. Fry, and L.J. Lowenstine. 1985. Biology of Puget Sound marine mammals and marine birds: Population health and evidence of pollution effects. NOAA Tech. Memo. NOS OMA 18, National Technical Information Service, Springfield, Virginia. 159pp.  The objective of this research was to determine whether detrimental effects possibly caused by toxic chemicals could be observed in Puget Sound marine mammals and marine birds. The study design was based on examination of a wide variety of indices of population and individual health and comparison of these indices from areas of suspected high contaminant levels (target areas) to those from areas of suspected low contaminant levels (reference areas) and to those reported by other researchers.

Recent research conducted in Puget Sound has revealed high levels of contaminants in fish, marine mammals, and marine birds. High contaminant levels in Puget Sound have been correlated to abnormalities and disorders in fish. Researchers have also reported correlations between contaminants and disorders in marine mammals and marine birds in other parts of the world.

Primary species considered here are harbor seal, Glaucous-winged Gull, Great Blue Heron, and Pigeon Guillemot; these species were chosen because they reside, feed, and breed in some of the most contaminated portions of Puget Sound. Three other mammal species (killer whale, harbor porpoise, and river otter) were chosen as secondary study species either because they seasonally occur in contaminated areas of Puget Sound or they were found through previous research to be experiencing problems that might be pollutant-related.

Target areas were chosen that were as close as possible to the heavily contaminated Elliott and Commencement Bays. Reference areas used for different species included sites north of Puget Sound, in the Hood Canal, and in Grays Harbor and Willapa Bay on the Washington outer coast.

Several biological parameters were examined to evaluate the evidence for pollutant-related problems. These parameters included population distribution, population trends, measures of reproductive success, mortality, causes of death, incidence of gross and histological pathology, and incidence of physical deformities or disorders seen in the population. To detect a broad range of possible effects, both general population health as well as incidence of individual disorders previously linked to contaminants were examined and measured.

Study methods varied by species. Censuses were made from the ground, boats, and from small aircraft and provided population figures for several species. Reproductive rates were determined from censuses and for birds, by observing marked nests. Mortality and the incidence of reproductive disorders were determined from breeding area searches and censuses made during the breeding season. Gross pathology was determined from necropsies of animals found dead and for some species from collected individuals. Samples for histopathology, microbiology, blood parameters, and eggshell thickness were collected from appropriate species and examined by specialists for comparison between locations. Tissues for contaminant analysis were collected and archived, but not analyzed.

We found a wide variety of disorders in some marine mammal and marine bird species. Some of these disorders followed patterns consistent with known patterns of contaminant concentrations in Puget Sound. Evidence for possible pollutant-related disorders is summarized in Table 1.

Overall, populations of the study species are doing very well, with the exception of the harbor porpoise and the killer whale; these two populations have declined in the Puget Sound area. For harbor porpoise the decline occurred prior to the 1970s and for killer whales the evidence of a decline is recent.

Harbor seal numbers are generally increasing in all our study areas, however, an unusually high incidence of premature births and neonatal mortality was found at some sites. These disorders are similar to those that have been linked to effects of contaminants in pinnipeds from other parts of the world. The high incidence of these disorders seen in Puget Sound seals, however, was found not at sites with suspected high contaminant levels but, rather unexpectedly, at study sites with suspected low contaminant levels. The most likely explanation for these problems is disease agents in these populations compounded by the possibility that these areas are nearing carrying capacity for seal numbers. A significantly higher incidence of pelage disorders and umbilical lesions seen in contaminated areas shows a pattern that suggests a relationship with contaminants.

Puget Sound marine bird populations do not appear to be declining or experiencing major reproductive problems. Two of three primary study species (Glaucous-winged Gull and Great Blue Heron), however, did show significant eggshell thinning compared to pre-1947 measurements. In addition, Pigeon Guillemots had lower overall eggshell thickness than those reported for pre-1947, but the difference was not statistically significant. These findings suggest a possible persistent detrimental effect of the pesticide DDT (and its primary metabolite, DDE) as has been reported for a wide variety of bird species in other areas. We also found evidence of highly variable liver weights in gulls that may have been associated with contaminants. No conclusive statements regarding the association between contaminants and eggshell thinning or liver weights can be made until chemical analyses of archived tissues are conducted.

Contaminant analysis of archived samples would greatly augment this study in several ways. This analysis is important in order to:

  1. verify our assumptions about contaminant exposure of different populations;
  2. provide a better comparison with findings in other areas;
  3. allow correlation tests between disorders found in specific animals and their contaminant burdens; and
  4. describe trends in recent contaminant exposure of marine mammals and marine birds.

Table 1. Summary of evidence for biological disorders possibly related to pollutants in Puget Sound marine mammals and marine birds. Except where noted data are based on biological observations in Puget Sound in 1984.


Calambokidis, J., J. Peard, G.H. Steiger, J.C. Cubbage, and R.L. DeLong. 1984. Chemical contaminants in Marine mammals from Washington State. NOAA Technical Memorandum NOS OMS 6, National Technical Information Service, Springfield, Virginia. 167pp. Click here for full PDF (large file)


    The objectives of this study were to report the results of recent analyses of environmental toxicants in Washington marine mammals and evaluate the evidence for pollutant-related effects in marine mammals. In the last eight years, samples of close to 100 marine mammals from Washington State have been analyzed for concentrations of the chlorinated hydrocarbons: polychlorinated biphenyls (PCBs) and 2,2-bis- (p-chlorophenyl)-1,1-dichloroethylene (DDE). These samples have consisted primarily of harbor seal tissues, but also include minke whale, killer whale, pygmy sperm whale, harbor porpoise, Dall's porpoise, an unknown species of sea lion, and river otter. Data from these analyses are summarized in this report. Tissues from an additional 17 harbor seals from Southern Puget Sound were analyzed for a broader range of synthetic chlorinated organics, metals and other trace elements, and polyaromatic hydrocarbons. These results are also reported.

PCB and DDE concentrations in harbor seals varied widely; the highest concentration of PCBs was 750 ppm (wet weight) found in the blubber of one harbor seal from Southern Puget Sound. PCB concentrations were substantially higher than DDE concentrations in all samples except in a couple of the cetacean samples. Concentrations of PCBs and DDE varied significantly by location. Seals from Southern Puget Sound contained the highest levels. Concentrations of PCBs and DDE also varied significantly by age, with adults showing higher concentrations than pups and subadults.

The concentration of PCBs and DDE are substantially higher in harbor seals than in the fish they eat. We found PCBs in the scat of seals and found evidence that some PCB components are metabolized by seals. However, an examination of the body burden of PCBs and DDE in seals indicates seals absorb most of the PCBs and DDE present in their diet and retain it in their blubber.

A number of other synthetic chlorinated organics were detected in harbor seals but in substantially lower concentrations than PCBs and DDE. Analyses for metals and trace elements in harbor seal liver and kidney revealed high concentrations of mercury (Hg) in some samples. High mercury concentrations occur frequently in marine mammals. We analyzed for polyaromatic hydrocarbons, but none were detected.

PCBs appear to be the primary pollutants of concern in Puget Sound marine mammals. PCBs have been implicated as the cause of reproductive problems in pinnipeds from the Baltic and Wadden Seas in European waters and the Channel Islands in Southern California. PCB concentrations in Southern Puget Sound harbor seals are among the highest found anywhere in the world and are in the same range as those implicated as causing biological disorders in other areas.

Reproductive disorders in harbor seals from Southern Puget Sound were reported in the early 1970s and pollutants may have been a contributing factor. A thorough study to determine the presence of possible contaminant-related disorders is needed.
 



 

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