Research on humpback and blue whales off California, Oregon, and Washington in 2000

Citation

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

Executive summary

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.  

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