Cascadia stranding response and unusual sightings

As a part of the Northwest Marine Mammal Stranding Network, Cascadia is active in responding to strandings of cetaceans and pinnipeds. Primary long-term interests have included:

Cascadia collaborates with National Marine Fisheries Service and the Washington Department of Fish and Wildlife in stranding response and examination of stranded animals. Support for stranding response and research has come through the Prescott Marine Mammal Rescue and Assistance Grants Program.

Information on specific recent whale strandings in Washington

Other unusual cetacean sightings (not involving strandings)

Unusual sightings of Risso's dolphins in S Puget Sound (30 December 2011)

Record blue whales sighting off Washington (9 December 2011)

Pinniped stranding response

New publication documents harbor seal mortality at Smith Island (2 December2013)

 

Cascadia has responded to 182 pinniped strandings from 2003 to 2006 (Table 1) and assisted in another 52 examinations of pinnipeds conducted by WDFW (Table 2) in Washington State involving five species of pinnipeds. Both gross examinations of animals at necropsy combined with histological examination of tissues (conducted by Dr. Stephen Raverty of the Animal Health Center, BC) revealed a variety of causes of death of pinnipeds. Primary causes of death of pinnipeds included infectious agents, malnutrition/starvation, and accident/trauma.

 

Active searchers were conducted for stranded neonate harbor seals at several harbor seal haul out areas to collect tissues of non-starved neonates to monitor trends in contaminants in this indicator group. An exceptionally high rate of mortality of harbor seal neonates was found at this site in 2005 where in 5 visits in 2005, 110 dead pups were recovered from this site. Detailed examinations were conducted in collaboration with the WDFW and also the Animal Health Center in British Columbia but these did not reveal any consistent cause of death in the 2005 animals.

 

A variety of tissues have been submitted and are in the process of contaminant analysis. The focus will be analysis of non-starved harbor seal neonates that will provide data on long-term trends in contaminant concentrations going back to the early 1970s (Calambokidis et al. 1991, 1999, 2005). Longest trends will be available for PCBs and DDT compounds which were tested for in all analyses. Recent analyses completed has also included tests of metals and trace elements in liver tissues of harbor seal pups from Gertrude Islands in 2004 and 2006 and Smith Island in 2005.

 

Table 1. Pinniped stranding response by Cascadia Research, 2003-2006.

Species

2003

2004

2005

2006

Total

California Sea Lion

0

1

3

2

6

Elephant Seal

0

0

3

0

3

Harbor Seal

5

16

121

28

170

Northern Fur Seal

0

0

1

0

1

Steller Sea Lion

0

0

1

0

1

Unidentified Seal

0

0

1

0

1

Total

5

17

130

30

182

 

Table 2. Breakdown by species and year for necropsies or responses where WDFW was lead by Cascadia provided assistance, 2003-2006.

Species

2003

2004

2005

2006

Totals

California Sea Lion

0

5

0

2

7

Elephant Seal

0

0

1

1

2

Harbor Seal

0

9

11

14

34

Northern Fur Seal

0

0

0

2

2

Steller Sea Lion

0

1

1

5

7

Totals

0

15

13

24

52

 

Ship strikes of large whales

 

The following article was recently published summarizing evidence of ship strikes in large whales found dead in Washington State. Please click on title for PDF of full article:

Douglas, A.B., J. Calambokidis, S. Raverty, S.J. Jeffries, D.M. Lambourn, and S.A. Norman. 2008. Incidence of ship strikes of large whales in Washington state. Journal of the Marine Biological Association of the United Kingdom 88:1121-1132.

 

Below is the abstract of the publication in the Journal of the Marine Biological Association of the United Kingdom and presentation submitted to the 2007 Biennial Conference on the Biology of Marine Mammals in Cape Town, South Africa:

 

Ship strikes of large whales off Washington State, USA: an analysis using stranding records from 1980-2006

Douglas, Annie B.1; Calambokidis, John 1; Raverty, Stephen2; Jeffries, Steven J.3; Lambourn, Dyanna M.3; Norman, Stephanie A.4

(1) Cascadia Research Collective 218 ˝ W Fourth Ave., Olympia, WA 98506 USA

(2) Animal Health Center, British Columbia Ministry of Agriculture and Food, 1767 Angus Campbell Road, Abbotsford, BC V3G 2M3 Canada

(3) Washington Department of Fish and Wildlife, 7801 Phillips Road SW, Lakewood, WA, 98498, USA

(4) Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle, WA 98195 USA

Worldwide, fin whales have been recognized as the species most frequently affected by ship strikes, but as more research is undertaken, regional differences in species affected are becoming apparent. In the interest of evaluating ship-strikes off Washington State, an area where several species seasonally travel and feed within major shipping channels, we examined large whale stranding records from 1980-2006. Of 130 whale strandings, 19 (15%), representing seven species, had evidence of ship strikes. There was a significant increase in the number of ship-struck whales over this period, although the annual proportion of whales with evidence of ship strikes, compared to the total number of strandings, did not change significantly over time. Fin whales had the highest incidence of ship strikes (all seven strandings of this species), mostly consisting of immature animals with all but one occurring since 2002. Six gray whales suffered “possible antemortem ship strikes”; however, this represented only 6% of gray whale strandings since this species accounted for 80% of large whale strandings; indicating that the number of ship strikes likely reflects their seasonal abundance, rather than a high vulnerability to ship strikes. We recorded one of three stranded humpbacks as ship struck, despite concentrations of humpbacks feeding within shipping lanes. Other species documented with ship-strike injuries were blue (2/2), sei (1/1), sperm (1/3) and Baird’s beaked whale (1/1). We believe the dramatic difference in occurrence of ship-struck whales by species results from a combination of a species’ abundance, vulnerability to ship strikes, and the likelihood of a struck whale being caught on a ship’s bow and brought into waters where it may be discovered. Given the variability in species affected by ship strikes worldwide, awareness and solutions to this type of mortality will require consideration of differences in species vulnerability by region.