Pinniped stranding response

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

The following Cascadia publication documents harbor seal mortality at Smith Island:

CAUSES AND PATTERNS OF HARBOR SEAL (PHOCA VITULINA) PUP MORTALITY AT SMITH ISLAND, WASHINGTON, 2004–2010