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Harbor Seal Species Profile Encyclopedia of Puget Sound June 9, 2014

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Harbor Seal Species Profile Encyclopedia of Puget Sound June 9, 2014 (Photograph by G. E. Davis) Harbor seal species profile Encyclopedia of Puget Sound June 9, 2014 Jacqlynn C. Zier and Joseph K. Gaydos* SeaDoc Society / UC Davis’ Karen C. Drayer Wildlife Health Center Orcas Island Office 942 Deer Harbor Road, Eastsound, WA 98245 *Corresponding author [email protected] Table of Contents Introduction ............................................................................................................. 3 Distribution .............................................................................................................. 3 Global .............................................................................................................................................................................. 3 Local ................................................................................................................................................................................ 3 1 Populations .............................................................................................................. 4 Genetic diversity ........................................................................................................................................................ 4 Population size ........................................................................................................................................................... 5 Longevity and survival ........................................................................................................................................... 6 Physical Characteristics ........................................................................................ 6 Size and coloration .................................................................................................................................................. 6 Molting ............................................................................................................................................................................ 6 Whiskers ........................................................................................................................................................................ 7 Eyes ................................................................................................................................................................................. 7 Behavior ................................................................................................................... 9 Haul-out ......................................................................................................................................................................... 9 Haul-out frequency .................................................................................................................................................. 9 Haul-out site fidelity ............................................................................................................................................. 10 Hauling-out for predator avoidance ............................................................................................................ 11 Competition for haul-out space ..................................................................................................................... 12 Home Range ............................................................................................................................................................ 12 Adults ........................................................................................................................................................................... 12 Pups .............................................................................................................................................................................. 13 Diving ........................................................................................................................................................................... 13 Foraging ..................................................................................................................................................................... 14 Navigation .................................................................................................................................................................. 15 Diet ........................................................................................................................... 15 Impact on Depressed Fish Stocks ................................................................................................................ 18 Reproduction .......................................................................................................... 20 Mating .......................................................................................................................................................................... 20 Pupping ....................................................................................................................................................................... 20 Pup development .................................................................................................................................................. 23 Maternal effects on pup health ...................................................................................................................... 24 Pup effects on maternal health ..................................................................................................................... 24 Mother-pup interactions ..................................................................................................................................... 24 Fostering .................................................................................................................................................................... 24 Diving and Foraging ............................................................................................................................................ 25 Threats ..................................................................................................................... 26 Historic Culling ........................................................................................................................................................ 26 Predation .................................................................................................................................................................... 26 Disease ....................................................................................................................................................................... 28 Toxins .......................................................................................................................................................................... 34 Disturbance ............................................................................................................................................................... 35 Rehabilitation .......................................................................................................... 37 Literature Cited ....................................................................................................... 38 Acknowledgements ............................................................................................... 55 2 Introduction The harbor seal (Phoca vitulina) is the most commonly seen marine mammal in the Salish Sea and can be found throughout the region year round (Gaydos and Pearson, 2011). They have been intensively studied within the Salish Sea and this species profile provides an overview of what is known about them. Harbor seals are a widely distributed, small phocid species. Within Pinnipedia, the “feather-footed” order of seals, sea lions, and walruses, phocids are “true” or “earless” seals (Walker 1999). Harbor seals can be found along the temperate coastal regions of Europe, North America, and Asia. The subspecies P. v. richardii inhabits the majority of North America’s Pacific coastline, including the Salish Sea. Originally named Halicyon richardii in 1864 by John Edward Gray in honor of Captain George Henry Richards, leader of the 1861 to 1862 British survey expedition along Vancouver Island (Scheffer and Slipp 1944), the Latin name for the harbor seal was changed to P. richardii in 1902, P. v. richardsi in 1904, and finally P. v. richardii in 1942 (Scheffer 1958). In his comprehensive review of harbor seals, Bigg (1969a) used P. v. richardi. The Latin names Phoca vitulina richardsi (Huber et al., 2012 and 2010) and Phoca vitulina richardii (Carretta et al., 2013) are both currently used. Distribution Global Phoca vitulina is divided into five subspecies. In the North Pacific, P. v. stejnegeri and P. v. richardii are recognized, with P. v. stejnegeri being found in the western North Pacific and P. v. richardii in the eastern North Pacific. Phoca vitulina stejnegeri typically has a larger body size, a more massive skull, and darker pelage than the P. v. richardii. The three subspecies found along Atlantic Ocean coastlines are P. v. concolor in the western Atlantic, P. v. vitulina in the eastern Atlantic, and P. v. mellonae around the Ungava Peninsula of northeast Canada (Berta and Churchill, 2012). Phoca vitulina richardii is distributed from the eastern Aleutian and Pribilof Islands in Alaska south to Baja California,
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