Pacific WildLife Foundation

……objective science for conservation…….

The Pacific WildLife Foundation is a non-profit coastal and marine research and education society  that inspires an appreciation for objective scientific research and conservation of the ocean. We conduct original research, develop novel education programs, and inspire an appreciation for conservation of the ocean. 

 
 
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Harbour Seal Phoca vitulina

 

The harbour seal is the most numerous and widespread marine mammal on the north Pacific Coast. It is found close to shore from Baja California to Japan. The subspecies of harbour seal on the north Pacific Coast of North America is the Pacific subspecies Phoca vitulina richardsi that ranges along the coast from Baja California to Japan (Baird 2001). Pelage colouration, dentition patterns, seasonal time of pupping and mitochondrial and microsatellite DNA evidence suggests that there might be several discrete populations on the Pacific Coast (reviewed by Baird 2001).

In recent years, the harbour seal has become a component of a flourishing whale watching industry but only a few decades ago, a bounty was in place to cull seals. Baird (2001) has reviewed the status of the harbour seal in Canada.

There is estimated to be at least 100,000 harbour seals in British Columbia (Olesiuk 1999). This estimate was made by counting seals at haul-outs and applying a correction factor to account for seals underwater during the census. The choice of correction factor introduces considerable error in the estimate but the conclusion that seals are far more numerous than in the 1970s is undeniable. Culling of seals occurred in Canada under a bounty system that ended in 1969. Since then, the population grew at about 12% annually and it is probably now at its pre-cull level (Olesiuk et al 1990).

Most harbour seals mate as monogamous pairs but some polygynous mating is also possible (Bigg 1981, Sullivan 1981, Riedman 1990). Mating occurs in the water making observations difficult. Pups are born earlier in the south than the north. In Washington and southern British Columbia, females give birth to a single pup in May or June, while in northern British Columbia and southeast Alaska pupping occurs in June and July. A pup about 80 cm long at birth will attain a length of 1.9 m as an adult and males are about 13% larger than females. The pups follow their mothers into the water soon after birth. They are weaned at about three weeks of age and females enter estrus a few weeks later. Females first breed between 3 and 6 years of age (most at 5 years; Bigg 1969a,b). Seals eat mostly fish but the diet includes many species such as herring, salmon, midshipman, ling cod among others and likely reflects local availability (Olesiuk 1993). Harbour seals are eaten often by ‘transient’ killer whales (Baird and Dill 1996, Watts 1993) and they are important predator of fish (Yurk and Trites 2000).

 

References

 

Baird, R. W. 2001. The status of the harbour seal Phoca vitulina in Canada. Canadian Field-Naturalist 115: 663-675.

 

Bigg,, M. A. 1969a. The harbour seal in British Columbia. Fisheries Research Board of Canada Bulletin 172, Ottawa.

 

Bigg, M. A. 1969b. Clines in the pupping season of the harbour seal, Phoca vitulina. Journal of Fisheries Resaerch Board of Canada 26: 449-455.

 

Olesiuk, P.F. 1993. Annual prey consumption by harbour seals (Phoca vitulina) in the Strait of Georgia, British Columbia. Fisheries Bulletin 91: 491-515.

 

Olesiuk, P. 1999. An assessment of the status of harbour seals (Phoca vitulina) in British Columbia. Canadian Stock Assessment Secretariat Research Document - 1999/33.

Available at http://www.dfo-mpo.gc.ca/csas/Csas/publications/ResDocs-DocRech/1999/1999_033_e.htm

 

Olesiuk, P. F., M. A. Bigg and G. M. Ellis. 1990. An assessment of the feeding habits of harbour seals (Phoca vitulina) in the Strait of Georgia, British Columbia, based on scat analysis. Canadian Technical Report of Fisheries and Aquatic Sciences 1730, Nanaimo, BC.

 

Riedmann, M. 1990. The pinnipeds: seals, sea Lions, and walruses. Univeristy of California Press, Berkeley, USA.

 

Sullivan, R. M. 1982. Agonistic behavior and dominance relationships in the harbor seal Phoca vitulina. Journal of Mammalogy 63: 554-569.

 

Yurk, H and A. W. Trites. 2000. Experimental attempts to reduce predation by harbor seals of out-migrating salmonids. Transactions of the American Fisheries Society 129:1360-1366.

  

 
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