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Pinnipeds Pinnipeds Sea Lions and Fur Seals Vs. Seals Walrus

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Pinnipeds Pinnipeds Sea Lions and Fur Seals Vs. Seals Walrus 3/1/2017 Pinnipeds Pinnipeds • Learning objectives • 35 species • Understand the differences between seals, sea lions and walrus • 16 species of eared seals (family otariidae, sea lions and fur seals) • Learn about the habitat and food requirements of these species • 18 species of seal (family phocidae, or true seals) • Examine the interaction between • 1 species of walrus (family odobenidae) • Walrus and a warming Arctic Ocean • Sea lions and salmon fishers • Seals and Puget Sound contaminants • In Salish Sea • Pacific harbor seal • Northern elephant seal (rare) • Sea lions: Stellar sea lion and California sea lion Sea lions and fur seals vs. Seals Walrus • Walrus (family Odobenidae) are large pinnipeds with tusks • Both male and female have tusks; can reach 1 meter in length! • Used for defense, movement, and anchoring onto ice • Arctic Ocean • Both Pacific and Atlantic sides • Benthic‐feeder –loves clams Sea lions and fur seals (Otariidae) Seals (Phocidae) 1 3/1/2017 Walrus population Primary habitat • Population size: ~200,000 • Walrus hunted during by whalers, 1700s –early 1900 • 15,000 to 20,000 walruses harvested annually in the mid 1800s • Today, a few thousand are taken each year and stocks have rebounded to near carrying capacity Garlich‐Miller et al. 2011 Sea ice Receding sea ice Declining Arctic sea ice Minimum sea ice extent No sea ice 2 3/1/2017 Land‐based foraging Satellite‐ Sea lion populations tagged • Walrus foraging from land walrus • California sea lion ~ 300,000 deplete local benthos • Steller sea lion ~ 100,000 in two • Walrus must undertake populations (western and eastern long migrations from land north Pacific) to find food • Both were listed as endangered • Walrus on land are more • Easter population may be delisted vulnerable to polar bear due to population growth attack USGS graphic Sea lion diet, Alaska Sea lions in the Columbia River • Sea lions eat a range of fish • Eat salmon when available • Conflict with people and with salmon recovery plans • Acoustic deterrents don’t work • Sea lion exclusion devices work better Cod lance tooth ‐ • Still eating salmon below Bonneville dam Pollock Sculpin Salmon Herring flounder Mackerel Sand Pacific Cephalopod Arrow 3 3/1/2017 Estimated salmon consumption by sea lions Timing of sea lion predation on salmon Harbor seals Harbor seals in Bellingham Bay • Phoca vitulina • Harbor seals hang out in • Several sub‐species Bellingham Bay! • World‐wide population ~ 500,000 • Haul‐out sites are near the old • In PNW, about 500,000 killed for GP plant and off Boulevard Park pelts or bounty • WA State sponsored seal hunts until 1960 • In 1972, hunts ceased due to Marine Mammal Protection Act • Today, perhaps 50,000 in Salish Sea Farer and Acevedo‐Gutierrez (2010) 4 3/1/2017 Adult seals and seal pups can be seen in late Timing of seal presence in Bellingham Bay summer • Seals arrive with salmon • Appearance of pups in Bellingham is consistent with seal pupping season in the • Seal abundance does not peak Salish Sea at the peak of salmon run, but perhaps this is because seals were counted infrequently and at the same time of day? Farer and Acevedo‐Gutierrez (2010) Farer and Acevedo‐Gutierrez (2010) Harbor seal diet Harbor seal diet varies with season and location • Data from scat samples • Eat primarily herring in winter and spring • Eat mostly adult salmon in summer and fall Lance et al. 2012 Ward et al. 2011 5 3/1/2017 Seal movements in the Salish Sea Short‐distance movers • It had been thought that harbor seals remain within ~ 30 km of their haul‐out sites so that foraging impact was limit in area • Satellite tagged seals made some long treks, up to 400 km! • Males move farther • Females stay closer to home Problems with staying local Long‐distance • Can deplete local fish populations movers • In Puget Sound, harbor seals pick up contaminants from the fish they eat (Ross et al. 2013) 6 3/1/2017 Harbor seal persistent organic contaminants Harbor seal persistent organic contaminants polybrominated diphenylethers Harbor seal health index (1.3 mg/kg: Immunotoxicity and endocrine disruption) PCBs banned in US in 1976 In Canada in 1977 PBDE (flame retardant): Production of certain types polychlorinated naphthalenes ceased in 2004 Drops may also reflect a temporary increase in migratory herring in late 2000s BC SJF Puget Sound BC SJF Puget Sound Summary • Pinnipeds are comprised of eared seals, true seals and walrus • Walrus use ice floes to efficiently traverse the continental shelf and access new feeding grounds • Loss of sea ice restricts walrus to land for most of summer and fall • Sea lions have a varied diet including many species of fish and even octopus • Sea lions take advantage of seasonal fish availability, especially at dams • Harbor seals are the most abundant pinnipeds in the Salish Sea • They too eat a variety of fish but have high contaminant loads 7.
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