111974

Despite their conservation status and central place in coastal and shelf ecosystems, Steller sea lions remain understudied in BC with important implications for Marine Protected Area planning and oil-spill response as well as understanding their ecological role vis-a-vis competition with other pinniped species, important prey for recovering Transient killer whales (TKW), assessment of potential competition with Resident killer whales (RKW) for fish prey species, or exploitation fish species whether ecologically, culturally, or commercially significant. Virtually nothing is known about how they utilize resources within the Scott Islands Protected Marine Area (SIPMA) which contains continental slope, shelf and sound ecosections, is a primary salmon migration corridor, is a key area for RKW, TKW and other SARA listed whale species (Grey, Fin), an array of listed seabird species and multiple other critical fish resources. To start to address these gaps we hope to generate broad ecological data on foraging of Steller sea lions within the PMA, basing our sampling efforts on Triangle Island. We will deploy satellite tags to define foraging movements and habitat use and generate seasonal estimates of diet through complementary approaches. During spring, 10 animals of mixed sex and age (adult/sub-adult) will be selected for monitoring at Triangle Island and immobilized using a Pneu-Dart remote delivery system by veterinarian staff of the Vancouver Aquarium with extensive experience in the chemical immobilization of otariids. Animals will be instrumented concurrently with 2 types of satellite tags: back-mounted tags will provide data on fine-scale foraging movements during the spring-summer period until they are shed during the annual fall moult, while flipper-mounted tags will provide multi-year information on haul-out behaviour. A full-core biopsy (skin-blubber-muscle) will be taken from instrument-deployed animals. Additional full-core biopsies will be obtained using a light-weight dart fired from a crossbow across different sex-/size-classes of SSL (up to 15). Scat samples (up to 50) will be collected from the beaches. A subsample of the soft matrix will be stored (5 ml vial) for DNA analysis. Samples will be run through a series of sieves to separate and retain the hard parts (bones, beaks) for size and species identification. We will return to Triangle Island in August for additional and similar diet sampling (biopsies and scats).