Arctic | Fishes and Fish Habitats
Forage-size fishes in the nearshore Arctic Presenter: Vanessa Von Biela , vvonbiela@usgs.gov, USGS Alaska Science Center Ashley Stanek , astanek@usgs.gov, USGS Alaska Science Center Brian Uher-Koch , buher-koch@usgs.gov, USGS Alaska Science Center Sarah Laske , slaske@usgs.gov, USGS Alaska Science Center Katrin Iken , kbiken@alaska.edu, University of Alaska - Fairbanks Kenneth Dunton , ken.dunton@utexas.edu, University of Texas at Austin
Of the three loon species breeding on Alaska’s Arctic coastal plain, red-throated loons ( Gavia stellata ) depend most on marine feeding and are the only loon species declining in abundance. Poor feeding and breeding success are implicated, necessitating more information about availability of forage-size fishes. To better understand food availability for red- throated loons, we sampled the Beaufort Sea nearshore to coastal marine transition zone where nesting loons forage for fish. Our sampling focused on two study areas adjacent to loon nesting lakes where we expected different marine fish communities: We expected higher diadromous fish abundance in the Sagavanirktok River Delta-Foggy Island Bay area because of the proximity to large rivers compared to the Canning River Delta-Flaxman Island region to the east. During initial work in July and August 2021–2022 surface trawls (n = 40) did not capture fish in depths of 2 to 20 m in either study area, suggesting that fish densities were very low and/or patchy. Fyke nets deployed continuously for up to 24 h along the shoreline at ~1 m depth had higher median catch per unit effort in Foggy Island Bay (249 fish/day, n=8) compared to Flaxman Island (53 fish/day, n=6). Among forage-size fish (<200 mm length) that are consumed by loons, median catch rates were similar between regions (81 fish/day) because fishes captured near Flaxman Island were more often forage-size. The most common forage-size fishes were Arctic smelt ( Osmerus mordax ), fourhorn sculpin ( Myoxocephalus quadricornis ), Arctic cisco ( C. autumnalis ), and broad whitefish ( C. nasus ) in Foggy Island Bay and Arctic cod (polar cod, Boreogadus saida ), fourhorn sculpin, saffron cod ( Eleginus gracilis ), and Arctic smelt near Flaxman Island. These preliminary results identify six species that could be important prey for nesting red-throated loons. Continuing effort will examine differences in prey quality, estimate loon diet from stable isotope and fatty acid analysis, and determine if loon nesting success differs between study areas.
Alaska Marine Science Symposium 2023 222
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