Overwinter habitat selection by Antarctic krill under varying sea-ice conditions: implications for top predators and fishery management

TitleOverwinter habitat selection by Antarctic krill under varying sea-ice conditions: implications for top predators and fishery management
Publication TypeJournal Article
Year of Publication2017
AuthorsReiss CS, Cossio A., Santora J.A, Dietrich K.S, Murray A., Mitchell B.G, Walsh J., Weiss E.L, Gimpel C., Jones CD, Watters G.M
JournalMarine Ecology Progress Series
Date Published2017/03
Type of ArticleArticle
ISBN Number0171-8630
Accession NumberWOS:000398911600001
KeywordsAntarctic krill; Bransfield strait; ccamlr; climate-change; Commission for the Conservation of Antarctic Marine Living Resources; crab-eater seals; environmental-change; euphausia-superba; Fishery interactions; fur seals; marine ecosystems; Ocean warming; scotia sea; sea ice; south shetland islands; Southern Ocean; vertical migration

Climate change will affect Antarctic krill Euphausia superba, krill-dependent predators, and fisheries in the Southern Ocean as areas typically covered by sea ice become ice-free in some winters. Research cruises conducted around the South Shetland Islands of the Antarctic Peninsula during winters with contrasting ice conditions provide the first acoustic estimates of krill biomass, habitat use, and association with top predators to examine potential interactions with the krill fishery. Krill abundance was very low in offshore waters during all winters. In Bransfield Strait, median krill abundance was an order of magnitude higher (8 krill m(-2)) compared to summer (0.25 krill m(-2)), and this pattern was ob served in all winters regardless of ice cover. Acoustic estimates of krill biomass were also an order of magnitude higher (similar to 5 500 000 metric tons [t] in 2014) than a 15 yr summer average (520 000 t). Looking at krill-dependent predators, during winter, crabeater seals Lobodon carcinophagus were concentrated in Brans-field Strait where ice provided habitat, while Antarctic fur seals Arctocephalus gazella were more broadly distributed. Krill overwinter in coastal basin environments independent of ice and primary production and in an area that is becoming more frequently ice-free. While long-term projections of climate change have focused on changing krill habitat and productivity declines, more immediate impacts of ongoing climate change include increased risks of negative fishery-krill-predator interactions, alteration of upper trophic level community structure, and changes in the pelagic ecology of this system. Development of management strategies to mitigate the increased risk to krill populations and their dependent predators over management timescales will be necessary to minimize the impacts of long-term climate change.

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