Under-ice distribution of polar cod Boreogadus saida in the central Arctic Ocean and their association with sea-ice habitat properties

• Published in: Polar Biology
• Main Authors: David, Carmen, Lange, Benjamin, Krumpen, Thomas, Schaafsma, F.L., van Franeker, J.A., Flores, H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Apherusa glacialis; GLM; Ice drift; Polar cod; Sea-ice properties; Under-ice habitats; amundsen basin; Arctic; Arctic Ocean; Boreogadus saida; Kara Sea; laptev; Laptev Sea; Nansen; Nansen Basin; Polar Biology; polar cod; Sea ice
• Online Access: https://research.wur.nl/en/publications/under-ice-distribution-of-polar-cod-boreogadus-saida-in-the-centr; https://doi.org/10.1007/s00300-015-1774-0

In the Arctic Ocean, sea-ice habitats are undergoing rapid environmental change. Polar cod (Boreogadus saida) is the most abundant fish known to reside under the pack-ice. The under-ice distribution, association with sea-ice habitat properties and origins of polar cod in the central Arctic Ocean, however, are largely unknown. During the RV Polarstern expedition ARK XXVII/3 in the Eurasian Basin in 2012, we used for the first time in Arctic waters a Surface and Under Ice Trawl with an integrated bio-environmental sensor array. Polar cod was ubiquitous throughout the Eurasian Basin with a median abundance of 5000 ind. km−2. The under-ice population consisted of young specimens with a total length between 52 and 140 mm, dominated by 1-year-old fish. Higher fish abundance was associated with thicker ice, higher ice coverage and lower surface salinity, or with higher densities of the ice-amphipod Apherusa glacialis. The fish were in good condition and well fed according to various indices. Back-tracking of the sea-ice indicated that sea-ice sampled in the Amundsen Basin originated from the Laptev Sea coast, while sea-ice sampled in the Nansen Basin originated from the Kara Sea. Assuming that fish were following the ice drift, this suggests that under-ice polar cod distribution in the Eurasian Basin is dependent on the coastal populations where the sea-ice originates. The omnipresence of polar cod in the Eurasian Basin, in a good body condition, suggests that the central Arctic under-ice habitats may constitute a favourable environment for this species survival, a potential vector of genetic exchange and a recruitment source for coastal populations around the Arctic Ocean.