Temporal dynamics and environmental drivers of polar cod (Boreogadus saida) densities in the northeast Chukchi Sea

• Published in: Polar biology Vol. 46; no. 6; pp. 573 - 588
• Main Authors: Gonzalez, Silvana, Horne, John K., Danielson, Seth L., Lopez, Guzman, Segura, Angel M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2023; Springer; Springer Nature B.V
• Subjects: Automobile drivers; Biomedical and Life Sciences; Boreogadus saida; Cod; Ecology; Ecosystems; Fish; Fish populations; Fishes; Food chains; Food webs; Growth rate; High temperature; Larvae; Life Sciences; Marine ecosystems; Microbiology; Oceanographic data; Oceanography; Original Paper; Pelagic fish; Plant Sciences; Populations; Prey; Sea ice; Seafood industry; Secondary production; Spawning; Trophic levels; Water temperature; Whitefish; Zoology; Chukchi Sea; Arctic pelagic ecosystem; Acoustic backscatter; Polar cod; Chukchi Sea
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-023-03150-8

The Chukchi Sea pelagic ecosystem continues to undergo dramatic oceanographic changes associated with reductions in sea ice and increasing temperatures over the last decades. Impacts of these changes on polar cod ( Boreogadus saida ), an ice-associated pelagic fish that constitutes a key energetic link between lower and upper trophic levels, remain uncertain. Here, we use 4 years (2016–2019) of high-resolution acoustic and oceanographic data from the Chukchi Ecosystem Observatory to characterize temporal patterns in polar cod densities and identify its environmental drivers in years with contrasting sea ice and temperature conditions. Polar cod densities were 2–16 times greater with peaks occurring 14–60 days earlier in years with early sea ice retreat and higher water temperatures (2017 and 2019). The variance to mean relationship showed a decrease in variance for larger abundances in warmer years. Increased densities occurring earlier in the summer are attributed to a combination of earlier and increased transport of polar cod eggs and larvae from spawning areas, enhanced local primary and secondary production, and increased growth rates of fish due to higher temperatures. Earlier sea ice retreat and increases in temperature could temporarily benefit polar cod production in the NE Chukchi Sea but potential changes in prey quality, mismatch between polar cod and its prey, and increased competition with boreal fish species could have detrimental effects on polar cod populations with further warming. Such effects on polar cod populations could propagate through pelagic Arctic food webs impacting higher trophic levels and human communities.