Decline and northward shift in Arctic cod distribution associated with the changing climate around Greenland

Arctic cod (Boreogadus saida) is a key species in Arctic marine ecosystems, acting as a dominant mid-trophic link that transfers up to 75% of energy to higher trophic levels. It is central to cultural identity, food security and socioeconomic systems in circumpolar Arctic. Arctic regions are under rapid warming. This includes Greenland – an instructive high-latitude case, where climate change is expected to have “high to very high” impact on Arctic cod. This study combines trawl survey data and local and Indigenous knowledge to map Arctic cod distribution around Greenland. Findings reveal a substantial decline of this highly abundant species in both West and East Greenland since early 1990s, alongside a northward shift in distribution. This has happened surprisingly fast, during unfavorable habitat changes for early life stages, including rising sea surface temperatures, reduced sea-ice cover, and borealization of the prey field. Simultaneous northern shift in ringed seal catches adds to the suggestion that effects cascade all the way through the ecosystem from physics to human hunting activities. The study suggests that existing bottom trawl surveys, originally designed for larger fish, offer cost-effective monitoring of Arctic cod that serve as feasible early indicators of fundamental changes in Arctic marine ecosystems.