Subpolar Gyre and Temperature Drive Boreal Fish Abundance in Greenland Waters

Le résumé fourni par la source

As result of ocean warming, marine boreal species shift distribution poleward and increase in abundance at higher latitudes. A key to predict the impact of warming on these species is to disentangle the roles of anthropogenically induced climate change and natural variability. Scattered field observations in the first half of the 20th century suggested that boreal fish may coherently invade Greenland waters when temperatures rise, but this hypothesis has remained untested. Therefore, we studied how local temperature variability and the dynamics of the subpolar gyre, a large-scale driver of oceanic conditions in the North Atlantic, affect abundance of boreal fishes in a region that sharply defines their lower thermal boundary. We analysed information from demersal trawl surveys from 1981-2017 for species distributed from shallow shelf regions to depths of 1500 m collected at over 10,000 stations along ~ 3000 km of the coast of Greenland. Our results show that local temperature and variability of Labrador and Irminger Sea water in the subpolar gyre region drive interdecadal variability of boreal fish abundance in Greenland waters. Although temperature fluctuations were higher in shallow than deep regions, fish abundance changed as quickly in great depths as in shallow depths. This link between physics and biology provides an opportunity for prediction of future trends, which is of utility in Greenland, where fisheries constitute more than 90% of the national export value.

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