Russian scientists are studying the “Atlanticification” and “pacification” of the northern seas
Global warming, which is most noticeable in the Arctic, is increasingly erasing the differences between its individual regions and the northern parts of the Atlantic and Pacific oceans. Head of the Laboratory of Oceanic Ichthyofauna of the Institute of Oceanology named after. Shirshov RAS, Doctor of Biological Sciences Alexey Orlov told MK which fish that previously did not live in the northern seas are increasingly being encountered by scientists there.
– With warming, fish expand their ranges and from the northern parts of the Atlantic and Pacific oceans begin to penetrate into the Arctic, as conditions there gradually become comparable in temperature and other parameters, – says Orlov. – In 2019, we carried out extensive expeditionary work across four Arctic seas, and recently also analyzed an extensive array of information, including open databases, from the mid-1970s to 2020. Based on all this, we presented new information on the abundance, biomass and size composition of six boreal fish species: black halibut, Pacific cod, Pacific pollock, blue catfish, beaked perch and benthos in the Kara Sea, Laptev Sea, East Siberian and Chukchi Seas .
– Pacific pollock, which was previously virtually unknown north of the Bering Strait. We discovered it in 2019 in large quantities (biomass about 1 million tons) in the Chukchi Sea and sporadically in the Laptev Sea. Moreover, we found adult individuals throughout the western part of the Chukchi Sea, which has never happened before. Pollock today – the only species of Pacific invaders that is already attracting the attention of industrialists. Starting in 2021, scientists recommend that they catch about 37 thousand tons of this fish. True, the climate and complex logistics in the Arctic still make fishing in this area risky: no one can yet know for sure whether a lot of pollock will come from the Bering Sea in a particular year or not.
Photos of fish caught in the Arctic and subarctic waters of Russia: black halibut (a), Pacific cod (b), pollock (c), spotted catfish (d), benthozema (e) and beaked perch (f). Photos by A.M. Orlova and I.I. Glebova.
– Perhaps, in second and third place in terms of occurrence, I would put black halibut and Pacific cod. Among the isolated representatives, such inhabitants of the temperate waters of the Atlantic and Pacific Ocean stand out as blue catfish, benthic lantern anchovy and beaked perch. Despite the fact that we only came across single specimens of perch in the Laptev Sea, Norwegian colleagues recently published data that they found beaked fish in the open Arctic.
Location of points of ship scientific observations in 1977-2020, used in the analysis of catches of boreal fish species in the waters of the Siberian Arctic. Photo: Progress in Oceanography.
– For example, juvenile pollock feeds in the water column, feeding on plankton, and as it gets older, it descends to the bottom horizons, where it finds larger prey – crustaceans (shrimps and amphipods), as well as juvenile fish.
Migration pattern of boreal fish species into the waters of the Siberian Arctic. Photo: Progress in Oceanography.
– Not always. TINRO (this is the Pacific branch of the All-Russian Institute of Fisheries and Oceanography) conducted a study and found that some pollock can linger in the Chukchi Sea during the winter period.