Ongoing borealization of Siberian Arctic marine ichthyofauna: Further evidence

The occurrence, abundance, biomass and size composition of six boreal fish species (walleye pollock Gadus chalcogrammus, Pacific cod G. macrocephalus, northern wolffish Anarhichas denticulatus, beaked redfish Sebastes mentella, Greenland halibut Reinhardtius hippoglossoides, glacier lanternfish Benthosema glaciale) in the Siberian and Pacific Arctic are presented based on the analysis of open databases (OBIS, GBIF and FishBase) and the results of scientific surveys of TINRO 1977–2020. In open databases, information on the records of these species is available mainly for the eastern Chukchi Sea and the Beaufort Sea and is practically absent for the seas of the Siberian Arctic, which is due to technical reasons. Data from long–term surveys of TINRO indicate the extension of the ranges of North Atlantic species eastward and North Pacific species westward indicating the ongoing borealization of the Siberian Arctic due to a changing climate. At the species level, it can lead to the overlap of the ranges of the “western” and “eastern” populations of Greenland halibut, as well as the ranges of Pacific and Greenland cods, which will make it possible to exchange genetic material between these populations/species and will contribute to the disappearance of genetic differences between them.