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Knowledge of the biodiversity, biogeography and taxonomy of marine fishes in the Russian Arctic continues to expand

Fig. 1. The route of the R/V Professor Levanidov in the Siberian Arctic seas in 2019 (top left), trawl stations (triangles), including those where Lycodes spp. were caught (circles) in the Laptev (top right), Chukchi (bottom left), East Siberian (bottom center) and Kara (bottom right) seas.

Despite the growing interest in Arctic biota in recent decades, there are many gaps in our knowledge of the composition and distribution of species, including the Arctic ichthyofauna. One of the poorly studied groups is the Lycodes genus, which belongs to the widespread, numerous and species-rich Zoarcidae family in the Arctic. At least 34 species of this family have been recorded here, which is about 17% of the total species diversity of fish. Of these, about 70% are representatives of the Lycodes genus. These bottom dwellers of the shelf and continental slope play an important role in food chains, ensuring the transfer of organic matter and energy from bottom organisms to higher trophic levels (large predatory fish and marine mammals). Some Lycodes can reach a length of more than 50 cm and are considered suitable as food products, but their bycatch is currently not used, since they do not form dense clusters. The species composition and actual ranges of some Arctic lycodids still remain controversial due to insufficient study and often incorrect species identification.

Fig. 2. Different color variations of the seminude lycodes Lycodes seminudus (scale 1 cm).

The staff of the Zoological Institute, the Institute of Oceanology and the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences analyzed and summarized the materials on 12 species of lycodes collected during the expedition of the R/V Professor Levanidov in 2019 in four seas of the Siberian Arctic (Chukchi, East Siberian, Laptev and Kara). The morphological features and their variability, as well as the distribution of these species, are described and discussed. L.reticulatus was first discovered in the East Siberian Sea, L.pallidus in the Chukchi Sea, L. raridens in the Laptev Sea and L.rossi in the Chukchi and East Siberian Seas.

Fig. 3. The most morphologically variable in the Arctic is the pale lycodes Lycodes pallidus (scale 1 cm).

The obtained data significantly expand our knowledge of the modern ranges of Arctic ichthyofauna and may indicate the expansion of Pacific species into the Arctic. They also show that L. pallidus and L. polaris are probably the most numerous and widespread species in the three seas of the Siberian Arctic. Moreover, the first species is characterized by the widest range of morphological variability. The presented data are valuable for monitoring the biodiversity of Arctic ecosystems, which are subject to rapid transformation in the context of climate change and increasing anthropogenic pressure.

Published data of the article: Nazarkin M.V., Orlov A.M. 2024. Extending the knowledge of taxonomy, biodiversity, and biogeography of Arctic ichthyofauna: A case study of the most diverse genus Lycodes (Zoarcidae) // Zoologischer Anzeiger. V. 313. P. 355-365. https://doi.org/10.1016/j.jcz.2024.11.003