Temperature, Sea Ice, Depth, and Traits Drive Fish Distributions in the Barents Sea

Abstract

Aim

Marine species are increasingly impacted by climate change, forcing them to adapt or redistribute to remain within their environmental niches. How the combined effects of environmental gradients and species traits influence the distribution of species with distinct biogeographic affinities remains poorly understood. The goal of this study is to identify the role of the environment, as mediated by species' traits, in shaping the fish communities of a high latitude marine environment with a clear biogeographic transition zone.

Location

The Barents Sea, a Subarctic ecosystem.

Methods

We fit a hierarchical model of species communities (HMSC) using 19 years (2004–2022) of bottom trawl survey data for 67 fish species in the Barents Sea. We incorporated environmental covariates (depth, temperature, salinity, mixed layer depth, and sea ice extent), species' traits (maximum body size, fecundity, and trophic level), and taxonomic relationships to quantify spatially structured community responses to environmental variation.

Results

Temperature, sea ice, and depth were the primary drivers of species' distributions across the Barents Sea. Arctic species were associated with cooler, deeper, and ice-covered waters, while boreal species occupied warmer, ice-free areas and exhibited more diverse responses to environmental gradients pointing towards a wider ecological niche. Clear spatial patterns for traits emerged across the polar front, in which smaller, less fecund, and lower trophic level species dominated the north, and larger, more fecund, higher trophic level species dominated the south.

Main Conclusions

These findings show that integrating environmental gradients, functional traits, and phylogenetic structure provides a robust framework for understanding fish biogeography and anticipating climate-driven community changes. Our findings are relevant for the continued effective management of this ecologically and economically significant fish community, especially as climate change progresses in this rapidly warming region.