Offshore demersal fish community structure and habitat associations in Amundsen Gulf, Canadian Arctic

Abstract

Marine fishes occupy a range of trophic positions, all of which play integral roles in energy pathways within and amongst habitats. Understanding marine fish community structure and habitat associations is prerequisite to understanding ecosystem structure and function in the western Canadian Arctic, and the lack of regional-scale information impedes effective regulation of emerging industrial activities and climate adaptation strategies. Our study documented 46 demersal fish species from 29 genera, recording eight new species occurrences for Amundsen Gulf. The demersal fish community of Amundsen Gulf is largely structured by the depth-mediated water masses of the region where they interface with seafloor habitats. The fish assemblages appeared stable over the seven-year span of the study, while interannual fluctuations in abundance reflected species-level variability. Species richness was higher in Amundsen Gulf relative to the adjacent Canadian Beaufort Shelf and slope, but indexes for evenness and species dominance in Amundsen Gulf were skewed by the pervasiveness of Boreogadus saida. The average abundance of B. saida was 4.7 times higher at stations where fishing occurred within Atlantic waters relative to Pacific waters, with peak average abundance documented in Minto Inlet. The deep Atlantic water and large embayments of Amundsen Gulf support high abundances of B. saida across life-history stages and warrant special consideration for industrial planning and conservation initiatives. Our results provide contemporary baselines on marine fish community structure and diversity for the Amundsen Gulf region and provide a basis for evaluating future change and comparisons with neighboring regions.