Fish

Freshwater fish are ecologically, socially, and economically important in the Arctic, and more information is known about the distribution and diversity of fish species in Arctic lakes and rivers than is known about other FECs. Within the ecoregions included in this assessment, 100 fish species are known to occur. Large-scale alpha diversity varied among ecoregions, ranging from a single species in the high Arctic to as many as 47 species in Fennoscandia. Fish alpha diversity varied across continents with northern and mountainous ecoregions having lower diversity. Islands (e.g., Iceland, Greenland) had fewer fish species due to biogeographic constraints.

Arctic grayling. Photo: Rostislav Stefanek/Shutterstock.comArctic grayling. Photo: Rostislav Stefanek/Shutterstock.com GIllnet preparation for catching Dolly Varden. Photo: Katrina Liebich, USFWSGIllnet preparation for catching Dolly Varden. Photo: Katrina Liebich, USFWS

Fourteen species of fish had a distributional range across continents - including salmonids, smelts, sticklebacks, freshwater cod, pike, and lamprey. Three additional species (all Salmonids) have been introduced to Fennoscandia and Russia from North America. Longitudinal distribution patterns of fish species showed a marked decline in the Atlantic zone, from generally more than 50 species in North America to many stations with less than 50 species in Fennoscandia. Our analysis also showed that alpha diversity at latitudes above 72°N declined to a single species, Arctic charr, although more species are known to occur.

Arctic Charr. Photo: Dan Bach Kristensen/Shutterstock.comArctic Charr. Photo: Dan Bach Kristensen/Shutterstock.com Brown trout. Photo: Rostislav Stefanek/Shutterstock.comBrown trout. Photo: Rostislav Stefanek/Shutterstock.com

Beta diversity differed across ecoregions, with higher values in Alaska and inland Fennoscandia. The turnover component of beta diversity was dominant in ecoregions in these areas. This indicates that the replacement of species across spatial or environmental gradients drives diversity patterns across a range of ecoregion types in North America and Fennoscandia, including alpine and taiga habitats. The nestedness component of beta diversity was greater only in Iceland, where only three species were represented in the data, and changes in species composition across the region would result from sub-setting the richest fish community. 

Yakut woman serving whitefish. Photo: Tatiana Gasich/Shutterstock.comYakut woman serving whitefish. Photo: Tatiana Gasich/Shutterstock.com Burbot. Photo: Rostislav Stefanek/Shutterstock.comBurbot. Photo: Rostislav Stefanek/Shutterstock.com

While fish are key species in aquatic ecosystems and are important to communities of the North, it is evident that there are significant gaps in monitoring effort and data coverage across the circumpolar region. Although in some cases the spatial extent is limited because existing datasets were not accessible, there remain significant gaps in monitoring effort and coordination of routine monitoring in some areas. Across Canada, for example, a large number of historical studies focused on monitoring commercial or subsistence fisheries, and thus quantified a selection of fish species rather than assessing the diversity of the full assemblage. Furthermore, many sites across North America have only been sampled one time, thus precluding temporal analyses of trends. Similarly, there are large areas that have not been sampled sufficiently to allow for analyses of spatial patterns or temporal trends. Until broader spatial and temporal data coverage is available, the ability to assess changes in biodiversity, especially at large spatial scales, will be limited.

Drying fish. Photo: Joseph CulpDrying fish. Photo: Joseph Culp Photo: Dan Bach Kristensen/Shutterstock.comPhoto: Dan Bach Kristensen/Shutterstock.com

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