Abstract
Abstract The snow crab (Chionoecetes opilio) is a newly established species in the Barents Sea, increasing in both distribution and abundance in recent years. We explore the potential importance of North-east Arctic cod (Gadus morhua) predation in structuring the snow crab population expansion in the Barents Sea, through an analysis of cod stomach content data from 2003 to 2018. Spatio-temporal patterns of snow crab within cod diet are assessed across years, between seasons, as well as ontogenetic trends, including predator–prey size relationships. Snow crab represents a new prey item for cod and in recent years the most dominant demersal crustacean species in cod diet. The proportion of snow crab within cod diet increases over time. Primarily 60–110 cm cod prey upon snow crab, mainly during the summer/autumn season. Our results support the idea that the snow crab is still expanding, shifting distribution north and westwards. Cod has the potential to regulate the snow crab population but is unlikely to be in direct competition with the fishery in the Barents Sea. This work suggests that cod can be used as biological sampling tools together with other monitoring programmes to elucidate how new species may affect predator–prey and food-web dynamics within an ecosystem context.
Highlights
The native habitat of the snow crab (Chionoecetes opilio, Fabricius 1788) is located in the Northern Pacific and adjacent waters of the Chukchi, Eastern Siberian, Laptev, and Beaufort seas, as well as in the North Western Atlantic including waters of western Greenland (Pavlov and Sundet, 2011)
The stomach database ranges from 1984 to date; we focus on data from 2003 onwards as snow crab were not found in cod stomachs prior to this year (Dolgov and Benzik, 2016; Holt et al, 2019) (Figure 1)
Temporal shifts in the contribution of snow crab to the cod diet Prior to 2003 snow crab was not present in the cod diet; in recent years, it has steadily increased from 0.03% in 2003 to 6.5% in 2018 (Figure 2)
Summary
The native habitat of the snow crab (Chionoecetes opilio, Fabricius 1788) is located in the Northern Pacific and adjacent waters of the Chukchi, Eastern Siberian, Laptev, and Beaufort seas, as well as in the North Western Atlantic including waters of western Greenland (Pavlov and Sundet, 2011). The snow crab population has since increased rapidly in both distribution and abundance, maintaining established habitat in areas in the eastern, central, and northwest Barents Sea (Sokolov et al, 2016). VC International Council for the Exploration of the Sea 2021.
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