Do scyphozoan jellyfish limit the habitat of pelagic species in the Barents Sea during the late feeding period?

Uncovering the relationship between changes in jellyfish abundance and the biological response in the Barents Sea is crucial to understanding the potential effects of jellyfish blooms on ecosystems in general and commercially important fish stocks in particular. The data from autumn surveys (acoustic capelin survey, 0-group survey, and ecosystem survey) were used to explore the effects of jellyfish (i.e. mostly Cyanea capillata) on krill, 0-group fish (capelin, herring, cod, haddock, polar cod, and redfish), and pelagic fish stocks (older capelin, herring, blue whiting, and lumpfish). The temporal and spatial patterns of the jellyfish, krill, and 0-group fish distributions reflected differences in the drift of these organisms with the inflow of Atlantic waters. During 1993-2013, jellyfish were present in two waves in the Barents Sea, namely, in the early 2000s and at the end of the studied period. In the 1990s, jellyfish were found at an average of 40% of stations, whereas in the 2000s, they were found at an average of 80% of stations. The increased occupation area led to increased overlap with other components of the pelagic community. The co-occurrence of the averaged and high concentrations of jellyfish and other studied species/groups indicated a highly productive area most likely defined by ocean currents. The results indicated a lack of robust evidence for the hypothesis that scyphozoan jellyfish limit the habitat of species in the Barents Sea during the late feeding period. However, catches of certain species appear to level off or decrease for notably high catches of jellyfish.