Atlantic herring (Clupea harengus): Photo: Institute of Marine Research, Norway

Total biomass

Zero group fish are important consumers on plankton and are prey of other predators, and, therefore, are important for transfer of energy between trophic levels in the ecosystem. Estimated total biomass of 0-group fish species (cod, haddock, herring, capelin, polar cod, and redfish) was 1.92 million tonnes during August-September 2017; slightly above the long term mean of 1.76 million tonnes (Fig 3.5.1). Biomass was dominated by cod and haddock, and mostly distributed in central and northern-central parts of the Barents Sea.

Capelin, polar cod, young herring, and blue whiting constitute the bulk of pelagic fish biomass in the Barents Sea. Note that the acoustic target strength for blue whiting has been changed recently, and the time series has been recalculated. Total biomass of the main pelagic species (age 1 and older fish) in the Barents Sea in 1986-2017 has fluctuated between 0.5 and 9 million tonnes; mainly driven by fluctuations of the capelin stock. In 2017, cumulative biomass of capelin, herring, polar cod, and blue whiting was close to the long-term mean (Fig. 3.5.2).

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