The long-term variation of the mean biomass of the NW, SW and the total Barents Sea show strong correlations (Figure 5.3.1). This might indicate that the western Barents Sea are driven by a factor common for the total Barents Sea. If comparing fluctuations of bottom temperature (Figure 5.3.1) with the benthos biomass (Figure 5.3.2) both shows clear decreasing values during 2007-2010. But previous studies show that benthos has a delay of approximately 3-7 years for macrobenthos to environmental variables (Lyubina et al., 2013; Denisenko, 2013), but with the more long-lived megabenthos, we suggest this delay to no less than 7 years.
Expected changes 2017
Natural mortality of capelin is currently very high. The main predator for capelin is cod. The size of the cod stock is probably a main factor in the decline in capelin stock size. However, the relationship between changes in stock size of cod and capelin is not very strong. Historical data show that the probability of increase of capelin stock to a high level is low when the cod stock is large (Figure 5.2.1).
The 2016 capelin year class was strong at the 0-group stage and preliminary reports from the 2017 winter survey state that 1-group capelin was abundant and widely distributed.
Oceanic systems have a “longer memory” than atmospheric systems. Thus, a priori, it seems feasible to predict oceanic temperatures realistically and much further ahead than atmospheric weather predictions. However, the prediction is complicated due to variations being governed by processes originating both externally and locally, which operate at different time-scales. Thus, both slow-moving advective propagation and rapid barotropic responses resulting from large-scale changes in air pressure must be considered.