Zooplankton: Calanus finmarchicus
Unlike the data on the NAO and cod, regime shifts in the abundance ofC. finmarchicus changed little with changes in λ (Fig. 3). At hazard rates of 10 through 50, four regimes were distinguished. Focusing on those at λ=25, the earliest supported the highest average yearly abundance of C. finmarchicus in the time series, declining by ~75% in the second regime (1982-1996). The yearly abundance during the third regime (1997-2007) declined further still, before increasing back to the level of the second regime during the fourth regime (2008 to 2017).