Evaluating The Effectiveness Of Biological Reference Points In Conserving Reproductive Potential

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The management for Northeast Arctic (NA) cod defines both limit and threshold reference points for spawner biomass (Blim and Bpa, respectively). The current value of Blim (112,000 t) corresponds to the lowest SB value in the time series (i.e., Bloss). The Bpa value has been set equal to the former MBAL value of 500,000 t, however, it is impossible to unambiguously identify a value below which recruitment is impaired from the S/R relationship that was used to develop these reference points (Fig. 1a). For example, the four years having the highest recruitment (1950, 1963, 1964 and 1970) were associated with spawner biomass (SB) values that were considerably less than the Bpa (Fig. 1a). This variability complicates defining a limit reference point. Furthermore, because the majority of SB values in this plot were estimated using knife-edge maturity ogives (1946-1981) and constant weight-at-age values (1946-1982), the S/R relationship and the reference points derived from it are insensitive to the true effect of variation in growth on the relationship.