The importance of managing within‐species diversity in cod and herring fisheries of the north‐western Atlantic

The spatial structure of several exploited species within and among known populations of the Northwest Atlantic is reviewed using past and current knowledge. For each species, the coherence of existing management units with the spatial scale of population dynamics (populations, sub‐populations, and spawning components) is summarized. The implications of this match or mismatch of spatial scales in the maintenance of biodiversity within and among populations are also discussed.