Integrating the scale of population processes into fisheries management, as illustrated in the sandeel, Ammodytes marinus

Aggregations of site-attached populations can show marked differences in density due to variation in local productivity and mortality processes. Matching management actions to the scale of biological processes is therefore important for sustainable fisheries management. This study examined the adequacy and appropriate scale of a spatially explicit management regime for sandeel, Ammodytes marinus, in the North Sea. Information from biophysical model simulations of larval transport and otolith chemistry was used to estimate the scale of mixing among aggregations. Together, these approaches indicated that there was negligible exchange of pre-settled sandeel among aggregations >200km apart. Additionally, a re-analysis of tag-recapture experiments and distribution data indicated that the dispersive range decreased further after settlement. Significant differences in length at maturity and year-class strength not only reflect the limited mixing across the North Sea, but also point to regional differences in productivity and thereby vulnerability to fishing pressure. We conclude that the current management regime comprised of multiple assessment areas enable these differences to be considered in advice on annual fishing quotas.