The evolution of bottom trawling impact on North Sea flatfish populations

Flatfish has been exploited commercially since the late medieval time. The history of exploitation is closely linked to the evolution of bottom trawling. Here we reconstruct the history of the flatfish fishery and the impact on the population biology based on a variety of sources including historic documents, flatfish remains in archaeological excavations and population modelling. The historic development in intensity and spatial extend of bottom trawling is presented. The selectivity of the fisheries is inferred from the fishing gear and mesh size used and the spatial overlap of the fisheries and the various life history stages - eggs and larvae on spawning grounds, early juveniles on nursery grounds, late juvenile and adult feeding grounds - and the seasonal migrations between spawning and feeding grounds. The presentation will pay particular attention to how trawling may have affected density-dependent processes at different phases during the life cycle and the fisheries-induced evolutionary changes.