Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic

In this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km(2)kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet. These fish were important predators on urchins and the reduction coincided with the urchin bloom. From this circumstantial evidence, we hypothesize that coastal predatory fish were important in regulating sea urchins, and that a local population dynamics perspective is necessary in management of coastal ecosystems.

Automated summary

The article proposes the fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic, discussing the overgrazing of kelp forests due to sea urchin bloom and likely depletion of predatory coastal fish stocks by coastal fisheries modernization. It hypothesizes the importance of coastal predatory fish in regulating sea urchins and the necessity of a local population dynamics perspective in managing coastal ecosystems.