Dr Kjell Magnus Norderhaug1, Dr Kjell Nedreaas1, Dr Mats Husebråten1, Dr Even Moland1
1Institute Of Marine Research IMR Norway, Flødevigen, Norway
We show that fishery driven predator release was the likely 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 Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we assessed if overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km2 kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods, and introduction of new fish species on the food marked. These fish, including coastal cod (Gadus morhua), Atlantic wolfish (Anarhichas lupus) and haddock (Melanogrammus aeglefinus), were important predators on urchins and the reduction coincided with the urchin bloom. This circumstantial evidence suggest that coastal predatory fish were important in regulating sea urchins, and that a local population dynamics perspective is necessary in management of coastal ecosystems.
Presentation Files – Kjell Magnus Norderhaug
Biography:
My main field of interest is dynamics of benthic coastal ecosystems with particular focus on kelp forest ecology and trophic interactions. I have long experience with environmental monitoring, with particular focus on ecological effects from eutrophication and climate change. Through my work I have coordinated national and international research and monitoring projects. I have conducted field work and cruises, using diving as a scientific tool all along the Norwegian coast. I have long experience with communicating science to the management, society and for educational purposes from an ecosystem perspective.
