Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic |
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| Authors: | Kjell Magnus Norderhaug Kjell Nedreaas Mats Huserbrten Even Moland |
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| Institution: | 1.Institute of Marine Research IMR, Norway, Nye Flødevigveien 20, 4817 His, Norway ;2.University of Oslo Norway, Oslo, Norway ;3.Institute of Marine Research, Norway, Nordnesgaten 33, 5005 Bergen, Norway ;4.Institute of Marine Research, Norway, Nordnesgaten 50, 5005 Bergen, Norway ;5.Institute of Marine Research, Norway, Nye Flødevigveien 20, 4817 His, Norway ;6.Centre for Coastal Research (CCR), University of Agder, Kristiansand, Norway |
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| Abstract: | 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 Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km2 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. |
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| Keywords: | Coastal fisheries Fisheries management Kelp forest Regime shifts Sea urchin grazing |
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