Cascading effects of over-fishing marine systems
B. Deyoung2005, Trends in ecology & evolution
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Abstract
Profound indirect ecosystem effects of over-fishing have been shown for coastal systems such as coral reefs and kelp forests. A new study from the ecosystem off the Canadian east coast now reveals that the elimination of large predatory fish can also cause marked cascading effects on the pelagic food web. Overall, the view emerges that, in a range of marine ecosystems, the effects of fisheries extend well beyond the collapse of fish exploited stocks.
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ices.dk
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Comparing pristine and depleted ecosystems : the Sørfjord, Norway vs the Gulf of St. Lawrence, Canada. Effects of intense fisheries on marine ecosystems. ICES CM 2007/D:18
2007
The Sørfjord, Norway, and the Gulf of St. Lawrence, Canada, are two sub-arctic ecosystems with similar trophic structure. However, in the Gulf of St. Lawrence, severe exploitation of groundfish stocks has lead to important shifts in the trophic structure. In the Sørfjord, the situation is different: fishing pressure is much lighter. Our hypothesis is that overexploitation leads to changes in the trophic structure and severely alters the resilience of ecosystems. Based on the same modelling approach (Ecopath with Ecosim) the food web structure was compared, using different ecosystem indicators. Patterns of food web structure and trophodynamics were contrasted. The keystone species in both ecosystems is cod. In both ecosystems, forage fish are also important. Even after similar environmental changes in both ecosystems, and after a reduction of fishing pressure in the Gulf of St. Lawrence, there is no recovery of cod stocks in this ecosystem. In the Sørfjord, after different perturbati...
The role of a dominant predator in shaping biodiversity over space and time in a marine ecosystem
Journal of Animal Ecology, 2015
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Advances in Ecological Research, 2012
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