Comparing pristine and depleted ecosystems : the Sørfjord, Norway vs the Gulf of St. Lawrence, Canada. Effects of intense fisheries on marine ecosystems ...

• Main Authors: Morissette, Lyne, Pedersen, Torstein, Nilsen, Marianne
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: ASC 2007 - Theme session D 2024
• Subjects: Ecosystem observation, processes and dynamics; Arctic
• Online Access: https://dx.doi.org/10.17895/ices.pub.25257655.v1; https://ices-library.figshare.com/articles/conference_contribution/Comparing_pristine_and_depleted_ecosystems_the_S_rfjord_Norway_vs_the_Gulf_of_St_Lawrence_Canada_Effects_of_intense_fisheries_on_marine_ecosystems/25257655/1

No abstracts are to be cited without prior reference to the author.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 ...