Changes in a benthic megafaunal community due to disturbance from bottom fishing and the establishment of a fishery closure
Asch, R.G.; Collie, J.S. (2008). Changes in a benthic megafaunal community due to disturbance from bottom fishing and the establishment of a fishery closure. Fish. Bull. 106(4): 438-456
In: Fishery Bulletin. US Government Printing Office: Washington, D.C.. ISSN 0090-0656; e-ISSN 1937-4518, more
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| Abstract |
Trawling and dredging on Georges Bank (northwest Atlantic Ocean) have altered the cover of colonial epifauna, as surveyed through in situ photography. A total of 454 photographs were analyzed from areas with gravel substrate between 1994 and 2000 at depths of 40-50 m and 80-90 m. The cover of hydroids, bushy bryozoans, sponges, and tubeworms was generally higher at sites undisturbed by fishing than at sites classifiedas disturbed. The magnitude and significance of this effect depended on depth and year. Encrusting bryozoanswere the only type of colonial epifauna positively affected by bottom fishing. Species richness of noncolonialepifauna declined with increased bottom fishing, but Simpson’s index of diversity typically peaked at intermediatelevels of habitat disturbance. Species that were more abundant at undisturbed sites possessed characteristicsthat made them vulnerable to bottom fishing. These characteristics include emergent growth forms, soft body parts, low motility, use of complex microhabitats, long life spans, slow growth, and larval dispersal over short distances. After the prohibition of bottom fishing at one site, both colonial and noncolonial species increased in abundance. Populations of most taxa took two years or more to increase after the fishing closure. This finding indicates that bottom fishing needs to be reduced to infrequent intervals to sustain the benthic species composition of Georges Bank at a high level of biodiversity and abundance. |
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