Fishing gears used to catch bottom-dwelling fish and shellfish often disturb both the seabed and the organisms living within or on it. The potential impact of this disturbance has become a subject of heated debate because of the widespread use of bottom fishing gear and the ability to visualize its effects with underwater photography. To address this controversy, a team of international scientists, including University of Rhode Island fisheries oceanographer Jeremy S. Collie, analyzed data from a number of separate fishing impact studies and have come to some surprising conclusions. The results of Collies meta-analysis, which is the summary of multiple, independent studies to detect general relationships, are reported in a recent issue of the Journal of Animal Ecology. The scientific team found 57 different observations from 39 separate studies on the effects of fishing disturbance on seafloor organisms around the world.

The study reveals that the type of fishing gear used has a significant effect on the degree of disturbance to sediment organisms. Inter-tidal dredging has the most negative impact, followed by scallop dredging and inter-tidal raking. Otter trawling and beam trawling are less negative, which is not surprising as dredges tend to penetrate deeper into the sediments than trawls.

Habitat type was also considered with the most negative impacts occurring in muddy sand and gravel habitats. Surprisingly, the least impact is observed in mud habitats, not sand. The studies revealed that beam trawling in sand habitats has less impact than the other gear types and other habitats. As expected, largest negative impacts occur in biogenic habitats, which are largely composed of relatively slow growing species, such as sponges and corals.

The populations affected by bottom fishing range from corals, sea anemones, lobsters, shrimp, and crabs being most negatively affected, to starfishes and aquatic earthworms being the leas
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Contact: Lisa Cugini
lcugini@gso.uri.edu
401-874-6642
University of Rhode Island
26-Jun-2001