Impacts of fishing gear on marine benthic habitats
Kaiser, M.J.; Collie, J.S.; Hallam, S.J.; Jennings, S.; Poiner, I.R. (2003). Impacts of fishing gear on marine benthic habitats, in: Sinclair, M. et al. Responsible fisheries in the marine ecosystem. pp. 197-217 In: Sinclair, M.; Valdimarsson, G. (Ed.) (2003). Responsible fisheries in the marine ecosystem. FAO/CABI Publishing: Rome, Cambridge. ISBN 925 104767 7. xviii, 426 pp., more |
| Authors | | Top | - Kaiser, M.J., more
- Collie, J.S.
- Hallam, S.J.
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| Abstract | Fishing affects seabed habitats worldwide. However, these impacts are not uniform and are affected by the spatial and temporal distribution of fishing effort, and vary with the habitat type and environment in which they occur. Different fishing methodologies vary in the degree to which they affect the seabed. Towed bottom-fishing gears and hydraulic harvesting devices re-suspend the upper layers of the sedimentary habitat and hence re-mobilize contaminants and fine particulate matter into the water column. The ecological significance of these fishing effects has not yet been determined. Structurally complex habitats (e.g. sea-grass meadows, biogenic reefs) and those that are relatively undisturbed by natural perturbations (e.g. deep-water mud substrata) are more adversely affected by fishing than unconsolidated sediment habitats that occur in shallowcoastal waters. Structurally complex and stable habitats also have the longest recovery trajectories in terms of the re-colonization of the habitat by the associated fauna. Comparative studies of areas of the sea bed that have experienced different levels of fishing activity demonstrate that chronic fishing disturbance leads to the removal of high-biomass species that arecomposed mostly of emergent seabed organisms. These organisms increase the topographic complexity of the seabed and have been shown to provide shelter for juvenile fishes, reducing their vulnerability to predation. Conversely, scavengers and small-bodied organisms, such as polychaete worms, dominateheavily fished areas. Such a change in habitat may lead to changes in the composition of the resident fish fauna. Fishing also has indirect effects on habitat through the removal of predators that control bio-engineering organisms such as algal-grazing urchins on coral reefs. However, such effects are only manifested in those systems in which the linkages between the main trophic levels are confined to less than ten species. Management regimes that aim to incorporate both fisheries and habitat conservation objectives can be achieved through the appropriate use of a number of approaches, including total and partial exclusion of towed bottom fishing gears, and seasonal and rotational closure techniques. Different managementregimes can only be formulated and tested once objectives and criteria for seabed habitats have been defined. |
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