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Effects of Trawling and Dredging on Seafloor Habitat
currently available to support efforts to improve the management of the effects of fishing gear on seafloor habitats. Specific recommendations for making the best use of current information and suggestions for research are provided below.
The following recommendations fall into three categories: 1) interpretation and use of existing data; 2)integration of management options; and 3) policy issues raised by existing legislation. Recommendations for research appear at the end of this section.
Interpretation and Use of Existing Data
Fishery managers should evaluate the effects of trawling based on the known responses of specific habitat types and species to disturbance by different fishing gears and intensity of fishing effort, even when region-specific studies are unavailable. The direct responses of benthic communities to trawling and dredging (Chapter 3) are consistent with ecological models of how biological communities and ecosystems respond to acute and chronic physical disturbance. Although area-specific studies on the effect of trawling and dredging gear will allow more targeted management approaches, adequate information is available to address fishing effects on seafloor habitat. Predictions developed from common trends observed in comparable habitats will provide reasonable estimates of fishing effects to serve as the basis for management. Estimates should be revised as more site-specific information becomes available. An adaptive management strategy could be used both to reduce the effects in the short-term and to provide additional information for improving management in the long-term.
The National Marine Fisheries Service and its partner agencies should integrate existing data on seabed characteristics, fishing effort, and catch statistics to provide geographic databases for major fishing grounds. The potential consequences of fishing can be most efficiently assessed by the simultaneous and consistent presentation of all available data on the characteristics of the seabed and fishing effort. Although some data exist on habitat characteristics and on the location and intensity of fishing (Chapter 4), the available data have been prepared by different agencies, in different formats, at variable levels of resolution, and are collected in separate archives. Integration of these databases into a single, geographic information system will assist managers in evaluating regional needs for habitat conservation.
Integration of Management Options
Management of the effects of trawling and dredging should be tailored to the specific requirements of the habitat and the fishery through a balanced combination of the following management tools.
Fishing effort reductions. Effort reduction is the cornerstone of managing the ecological effects of fishing, including, but not limited to, effects on habitat. Other management tools (gear restrictions or modifications and closed areas) may also require effort reduction to achieve maximum benefit. However, effort reduction alone might not be sufficient to reduce effects in highly structured habitats where there is low potential for recovery.
Modifications of gear design or restrictions in gear type. Disturbance depends on the extent of contact of the gear with the seafloor; gear designs that minimize bottom contact can reduce habitat disturbance. In addition, shifts to a different gear type or operational mode can be considered, but the social, economic, and ecological consequences of gear reallocation should be recognized and addressed.
Establishment of areas closed to fishing. Closed areas effectively protect biogenic habitats (e.g., corals, bryozoans, hydroids, sponges, seagrass beds) that are damaged by even minimal fishing.
The appropriate combination of management approaches will depend on the characteristics of the ecosystem and the fishery—habitat type, resident seafloor species, frequency and distribution of fishing, gear type and usage, and the socioeconomics of the fishery. Each characteristic should be evaluated during development of a mitigation strategy.
The regional fishery management councils should use comparative risk assessment to identify and evaluate risks to seafloor habitats and to rank