A Solution to the Conflict Between Maximizing Groundfish Yield and Maintaining Biodiversity
Albert V. Tyler
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There is a practical conflict between the goals of biodiversity maintenance and maximization of long-term fishery yields. It is not possible to maximize both simultaneously. On one hand, how to achieve long-term maximum yields while accounting for species interactions cannot be formulated because of variable relationships among species. On the other hand, it is known that catch rates tuned to the most productive species will bring about decreases in biomasses of less productive species taken as bycatch. This means diversity will decrease. Yet the long-term yields of economically valuable assemblages are likely dependent on the very diversity that is threatened by maximizing yields. A comparison of groundfish assemblages of continental shelves from the North Atlantic Ocean demonstrates that whole assemblages have declined—not just a few economically valuable species. An assemblage maintenance approach may be the only method of achieving multispecies persistence. A program of assemblage maintenance is suggested that reduces destructive exploitation risk while achieving economically viable levels of fisheries yields. The proposal involves setting up areas of contrasting fishing effort, with areas based on species stock structure and assemblage maps. It might be possible to hold part of a region with present effort levels, with increases encouraged in another part. The establishment of management areas would be followed by monitoring commercial catches of selected species, and by a program of research surveys that included assemblage analysis. Criteria are presented for adjustments of catch rates in response to assemblage changes related to fishing effort.
- Item number: AK-SG-99-01aa
- Year: 1999
- DOI: https://doi.org/10.4027/eafm.1999.27