Publication Date:
2015-05-30
Description:
A model combining qualitative and historical quantitative data in an innovative rule-based fuzzy cognitive map framework is used to assess and compare the long-term bioeconomic impact of adopting gear modifications aimed at reducing bycatch in the Portuguese crustacean trawl fishery. The impact of codend-related changes (mesh size and shape) and the introduction of a sorting device (sorting grid system) on the main target crustacean species (deepwater rose shrimp Parapenaeus longirostris and Norway lobster Nephrops norvegicus ) and the main fish bycatch species (blue whiting Micromesistius poutassou , horse mackerel Trachurus trachurus , and European hake Merluccius merluccius ) were evaluated. Horse mackerel was the only fish species for which changing codends negatively affected landings per unit of effort by large percentages. The use of a sorting grid system, only evaluated for blue whiting and Norway lobster, led to a strong decrease in landings per unit of effort, especially for the former species. The impact of gear alterations was negligible on fish spawning-stock biomass, but was significant for crustaceans, particularly rose shrimp. A straightforward evaluation of the economic impact (fishers' revenues) of the three bycatch reduction options showed these to be negligible or small.
Print ISSN:
1054-3139
Electronic ISSN:
1095-9289
Topics:
Biology
,
Geosciences
,
Physics
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