科研之友
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摘要
Fishing is by nature and design selective, targeting species and sizes that yield the highest economic returns. Manipulation of the selective characteristics of fishing gear has been an important tool to influence the fishing pattern-for example, to minimise capture of certain age groups or to minimise catches of unwanted species. Selective removal of specific species and age groups in preference to others may contribute to changes in the species and size composition of fish communities, alter trophic interactions, and may lead to phenotypic or genotypic changes in harvested stocks. Balanced harvest (BH) is an ecologically based concept that aims to balance fishing mortality across a range of species, stocks and sizes, in proportion to their natural productivity in an ecosystem, so that the relative size and species composition are maintained relative to an unexploited ecosystem. The BH concept suggests that management practices and markets that promote size and species selective fishing should be reconsidered; as such it has been misinterpreted by some as an unselective fishing strategy. However, selectivity in fisheries is complex, and we introduce a multi-level concept of selective fishing to describe and discuss this unrecognized complexity, and examine the feasibility of a BH-type strategy. We conclude that a BH is an interesting concept that merits further exploration to better understand the challenges towards pragmatic implementation. Contrary to some interpretations of the BH concept, its implementation may require even more selective fishing gears and practices.
- 出版日期2016-12
