Publisher : International Council for the Exploration of the Sea
Place of publication :
Publication year : 2000
Thematic : Fisheries
Language : English
Note
Ecosystem considerations may be incorporated into fisheries management by modifying
existing overfishing paradigms or by developing new approaches to account for
ecosystem structure and function in relation to harvesting. Although existing concepts
of overfishing have a strong theoretical basis for evaluating policy choices and much
practical use, they do not provide direct guidance on issues such as biodiversity, serial
depletion, habitat degradation, and changes in the food web caused by fishing. There
is, however, little basis for defining optimum fishing by using related metrics such as
diversity indices, slopes of size or diversity spectra, or average trophic level of the
catch, and these may produce ambiguous results. If ecosystem-based overfishing
concepts are to assume a greater role in management, unambiguous, quantifiable,
and predictive measures of ecosystem state and flux must be developed to index:
(1) biomass and production by the ecosystem and relationships among its parts,
(2) diversity at different levels of organization, (3) patterns of resource variability, and
(4) social and economic benefits. Ecosystem considerations do not need to substitute
for existing overfishing concepts. Instead, they should be used to evaluate and modify
primary management guidance for important fisheries and species. In practice, they
emphasize the need to manage fishing capacity, supported by broader use of technical
measures such as marine protected areas and gear restrictions.
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Encoded by : Christian Elloran
