Issue 15: Excessive bycatch and discards |
| Description |
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Discards are fish that are caught and returned to the sea (usually dead or injured) or fish that are landed but are not eaten sold or used in any other productive manner. Bycatch refers to the capture of species that are not the target species of the fishery and may include marine mammals and seabirds. Bycatch is only a problem if the fish are discarded or are of a threatened species. Discards are due to a wide variety of reasons, including non-marketability of catches, fishery regulations, management by quotas or Total Allowable Catch (particularly in a mixed species fishery) and non-selectivity of fishing gear. The proportion of catch discarded varies widely in different fisheries; in some trawl fisheries for high value prawns as much as 90% of the catch is discarded, whereas in an artisanal subsistence fishery the figure will be close to zero. It is estimated that some 30% of world fish catches are discarded. References Alverson, D.L et al 1994. A global assessment of fisheries by-catch and discards. FAO Technical Paper No. 339. Rome 233 pp. Northridge, S.P. 1991. An updated world review of interactions between marine mammals and fisheries. FAO Fisheries Technical Paper, No. 251, Suppl. 1. Rome, FAO. 1991. 58pp. |
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GIWA definition |
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Bycatch refers to the incidental capture of fish or other animals that are not the target of the fisheries. Discards refers to dead fish or other animals that are returned to the sea. |
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Environmental impacts |
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1. Changes in food webs favouring scavengers by wastage of bycatch and discards 2. Changes in biological community structure due to overexploitation/depletion of one or more key species 3. Impacts on Spawning Stock Biomass and on future recruitment due to discarding of juveniles 4. Potentially severe impacts on ecosystem |
Indicators | |
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The following are environmental impact indicators for excessive bycatch and discards. Select the environmental impact indicators that are relevant from the list below and input data into the appropriate indicator sheets. | |
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