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Discards and bycatch issues in the ecosystem approach.
Bellido J M
Instituto Español de Oceanografía, Centro Oceanográfico de Murcia (IEO), C/ Varadero 1, Apdo 22. San Pedro del Pinatar. 30740 Murcia (Spain).
Nowadays it is evident that discard practices constitute a purposeless waste of valuable living resources which plays an important role in the depletion of fish populations. Furthermore, discard practices may produce a number of adverse ecological impacts due to ecosystem changes in the overall structure of trophic webs and habitats which could risk the sustainability of fisheries. The capture of juvenile individuals of target species results in lower catch opportunities for those species in the future (growth overfishing) as well as a reduction in the spawning biomass since the juveniles caught will not contribute in future spawning seasons. The discard of mature individuals of target species represents a waste and immediately reduces the spawning biomass of that stock (spawning overfishing). The capture and discard of fish, crustacean, sea bird or sea mammal species which are not targeted by fisheries, is an unnecessary negative impact on the marine ecosystem as it affects both its functioning as well as its biodiversity negatively without providing any benefits to society. As a consequence, the fishing industry is also affected negatively in two main ways: firstly because fish which are killed without contributing to the income of the sector will not contribute to the income in the future either. If the fish were left to live and grow in the sea they would be available as an economic resource in the future; secondly, the fishing industry will be affected because in the longer term it is dependent on a healthy marine ecosystem.
The challenge is to contribute to the minimization of the adverse ecological and environmental impact of fishing activities (on board as well as on shore), by helping fleets to comply with the so-called “no-discards” and “zero-waste” policies of European Commission. Reduction of unwanted by-catch by better understanding of fish behaviour, avoiding fishing mortality on non-commercial species and permitting easy location of species demanded by industry (with subsequent reduction of fuel consumption) is one of