Some future perspectives for assessment and management of Mediterranean fisheries
J.F. Caddy

The paper starts with a brief history of management of Mediterranean fisheries, with emphasis on the activities of the General Fisheries Council for the Mediterranean (GFCM): an intergovernmental organization that has been concerned with fisheries management in the region since the 1950's. The early concerns of the Council with fleet overcapacity, and hence overfishing; and with fishing pressure on the inshore nursery areas, and hence the possible use of closures; both remain priorities for discussion. The demersal fisheries of the Mediterranean are multispecies, and the problem this poses for single species management is reviewed, especially with regard to measures such as the imposition of a uniform mesh size for trawl cod-ends. A categorization of demersal fish based on size at maturity and position in the food chain is suggested. An assessment framework placing emphasis on maintaining spawning stock biomass and on stock-recruit relationships, rather than on maximizing yield per recruit, is suggested as a more appropriate basis for scientific management. The small mesh sizes currently used, although negative in impact, especially in their effect on the yield per recruit, with catch dominated by the early age groups, may have incidentally provided some protection for older, mature age groups migrating out of the shallow water trawl fishery. It is hypothesised that this could partly account for often sustained recruitment under conditions of high fishing mortality on the immature age groups. This new paradigm attempts to account for continued survival of fisheries which are targeted on immature age groups, and some further implications of this paradigm are discussed. Under the above circumstances, a research strategy which places less emphasis on using the von Bertalanffy growth function is advised; this should be replaced in yield models by vectors of weight at age, which better reflect the initial weights of the early recruited age groups, which do not appear to correspond well to the expected sizes with the above model. The probability that environmental conditions in the Mediterranean are changing is alluded to. A strategy is suggested for statistical sampling and modelling in support of the management of demersal fish resources in the Mediterranean.

Keywords: Fishery management, stock assessment.
Contents of this volume Sci. Mar. 57(2-3) : 121-130 Back PDF
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