Management of marine species

Abstract

Marine fish and shellfish constitute important natural resources. Provided they are wisely exploited, they are not liable to exhaustion but continue to renew themselves. Wise exploitation requires sound management, and for such management one should be well informed about the factors governing the fluctuations in the stocks and about the costs of exploitation. A century of scientific fisheries research provided a wealth of information on reproduction, migration and growth of commercially important species of fish and shellfish and about the losses the stocks suffer through natural causes such as predation, diseases and parasites, and through the fishery itself. Such information is available for areas which are intensively fished. In fertile waters, the approximate growth increase of fish stocks is some 15 % by weight year−1. If one were to harvest this 15 % only, to be considered as interest on this natural capital, and to leave the capital itself untouched, one could go on fishing for ever. There would be no overfishing or stock depletion. For sound management we need not only ecological data but also information on economic fishery aspects, e. g. on size and power of the fleet, type of fish-finding apparatus installed, costs of netting and wages, fuel required per fishing trip, and on the capital invested. Further we need statistical information on the landings and on the proceeds. Such information is available in countries which participate intensively in fishing. Therefore, one would assume that governments which are well informed by their fishery biologists about fluctuations in stocks of fish and shellfish and by their economists on various aspects of the exploitation would apply sound management to ensure that fishing may continue for many years to come without depletion. A number of examples related to the North East Atlantic area, where intensive fishing is carried out and from where a wealth of scientific information is available, makes clear that cases of sound management are hard to trace.