engleski

Future of marine resources management

Fish landings in the Adriatic Sea are experiencing a downward trend, similarly to all other coastal seas. What is the maximum sustainable yield (MSY) for each, or at least majority of species, of fish living in the Adriatic Sea? This question has been left unanswered concerning any marine ecosystem for 50 years since the concept has been introduced. Obviously, the question is difficult to answer (it will be shown why). The prospect of ever finding the solution seemed even bleaker than one would expect. Although the solution has been found for an isolated population of fish, its applicability has been heavily criticized due to a complexity of a marine ecosystem. So, instead of generalizing the solution to a complex marine food web, the concept has been essentially called off. In its place another concept has been proposed: ecologically sustainable yield (*). This concept, being very hazy, is subject to so many arbitrary interpretations that efforts against extinction for a number of threatened species have been significantly weakened. I shall reintroduce the concept of MSY. As a reference, first a well known solution for a single isolated population is summarized. Then the complexity of an ecosystem is gradually increased and effects will be discussed which are either expected or have been already documented in marine ecosystems, including the Adriatic Sea. Equipped with these simple examples, an unusual assumption is made which leads to a general solution for any marine ecosystem. The solution is not optimal but it is an order of magnitude better than the best solution presently implemented anywhere, including the Adriatic Sea. Since the solution is easy to implement, it will be the next step in the management of the fish stock in marine ecosystems. -.- (*) According to Zabel et al., (Ecologically sustainable yield. American Scientist, 91(2003), 150-158) an ecologically sustainable yield (ESY) is the yield that an ecosystem can sustain without shifting to an undesirable state. Although "an undesirable state" is a subject of hot discussions with no prospect of an agreement, the definition is not unique in the sense that it includes infinity of solutions inluding the MSY.

maximum sustainable yield; ecologically sustainable yield; marine ecosystem

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