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Publication year : 0
Thematic : Fisheries
Language : English
Note
Ecosystem management means different things to different people, but the underlying
concept is similar to that of the long-standin,(7 ethic of conservation. Current interest in
marine ecosystem management stems from concerns about overexploitation of world
fisheries and the perceived need for broader perspectives in fisheries management. A
central scientific question is whether the effects of harvesting (top down) or changes in the
physical environment (bottom up) are responsible for major changes in abundance.
Historically, ecology, fisheries biology, oceanography, fisheries management and the
fishing industry have gone somewhat separate ways. Since the 198Os, increasing attention
has been given to multispecies aspects of fisheries, the linkages between oceanography
and fish abundance and more holistic approaches to fisheries management.
Sorting out the causes and effects of fluctuations in fish abundance is complicated by
the lack of reliability of fisheries statistics. Discards, dishonesty and the inherent logistic
difficulties of collecting statistics all combine to confuse interpretation. The overcapacity
of fishing fleets and their unrestricted use are widely recognized as a contributing cause
to overfishing and declines in fish stocks in many parts of the world.
Ecosystem management, as shorthand for more holistic approaches to resource
management, is, from a fisheries management perspective, centred on multispecies
interactions in the context of a variable physical and chemical environment. Broader
perspectives include social, economic and political elements which are best considered
pragmaticaily as a part of the context of fisheries management.
Objectives in marine ecosystem management are varied. From a biological perspective,
an underlying principle of management is commonly assumed to be a sustained yield of
products for human consumption. Whether that should be taken to mean that the yield
. should always be of the same products is less certain. Fishing commonly changes the
relative abundance of species of fishes. Thus, a biological objective should specify the
species mix that is desired.
Concern for the maintenance of global diversity has generated a substantial literature
on threatened and endangered species. In general, it has not been considered likely that
marine fish species could be rendered extinct and greatest attention has been given to
marine mammals, sea birds and sea turtles. The provision of marine parks and sanctuary
areas are obvious first steps in providing a measure of protection, at least for the less
widely ranging species.
Related to the current concepts of ecosystem management are expressions such as
ecosystem health and ecosystem integrity which are given a wide range of different
meanings, none of which are readily translated into operationa language for resource
management. These and similar expressions are best assessed as rhetorical devices. The
essential components of ecosystem management are sustainable yield, maintenance of
biodiversity and protection from the effects of pollution and habitat degradation.
Theory for marine ecosystem management has a long history in fisheries and
ecological literature. Ecological models such as Lotka-Volterra equations, ECOPATH,
trophic cascades and chaos theory do not give practical guidance for managcmcnt. Fleet
interaction and multispecies virtual population analysis models hold more promise for
fisheries managers.
Alaska provides particular opportunities for developing new concepts in fisheries
management. Statistics of catch are good, stock assessments are at the state-of-the-art
level and management has been prudent. Debate is active on the causes of substantial
changes in abundance of many species including marine mammals, because substantial
changes in the fisheries have been accompanied by major changes in oceanographic
conditions.
As elsewhere, the resultant changes may be a consequence of top-down and bottom-up
effects. The bottom part is beyond human control, and ecosystem management is centred
on managing the top-down or fisheries component in the context of special measures oC
protection for particuiar species.
Whether that is a realistic goal depends in part on how much special protection is to
be afforded to which species. Marine mammals, for example, are given high priority for
special protection, but like fisheries they too may have significant roles in shaping the
structure of marine ecosystems. Eventually, ecosystem management must come to grips
with the question of how much protection of particular species is desirable in achieving
optimal use of living marine resources.
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Keywords : Rhinolophus borneensis
Encoded by : Pauline Carmel Joy Eje
