Management of multi-species fisheries: From overfishing to sustainability

Abstract

Any form of management adopted for species, ecosystems, or the biosphere must: (1) be consistent with management at other levels of biological organization; (2) account for reality, including the uncertainty of what we do not, or cannot, know; (3) result in living systems within their normal ranges of natural variation; (4) exercise precaution and consider risk in achieving sustainability; (5) be information-based and interdisciplinary; (6) include monitoring and assessment; (7) have clear goals and standards of reference; (8) be limited to controlling human activities; (9) include humans among the components of ecosystems and the biosphere. These nine objectives can be met simultaneously. The form of management that does so is described in this paper in its application to multi-species fisheries. It also applies in the management of fisheries harvesting from single populations, species, ecosystems or the biosphere. Such management would be based on empirically observed sustainability. In this paper, it is demonstrated how sustainable consumption from two groups of species in separate ecosystems is exemplified by the predators that feed on them. Such empirical examples are the result of a wide variety of factors, including the trial-and-error processes of evolution and various risks, including extinction, that impose limits. Implications for management are clear. Consumption rates by humans have been much too high and would have to be reduced significantly to match empirically proven sustainability at its maximum. Commercial takes of fish are far above the mean rates of consumption observed among predatory species in nature. It will be extremely difficult to implement the management that appears to be necessary. Nevertheless, consumption rates beyond the naturally observed limits have not been proven to sustainably avoid long-term risk. (C) 1999 International Council for the Exploration of the Sea.