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Reef Fisheries.

Ecologists studying coral reefs and their fishes are only rarely studying pristine systems. The overwhelming majority of tropical reefs have been influenced by humans, most often through exploitation of food resources, including both fishes and invertebrates. As human populations continue to grow in tropical regions, fishing pressure in coral reef communities will only intensify. This human perturbation raises the stakes for answering many questions of interest to both ecologists and fisheries scientists. How does the strength of density dependent growth or mortality in the benthic versus planktonic stages of the life cycle affect the success of different forms of fisheries management (e.g., fisheries reserves versus limiting catch)? How do life history and oceanographic features determine population sources and sinks, and thus the most appropriate locations for fished versus protected areas? What might be the indirect effects of removing target species from different trophic levels? Does fishing initiate shifts from a coral- to an algal-dominated community? Does fishing remove important nutrient sources so as to lower overall ecosystem productivity?

Reef fisheries, a multi-authored volume edited by Nicholas V. C. Polunin and Callum M. Roberts, sets out to summarize our current knowledge in this field, and lay the groundwork for future research and fisheries management. The book is about evenly divided among three major topics: the basic biology and ecology of target species (principally fishes); fisheries biology (effects of fishing intensity and gear on populations and ecosystems); and the human ecology of reef fisheries and management systems.

The book opens with an interesting overview by John L. Munro, one of the major contributors to our current understanding of reef fisheries. Munro describes the structure and geography of tropical reef ecosystems, estimates potential global annual harvest, and discusses ecological shifts from predators to herbivores that occur in severely overfished ecosystems.

The four chapters that follow focus on the ecology of reef fishes and their ecosystems. This section is hampered by the much more extensive treatment of these topics in The ecology of fishes on coral reefs, published in 1991 (Sale, Peter E Academic Press, San Diego, California). Though there is inevitably considerable overlap, particularly in the area of larval biology and population dynamics, the editors of Reef fisheries successfully fill some gaps left in the earlier volume. Particularly useful is Yvonne J. Sadovy's extensive review of growth, sex change, and reproductive output in those species that are the target of fishing. In an excellent chapter, Roberts discusses population regulation in reef fishes, offering a very nice synthesis of the current literature, as well as some suggestions (useful for both ecologists and fisheries biologists) for future research in this area. Polunin discusses ecosystem productivity modeling as a tool for predicting fish productivity. However, so little of the necessary data are available that the exercise seems rather futile. Additionally, important ecological processes, such as the potential for nutrient enrichment to shorten or alter food chains, are ignored when constructing predictions on factors affecting fish productivity.

The second major section deals with fishing methods and intensity, and how these impact targeted populations and their ecological communities. A particularly interesting chapter, authored by Simon Jennings and John M. Lock, reviews studies on population and ecosystem effects of reef fishing. These effects range from changes in sex ratios in sequential hermaphrodites to shifts towards dominance by invertebrate herbivores through fishing mortality of their fish predators and competitors. Richard S. Appeldoorn provides an overview of fisheries models and how they might apply in the multispecies fisheries of tropical reef systems. Not surprisingly, it is impossible for a single chapter to provide a truly adequate review of this topic; to appreciate the assumptions and mechanisms of these models, one needs to go to the primary literature. However, it appears that many of the important population and community effects discussed in earlier chapters, also the subject of great interest among ecologists, have yet to be adequately incorporated into fisheries models.

The third section focuses on fisheries management systems, both traditional and modern. Reef fisheries are in a state of rapid transition, with a break down of many traditional, local management systems but without an adequate replacement on national levels. Informative and thought-provoking discussions on these topics are provided by Kenneth Ruddle on traditional management, and by Timothy J. H. Adams on modern management. The use of fishery reserves is explored in a very interesting chapter by James A. Bohnsack. "Protected areas" or "replenishment reserves" have become a management tool strongly supported by marine conservation biologists. Such reserves have the advantages of being relatively easy to enforce, protecting the entire ecosystem (and thus providing economic opportunities in tourism), and providing a refuge for large, highly fecund individuals. With these advantages come the challenges (not fully developed in this chapter) of identifying source populations within which to locate reserves, providing data showing that they increase fisheries yields outside, and creating the local support necessary for the establishment and protection of the reserve. The book concludes with a "progress and future directions" chapter by Polunin, Roberts, and Daniel Pauly, which is admirably upbeat considering the scientific, economic, and social challenges faced by those interested in successful management and protection of reef fishes and their habitats.

Overall, this is a book well worth reading not only for fisheries biologists but for those interested in the ecology and conservation of coral reefs or tropical fishes. As has been said of restoration ecology, fisheries management is the ultimate test of our understanding of population and community ecology. Unfortunately, the very expensive price for this book may limit its readership, particularly in the developing countries within which most reef fisheries exist.

MYRA J. SHULMAN Cornell University Section of Ecology and Systematics Ithaca, New York 14853
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Author:Shulman, Myra J.
Publication:Ecology
Article Type:Book Review
Date:Oct 1, 1997
Words:948
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