ESSENTIAL FISH HABITAT AND THE EFFECTIVE DESIGN OF MARINE RESERVES: APPLICATIONS FOR MARINE ORNAMENTAL FISHES

Alan M. Friedlander and David A. Ziemann

The Oceanic Institute, 41-202 Kalanianaole Hwy., 
Waimanalo, HI 96795 USA
ziemannda@oceanicinstitute.org

Aquarium Sciences and Conservation , in press

Extensive and unregulated harvest of marine ornamental fishes can lead to localized depletion of target species. Moreover, harvest can result in habitat degradation from diver damage and inappropriate collecting techniques. One potential solution to these problems is the creation of marine reserves where fishing and other extractive activities are prohibited. Marine reserves have been shown to increase fish abundance and protect ecosystems from habitat destruction associated with fishing. Marine reserves not only protect species inside the reserve but they can also increase fish abundance in adjacent areas. In order for marine reserves to be effective, managers must consider the relationship between fishes and their associated habitats. Many reef fishes depend upon the coral reef for food, shelter, or as preferred habitat for settling larvae. Reef fish assemblages can be influenced by the physical structure of the associated reef. Results from studies in Hawaii have shown that fish assemblages with high diversity and abundance are associated with habitats of high structural complexity. A relationship between fish size and reef complexity may suggest the importance of shelter as a refuge for certain fishes in avoiding predation. Fishes are also noted to be more abundant and diverse nearer to reef edges. The sharp interfaces that edges provide between habitats with different physical and biological properties often results in locally increased "traffic" and abundance of predators, prey, spawners, and migrators. Some reef fishes spawn in large aggregations at sites that are predictable in both space and time. Many species tend to aggregate in structurally complex habitats to reduce their predation risk during the aggregation period. Our research had shown increases in the average size and improvements in the sex ratio of groupers after a spawning aggregation closure went into effect in the US Virgin Islands. These data suggest that protection of spawning aggregations is a sound management strategy with considerable potential for aiding in the sustainable use of reef resources. Marine reserves offer a promising alternative to western fisheries management that normally relies on catch limits or restriction on gear and/or effort. Marine fisheries reserves are thought to enhance fisheries by protecting spawning stocks, providing refugia for prerecruits and by exporting biomass to adjacent fishing grounds. Marine reserves also have many non-fisheries benefits, such as protecting biodiversity and ecosystem structure, serving as biological reference areas, and providing non-consumptive recreational activities. Reserve designs need to consider the habitat requirements and life histories of the species of interest as well as the extent of fishing pressure in the area and the degree of enforcement. If protective areas are to be effective, they must include the diversity of habitats necessary to accommodate the wide range of fish species that are of interest to the marine ornamental fish trade.