An adaptive management approach to an octocoral fishery based on the Beverton-Holt model
- 228 Downloads
Coral reef species are frequently the focus of bio-prospecting, and when promising bioactive compounds are identified there is often a need for the development of responsible harvesting based on relatively limited data. The Caribbean gorgonian Pseudopterogorgia elisabethae has been harvested in the Bahamas for over a decade. Data on population age structure and growth rates in conjunction with harvest data provide an opportunity to compare fishery practices and outcomes to those suggested by a Beverton-Holt fishery model. The model suggests a minimum colony size limit of 7–9 years of age (21–28 cm height), which would allow each colony 2–4 years of reproduction prior to harvesting. The Beverton-Holt model assumes that colonies at or above the minimum size limit are completely removed. In the P. elisabethae fishery, colonies are partially clipped and can be repeatedly harvested. Linear growth of surviving colonies was up to 3 times that predicted for colonies that were not harvested and biomass increase was up to 9 times greater than that predicted for undisturbed colonies. The survival of harvested colonies and compensatory growth increases yield, and yields at sites that had previously been harvested were generally greater than predicted by the Beverton-Holt model. The model also assumes recruitment is independent of fishing intensity, but lower numbers of young colonies in the fished populations, compared to unfished populations, suggest possible negative effects of the harvest on reproduction. This suggests the need for longer intervals between harvests. Because it can be developed from data that can be collected at a single time, the Beverton-Holt model provides a rational starting point for regulating new fisheries where long-term characterizations of population dynamics are rarely available. However, an adaptive approach to the fishery requires the incorporation of reproductive data.
KeywordsCoral reef Pseudopterogorgia elisabethae Natural products Population age structure Maximum sustainable yield Compensatory growth
We especially thank Tim Higgs for his willingness to share his detailed records and abundant knowledge of the P. elisabethae fishery. We also thank Marcos Barbeitos, Jaret Bilewitch, J. Jamison, M. Balling, V. Brinkhuis, Lauren Floyd, Andrew Hannes, and numerous volunteer divers for assistance in the field as well as the crew of the R/V F.G. Walton Smith for their friendly assistance during our fieldwork. The research has been supported by the National Science Foundation (OCE 0327129), the New York State Sea Grant Institute (Project R/XG-2), and the National Undersea Research Center at the Caribbean Marine Research Center (CMRC-99-NRHL-01-01C). Funding was provided to Stefano Goffredo by the Marco Polo program of the University of Bologna, the Italian Ministry of Education, University and Research, and the Association of Italian Tour Operators. We also thank the Bahamas Department of Fisheries for permission to conduct research in the Bahamas.
- Beverton RJH, Holt SV (1957) On the dynamics of exploited fish populations. Fishery Investigations, Ministry of Agriculture, Fisheries and Food, London (United Kingdom), Series II 19:1–153Google Scholar
- Bruckner AW (2002) Life-saving products from coral reefs. Issues Sci Techn 18:39–44Google Scholar
- Castanaro J, Lasker HR (2003) Effects of clipping on growth of colonies of the Caribbean gorgonian Pseudopterogorgia elisabethae. Invertebr Biol 122:299–307Google Scholar
- Goffredo S, Chadwick-Furman NE (2003) Comparative demography of mushroom corals (Scleractinia, Fungiidae) at Eilat, northern Red Sea. Mar Biol 142:411–418Google Scholar
- Grigg RW (1976) Fishery management of precious and stony corals in Hawaii. University of Hawaii Sea Grant Program, UNIHI-SEAGRANT-TR–77-03:1–48Google Scholar
- Gutiérrez-Rodríguez C, Lasker HR (2004a) Reproductive biology, development, and planula behaviour in the Caribbean gorgonian Pseudopterogorgia elisabethae. Invertebr Biol 123:54–67Google Scholar
- Pauly D (1984) Fish population dynamics in tropical waters: a manual for use with programmable calculators. International Center for Living Aquatic Resources Management, ManilaGoogle Scholar
- Sparre P, Ursin E, Venema SC (1989) Introduction to tropical fish stock assessment. Food and Agriculture Organization of the United Nations (FAO) Fisheries Technical Paper, RomeGoogle Scholar
- Von Bertalanffy L (1938) A quantitative theory of organic growth (Inquiries on growth laws II). Hum Biol 10:181–213Google Scholar