a1 Centre for Tropical Coastal Management Studies, Department of Marine Sciences and Coastal Management, The University, Newcastle upon Tyne NE1 7RU, England, UK
a2 Marine Research Section, Ministry of Fisheries and Agriculture, Malé, Republic of Maldives.
Export of aquarium-fish from the Maldives began in 1980 and in 1989 almost 54,000 marine fishes, worth approximately US$ 130,000, were exported. The collection of aquarium species is confined to a relatively small area around the capital island, Malé. Estimates of annual exports of 95 species were obtained by examining packing-lists held by Maldivian Customs. In parallel, the population densities of about 70 aquarium-fish species were estimated by visual assessment. Using a number of assumptions, potential (maximum sustainable) yields for 65 of these species — those for which export data were available — were estimated for the area (530 km2) within a 13-km radius (one hour's journey by local boat) of Malé.
For 27 species there were some reasons for concern about the levels of exploitation, although only 12 of these species appeared to be ‘at risk’ in 1986 (the year of highest exploitation). If the assumptions made in estimating potential sustainable yields were valid, these 12 aquarium-fish species were being overexploited or exploited at levels close to maximum sustainable yields. Should the trade expand threefold, a further 12 species are considered to be potentially at risk of overexploitation. Two species of butterflyfish, Chaetodon meyeri and C. triangulum, which feed exclusively on coral polyps and generally die in captivity after a short time, were being exported in significant numbers. Both clownfishes (Amphiprion spp.) and their host sea-anemones were being heavily exploited. Because of the symbiotic relationship between these fishes and their anemone homes, this group may be particularly susceptible to overexploitation.
Damage to branching corals may result from the collection of specimens of Dascyllus aruanus, which shelter within them. With many thousands of individuals of this species being exported each year, this could represent considerable collateral coral damage. Although levels of exploitation of ‘cleaner wrasses’ (Labroides bicolor and L. dimidiatus) appear well below potentially sustainable ones, it is unclear whether the health of reef fishes might locally be adversely affected in heavily exploited areas.
Monitoring and regulation of the aquarium-fish trade is discussed, together with the need for collection of catch statistics by those involved in the trade. The importance of regulation of collection techniques, of standards of facilities, and of satisfactory packaging of fish for export, is stressed. If more accurate estimates of sustainable yields are to be obtained, there needs to be monitoring of populations of key aquarium-fish species in designated collecting areas where exploitation levels are known. Until such estimates become available, the cautious approach adopted in the Maldives to estimate yields and set species-based quotas will, it is hoped, prevent local overexploitation.