Stimulating investment in pearl farming in ... - World Fish Center

Suitability of Habitats for Growth of Black-Lip and Silver-Lip Pearl Oysters Final, June 2008SUMMARYBackgroundThe European Union has funded a project entitled ‘Stimulating investment in pearl farmingin the Solomon Islands’. The objective of this project is to provide offshore pearl companieswith sufficient information to determine the potential for long-term investment in pearlfarming in the Solomon Islands. The World Fish Centre sub-contracted The Ecology Lab Ptyto prepare a report comparing coral reef lagoons and habitats suitable for growing black-lip(Pinctada margaritifera) and white-lip pearl oysters (Pinctada maxima) in the Solomon Islandswith several other locations in the Pacific, for this project. The conclusions drawn about thesuitability of coral reef habitats in these regions are based on existing information about theenvironmental needs of each species, the environmental conditions prevailing at farmlocations, the different types of coral reef and lagoon habitats in the specified regions andtheir prevailing environmental conditions and the influence of the natural environment onthe various culture phases.Environmental needs of pearl oystersThe physiology, survival and productivity of bivalves is known to vary with temperature,salinity, type of substratum, depth of the water column, silt load, water currents, primaryproductivity and pollution. The response of black-lip and silver-lip pearl oysters tofluctuations in these environmental factors, however, is poorly documented. Experimentalstudies in Australian waters indicate that adult silver-lip pearl oysters are less tolerant oflower temperatures but more tolerant of high temperatures and are capable of coping with awider range of food concentrations and more turbid conditions than their black-lipcounterparts. This implies that they may be cultured under a greater variety ofenvironmental conditions. It should, however, be noted that spat, juveniles and adults mayexhibit different responses to these environmental factors and that the physiologicalresponses of these species may vary across their latitudinal range. The review also suggeststhat little is known about the environmental conditions under which natural populations ofblack-lip and silver-lip pearl oysters grow in the South Pacific region. Most of theinformation obtained about the environmental needs of pearl oysters came from Australia orFrench Polynesia.Environmental conditions at existing pearl farmsThe most productive black pearl farms are located in atoll lagoons in French Polynesia andthe Cook Islands. Considerable information is available about the environmental conditionsin their vicinity of some of these farms. These lagoons differ markedly in total surface area,depth and degree of exchange with the ocean. The feasibility of establishing farms in othercoral reef habitats has been investigated in Fiji, the Solomon Islands and Vanuatu, andcommercial farms have since been established in Fiji and Australia. The farms in Australiautilize juvenile pearl oysters from hatcheries, whereas those elsewhere are based on wildspat or stock. Little information is available about the environmental conditions at thesefarms. The paucity of information on environmental conditions prevailing in SolomonIslands relative to Cook Islands and French Polynesia precludes an assessment of whetherconditions for pearl farming would be comparable.Silver-lip pearl oysters are currently being farmed in the northern part of Western Australia,Northern Territory, Queensland, Torres Strait Islands and in a few areas of Papua NewGuinea. The silver pearl industries in West Australia and Queensland are based primarilyon the collection of wild oysters and hatchery-derived spat, respectively. The industry inThe Ecology Lab Pty Ltd – Marine and Freshwater StudiesPage i