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

Page 18or harmful fouling organisms are present in the shell to be moved, but not in the destinationpopulation, then this should be taken into account in the risk assessment.Pearl farmers operating in Solomon Islands could conceivably wish to import shell fromother countries. This is currently prohibited under Solomon Islands fishery legislation withoutthe express written consent of the Director of Fisheries and is highly regulated in most othercountries. As a matter of principle, the importation into Solomon Islands of live pearl oystersfrom other countries should not be permitted. Apart from the risk of introducing exoticparasites and diseases, inter-breeding of non-native shell will influence the genetic makeup ofthe local population and possibly compromise any natural advantages that Solomon Islandsshell may have in regard to adaptation to local conditions, pearl colour, growth rates andother characteristics relevant to pearl farming.5.5. Hatchery operationsHatcheries are used to supplement or replace the supply of wild-caught juvenile pearl oysters,as well as to permit selective breeding of pearl oysters with favourable traits for pearl farming(colour, high growth rates, disease resistance, etc.). Hatcheries rely on a small number ofwild-caught broodstock which are made to reproduce in closed tanks or water systems. Thelarvae so produced are initially free-swimming, but settle onto solid substrates after about 20days, and metamorphose into juvenile pearl oysters. Feeding is required in the initial stages,and a pearl oyster hatchery also needs to maintain cultures of live algae for this purpose. Boththe pearl oysters and the algal cultures are susceptible to infection and mass mortality causedby bacterial or other infections, so all aspects of the hatchery operation require high standardsof cleanliness and disinfection.The most significant environmental impacts that hatchery operations may have centre aroundthe uncontrolled disposal of used water and waste products into the surrounding waters. Thismay allow contamination of wild stocks by diseases or infections that may develop in thehatchery, release of non-native algal species or entry of disinfectants and other pollutants intonatural waters. A more subtle impact is that, as hatchery produced larvae join thereproductive population in the wild, they may alter the genetic makeup of the wildpopulation.Pearl oyster hatchery operation requires the culture of algae needed to feed larval andjuvenile pearl oysters. Different species of algae are used at various stages of the pearl oysterlife cycle, and each hatchery operator has his or her own preferences for the types to be used.Algae are usually obtained as sterile monocultures from overseas laboratories, which are usedto inoculate mass cultures within the hatchery. Mass cultures may become infected withbacteria or unwanted algae from time to time, so that they have to be disposed of andreplaced, requiring the hatchery to periodically import new starter cultures . There is theprospect of cultured algae escaping into the natural environment unless waste disposal isproperly managed.The primary environmental management requirement for hatcheries is therefore that all waterdischarge from the facility should be disposed of into an effluent reservoir or sump on land,at least 15m inland from the high tide mark, and well above it. Waste should preferably betreated by chlorination, ultra-violet disinfection or physical filtration to remove pathogensand harmful chemical residues, and should be allowed to settle in the effluent reservoir orsump for several days before draining out. Hatchery waste water should never be dischargeddirectly into the sea, or into rivers, streams or ponds. These measures effectively preventcontamination of the natural environment and wild pearl oyster stocks by the chemical orbiological products of the hatchery.