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

Abundance, Size Structure and Quality of Silver-lip Pearl Oysters in the Solomon Islands Final, June 2008• Collaborate with WorldFish staff to develop sampling designs to obtain precise andaccurate estimates of the density and size structure of silver-lip pearl oysters at up to10 sites throughout Solomon Islands;• Participate in underwater surveys at selected sites to obtain estimates of abundance,and sub-sample the oysters there to estimate size structure and nacre colour;• Analyse data from the UVC and video surveys, and the sub-sampled oysters, at allsites to calculate:1) the abundance of silver-lip pearl oyster stocks at each site, and across all sites,2) the number of sustainable quotas of silver-lip pearl oysters that could beallocated for pearl farming within and across all sites, and3) the proportion of oysters at each site with the preferred silver nacre.• Prepare a report on the abundance, size structure and variation in nacre colour ofsilver-lip pearl oysters in Solomon Islands, and the recommended number ofsustainable fishing quotas that could be allocated for pearl farming based on datacollected at all sites; and• Prepare a manuscript for the Journal of Shellfish Research on the abundance, sizestructure and variation in nacre colour of silver-lip pearl oysters in Solomon Islandsbased on the UVC and video data, and sub-sampling, at all sites.This report focuses on the abundance, size structure and variation in nacre colour of silverlippearl oysters in Solomon Islands, and the recommended number of sustainable fishingquotas that could be allocated for pearl farming based on data collected at all sites.1.2 Existing Information1.2.1 History of ExploitationNatural pearl oyster populations in Solomon Islands have been exploited for at least twocenturies (Colgan 1993). Three species: silver-lip (Pinctada maxima), black-lip (Pinctadamargaritifera) and brown-lip pearl oysters (Pteria penguin) were exploited commercially forthe nacre or mother–of–pearl (MOP) in their shells. The MOP was initially exportedunprocessed to Japan, however, in 1990 button factories were established in Honiara(Richards et al. 1994).Small-scale commercial exploitation of gold-lip pearl oyster began in 1916 and was carriedout by Japanese hard hat divers based at Aratoba Island near Waghina until 1922 (Gauld1975 in Colgan 1993). In 1968, the fishery at Aratoba Island was re-opened by the Palmerfamily based on Gizo. Fishing was done by hookah divers and Hamilton Channel,Waghina, Kia, Rob Roy Channel and Popu Passage were the major areas fished. A largesilver-lip pearl oyster bed was also found at Ngella, but was decimated soon after by adisease outbreak (Gauld 1975 in Colgan 1993). Silver-lip pearl oysters were also found inMarau Sound. Attempts were also made to collect spat, but only black-lip pearl spat settledout.At the peak of its operation, the Solomon Islands Mother of Pearl Company formed bythe Palmer family employed 22 divers. The fishery was terminated in 1972 because ofdeclining stocks resulting from overfishing, increased operational costs and a decline inMOP prices on world markets. In 1987, a pearl fishery employing divers of I-Kiribati origincommenced operations at Waghina (Colgan 1993). In 1994, the export of wild-caught blacklipand silver-lip pearl oysters was banned due to overexploitation (Kile 2000). In theThe Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 2