SURVEY OF Pinctada maxima, GOLD-LIP PEARL OYSTERS, IN THE WAGINA REGION, SOLOMON ISLANDS by Kathy Colgan Bureau of Rural Resources, Canberra, Australia FFA Report #93/46 CONTENTS SUMMARY AND RECOMMENDATIONS ..............................................................2 INTRODUCTION........................................................................................................6 Past surveys for P.maxima ................................................................................6 Production.........................................................................................................7 Survey objectives..............................................................................................8 HISTORY OF PEARL OYSTER EXPLOITATION IN SOLOMON ISLANDS.......9 SURVEY DESIGN ......................................................................................................10 Sample areas.....................................................................................................10 Sampling Methods............................................................................................10 RESULTS.....................................................................................................................12 DISCUSSION ..............................................................................................................13 (i) Distribution and relative density of gold-lip oyster stocks in the Wagina area. .............................................................................................................13 (ii) The impact of past fishing activities for this shell......................................14 (iii) Assess the potential for the development of a pearl culture industry in Solomon Islands. ........................................................................................17 Collection of shell for MOP......................................................21 Pearl culture ..............................................................................21 (iv) Experience provided to Solomon Island fisheries officers........................22 (v) Utilisation of expertise from other Pacific Island countries .......................23 FISHERIES MANAGEMENT RECOMMENDATIONS...........................................23 Size limits .........................................................................................................23 Conservation measures.....................................................................................23 Public education programme using video ........................................................24 Recommendations for Wagina .........................................................................24 ACKNOWLEDGMENTS............................................................................................25 REFERENCES.............................................................................................................26 Appendix A Survey Participants..................................................................................27 Appendix B Itinerary for K. Colgan ............................................................................28 Appendix C.......................................................................................................Dive sites, benthic fauna, sediment composition and shell collected. ......................29 i SUMMARY AND RECOMMENDATIONS 1. INTRODUCTION A one week diving survey of the pearl oyster resources of the Wagina area was carried out during December 1990 by the officers of the Solomon Islands Fisheries Division, representatives from the pearling industry and Ministry of Marine Resources of Cook Islands and a consultant from the Bureau of Rural Resources (BRR), Australia. 2. LOW ABUNDANCE The survey showed that there were few pearl oysters in the Wagina area above the depth of 50m. There is some evidence that shell is being fished at 70m at present but the diving methods being used to collect the shell are very dangerous. Anecdotal information suggests that Pinctada maxima was once plentiful in this area but the shell has been overfished in recent years. 3. COMMERCIAL FISHING POTENTIAL Based on survey results, there is NO potential for commercial fishing in the Wagina area. Immediate steps should be taken to preserve the remaining stock of P. maxima. Two dives at Kia revealed the presence of P. maxima and this area should be further investigated. 4. POTENTIAL FOR PEARL CULTURE At present stock levels, there is no potential for a pearl culture venture in the Wagina area. However, should stock be re-established in the area then this question could be looked at again in future years. 5. LONG TERM DEVELOPMENT OF THE PEARL INDUSTRY IN THE SOLOMON ISLANDS Though current information is scanty, there may be reasonable stocks of both gold-lip (P. maxima) and black-lip (P. margaritifera) pearl oyster, in Solomon Islands. It is recommended that: i. a detailed research program be undertaken to document all published and unpublished material relating to stocks of P. maxima and P. margaritifera in the Solomon Islands. The author found that there were people in the community that had much valuable information to give concerning the past status of stocks. In some cases, old records of fishing activities have been kept. This information could be most valuable to Solomon Islands' fisheries officers but it would require some effort to gather the information. ii. all export statistics related to pearl shell be collected, particularly the place of origin of the shell and when the shell was fished. iii. when all information has been collected, areas which look promising should be visited and field surveys be undertaken to determine the stock status. iv. after the research and field surveys, a decision could then be taken regarding the type of pearl industry that would suit the local conditions. It may be better for example to start with an industry based on Mother-Of-Pearl (MOP) and once that is established, investigate the possibility of a pearl culture venture. ii INTRODUCTION Solomon Islands is situated in the southwestern Pacific Ocean, the capital Honiara being about 1,600 km east of Port Moresby and 2,575km north-east of Sydney (Fig. 1). It consists of a double chain of six large islands (Choiseul, Santa Isabel, New Georgia, Malaita, Guadalcanal, San Cristobal) and many smaller ones (Fig. 2). The country has a land area of approximately 27,556 sq. km and is spread over 600,000 sq. km of ocean (White, 1991). The survey area was north- west of Santa Isabel, around Wagina Island (Fig. 3). Pinctada maxima, the gold or silver-lip pearl oyster, has been collected on a small scale in Solomon Islands for at least two centuries. Shell is now taken in Solomon Islands for Mother-Of- Pearl (MOP) but there is increasing interest in assessing the potential of a pearl culture industry in Solomon Islands. Over the past 15 years, the Solomon Islands Government has received many expressions of interest from foreign investors interested in participating in pearl culture programmes. However, uncertainty about the availability of suitable live shell resources has constrained active development. Past surveys for P. maxima Since 1988, there have been two surveys to the Santa Isabel region to assess the potential P. maxima resource. Solomon Taiyo Ltd. conducted a survey around west Isabel in 1988, (Nichols 1988). In two weeks, using three divers, forty-nine P. maxima were found. Most of the shells found during the survey came from Kia and Port Praslin Passage (Fig. 3). Measurements of the shells found during the survey showed that mostly large shells were present, which are not considered suitable for farming (Fig. 4). Generally shells less than 200mm is preferred for pearl culture. It was concluded that there were not enough shells to support commercial operations in the north-west Isabel region. Figure 4 Dorso-ventral measurements of gold-lip shells taken during 1988 Solomon Taiyo survey 16 14 n = 49 12 10 8 6 Number of shells 4 2 0 100 120 140 160 180 200 220 240 260 280 300 Dorso-ventral measurement (mm) During the survey, the diving team was unable to dive in certain areas due to disputes with reef owners, who did not allow access to particular locations. Therefore the area was not fully surveyed. From the data which was able to be collected, it was concluded that P. maxima was scarce in the north-west Isabel region (Nichols,1988). As a result of the Solomon Taiyo survey, a further survey of the Kia area was carried out in 1990. A total of twenty-two dives were carried out over six days by two divers, (Batty and Kile, 1990). Forty-six P. maxima were found, with most shells coming from the Ghehughaha and Bahana passage near Barora Ite Is. (Fig. 3). As was the case in previous surveys, large shells were found which would not be suitable for pearl culture. Production Between 1982 and 1988, less than 10mt of P. maxima a year was exported from Solomon Islands but in 1989 production increased to 22mt (Fig. 5). Figure 5 Gold-lip exports from Solomon Islands, 1981-1989 (Source: Solomon Islands Fisheries Division). 25 t 20 15 10 5 Weight of gold-lip in m 0 1981 1982 1983 1984 1985 1986 1987 1988 1989 Year Export statistics obtained from traders in Honiara, suggest that much of the pearl shell being exported is coming from the Wagina area (Fig. 6). These figures do not include exports from Gizo and Munda and so do not give a complete picture of where gold-lip has been taken from. There was no information available on the