Inshore Fisheries Research Project Country Assignment Report REPORT OF A SURVEY OF THE PEARL OYSTER RESOURCES AT NUKELAELAE ATOLL, TUVALU South Pacific Commission Noumea, New Caledonia REPORT OF A SURVEY OF PEARL OYSTER RESOURCES AT NUKULAELAE ATOLL, TUVALU April 1990 Draft G. L. Preston South Pacific Commission M. T. Gentle Tuvalu Fisheries Department M. Kamatie Kiribati Fisheries Department M. Naseli Tuvalu Fisheries Department SUMMARY ACKNOWLEDGEMENTS 1. INTRODUCTION 1.1 Aims 1.2 Background Information 2. ACTIVITIES 2.1 Logistics 2.2 Survey methodology 3. RESULTS 3.1 Information from island residents 3.2 Direct pearl oyster sampling 3.3 Other observations 4. DISCUSSION 4.1 Pearl oyster culture prospects in Nukulaelae 4.2 Future work APPENDICES 1. Field station descriptions 2. Spat collector designs (to be completed) SUMMARY A survey of pearl oyster stocks was carried out in Nukulaelae in April 1990, to determine the potential for pearl oyster culture in the lagoon. The survey involved intensive searching for pearl oysters, by free diving or SCUBA diving, at 19 sites in and around the lagoon. The survey was carried out by a 4-man diving team, assisted by island residents with local experience of pearl oyster collection. Good coverage of the different habitat types in the lagoon, and a comprehensive distribution of sampling effort, was achieved. Consultations were also held with local residents to gather anecdotal information on the abundance and expoitation history of the resource. Pearl oyster stocks were determined to be low, especially relative to other countries where pearl oysters have been commercially exploited or cultured. Only four live specimens were found during the field work, although it was possible to examine other live and dead shell that had already been collected by island residents. Present stock levels are not adequate to support the establishment of farming activities on even a very small scale. There is no evidence that stocks were ever vastly more abundant than they are now, or that they have been greatly reduced by human collection activity. Despite the low abundance of pearl oysters, Nukulaelae lagoon appears to present some localised areas of suitable pearl oyster habitat. The fact that these are populated by other bivalve species suggests that physical, chemical or biological conditions in the lagoon are limiting pearl oyster population growth. It is speculated that the limitation may be acting at an early point in the pearl oyster life cycle, since the few adults taken from the lagoon during the survey, as well as shells belonging to private individuals, appeared to demonstrate good growth and to reach relatively large sizes. Further research is required to determine whether pearl oyster population growth could be promoted by enhancing larval settlement and growth using spat collectors and juvenile husbandry methods. The constraints of initiating such a project on Nukulaelae are discussed, and an alternative approach suggested. This involves initial deployment of spat collectors in Funafuti for research purposes, and the gradual extension of this research to Nukulaelae and perhaps other Tuvaluan atolls depending on results, logistics, and institutional arrangements. ACKNOWLEDGEMENTS Our thanks go to the people of Nukulaelae for their warm welcome and hospitality during our visit to the island. President Tinilau Lomi and other members of the island council were enthusiastic about the survey and encouraged Nukulaelae residents to assist us and share their knowledge with us. Lenese Telava and Lemoe Kailu were especially ready to do so. Our boatmen Nafatele Filemoni, Maiau Nafatele, and Vaiola Telupe gave up public holidays and worked unsocial hours to convey us safely to and from our dive sites. Island Executive Officer Teleke Pelete effectively organised all local support for, and administrative aspects of, our work. Thanks also to Loto Pasifika and the crew of the Manaui for getting us to Nukulaelae and back again efficiently and safely, and for entertaining us on the way. 1. INTRODUCTION 1.1 Aims The culture of pearl oysters has become an important industry in French Polynesia and the Cook Islands, where it takes place in outlying atolls. Pearl oysters collected from the wild, either as adults or as juveniles, are grown for their shell or, more importantly, for the production of cultured pearls or half-pearls generated by artificial seeding. Several characteristics of pearl oyster farming - relatively low set-up cost, relatively low technology, limited infrastructure requirements, and a high-value, non-perishable product - make it a potentially appropriate income earning activity for rural or outer-island people. As a result, the governments of other Pacific Island countries, including the Marshall Islands and Kiribati, are becoming increasingly interested in investigating the potential of pearl oyster culture as an economic activity. This interest is shared by the government of Tuvalu, which, in late 1989, requested SPC assistance in carrying out surveys of wild pearl oyster stocks in selected Tuvaluan atolls and, where appropriate, in promoting the development of local pearl oyster culture activities. Based on anecdotal information, the atolls thought to have potentially adequate pearl oyster stocks for pearl oyster culture were Nukulaelae, Funafuti, and Nukufetau, in that order. The first survey, of Nukulaelae atoll, was carried out by the Tuvalu Fisheries Division, with financial and technical support from the SPC Inshore Fisheries Research Project, in April 1990. The survey team involved personnel from Tuvalu Fisheries Division (M. T. Gentle and M. Naseli), the South Pacific Commission (G. L. Preston), and the Kiribati Fisheries Division (M. Kamatie). The participation of the Kiribati officer was arranged at the request of the Kiribati government as a hands-on training exercise, in support of further survey work planned for Kiribati. This report summarises the results of the survey and discusses possible pearl oyster culture development options for Nukulaelae and other locations in Tuvalu. 1.2 Background information Nukulaelae (figure 1) is a kidney-shaped closed atoll approximately 10.5 km long by 4.5 km wide. Vegetated islands or islets lie along much of the atoll reef. At present only two of these are permanently inhabited: the main village of Fangaua, which has a population of about 300 people, is located on the island of the same name in the north-western part of the atoll; and there is a single, new, household at the northern end of Tumiloto island. Access to Fangaua from the sea is by a small man-made passage, blasted in the early 1980's, through the barrier reef. Small skiffs or lighters can pass when through when weather and tidal conditions permit, at risk of being swamped by breakers. Only small, shallow-draft vessels can enter the lagoon from outside, or vice versa. Insert map of Nukulaelae Communications between Nukulaelae and other Tuvalu islands are limited. The government shipping vessel Nivaga II calls in from time to time, typically once every 6 weeks to two months, carrying supplies and mail. Voice communications with other islands, and with ships at sea, can be made by SSB radio telephone. Nukulaelae inhabitants rely mainly on local agriculture and fishing for the majority of their foodstuffs. Locally raised products include coconuts, various kinds of taro, sweet potatoes, chickens, ducks and pigs. Fishing is mainly tuna trolling outside the reef, although lagoon species are also captured by spear, hook and line, and gill net. Some imported staples (rice, flour, sugar, etc) are available via the Fusi (Tuvalu Cooperative Society) store, as are other household requisites such as tea, soap, tobacco, etc. Economic activity is limited, and is mainly related to work performed by or on behalf of the island council, which is the major employer and administers projects financed from public or aid funds. Private economic activity is extremely limited: there is one small private shop, occasional sales of fish or agricultural produce within the island community, and production of small quantities of handicrafts for export. 2. ACTIVITIES 2.1 Logistics The survey was carried out between 9 and 25 April 1990. The period Thursday April 12 to Saturday April 20 was spent carrying out field work on Nukulaelae. The remaining time was spent either in Funafuti or in transit. Overseas members of the team arrived in Funafuti on April 9 (Preston) from Suva, and April 10 (Kamatie) from Tarawa, respectively. Preparation of equipment, and survey planning using available navigational and bathymetric charts, a shakedown dive for three members of the survey team, and loading of equipment and personnel on to the government ship Manaui, an approximately 15 m Japanese-built fisheries extension vessel, occupied Monday 9 to Wednesday 11 April. Equipment used by the team included: a portable petrol driven air compressor; basic free-diving equipment (masks, snorkels, fins); four sets of SCUBA diving equipment (tanks, regulators with contents gauges, and buoyancy compensators); surface navigation instruments (two hand-bearing compasses, optical range-finder, hand-held depth sounder); underwater navigation, sampling and recording equipment (submersible watches, compasses, depth gauges, 50 m buoyed and weighted transect lines, writing slates, waterproof paper and pencils); and marine and bathymetric charts. Additional equipment taken to Nukulaelae but not ultimately used on the island included a 12- volt digital/ paper chart echo-sounder, as well as power supplies for this item (12v truck battery, battery charger, and portable diesel-powered 24/220v electrical generator). The Manaui travelled to Nukulaelae on the night of 11 April. Using the Manaui's skiff, as well as two local dinghies, the equipment was unloaded on the morning of April 12 into a small rest house assigned to the team by the island council. After the team was installed and equipment had been set up, a meeting was held with the island council and the survey aims discussed at length with island elders. Field survey work commenced on the afternoon of April 12 and continued during 7 of the next 8 days.