Inshore Fisheries Research Project Country Assignment Report

REPORT OF A SURVEY OF THE PEARL OYSTER RESOURCES AT NUKELAELAE ATOLL,

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 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 , 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 , 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. Diving was prohibited on Easter Sunday (April 15), as well as on the mornings of Good Friday (April 13) and Easter Monday (April 16), due to local religious convention. All field work was carried out from a small (appx 9m) outboard-powered catamaran (figure ) owned by, and chartered from, the island council. The charter fee included provision of a boatman and fuel, except on two occasions where private arrangements were made for these aspects of the charter. Insert photograph

of catamaran

A second meeting with the island council was held on the morning of Saturday April 21, the last day the team spent on the island. The survey results, and possible pearl oyster culture development approaches for Nukulaelae, were discussed in detail with the council members. The rest of the day was spent in cleaning and packing equipment and loading it aboard the Manaui for the trip back to Funafuti. Manaui departed Nukulaelae in mid-afternoon, arriving in Funafuti after midnight. The vessel was unloaded on Sunday April 22.

A draft report of the survey was prepared on Monday April 23 and Tuesday April 24. Copies were delivered to the Prime Minister, the Acting Chief Fisheries Officer, the General Manager of the National Fishing Company of Tuvalu, and other Tuvalu Government officials, on Wednesday April 25. The report was finalised on after their comments had been accounted for.

Overseas members of the team (Preston and Maruia) departed on Wednesday April 25.

2.2 Survey methodology

The two main aspects of the field survey work were:

interviews, consultation and discussion with island residents, to take advantage of local knowledge and experience in locating pearl oysters, and to quantify past levels of pearl oyster abundance and exploitation; and

estimation of levels of pearl oyster abundance by direct observation and sampling. Interviews and discussions were held during two formal meetings with the island council, and then, informally, on numerous occasions with single individuals or in small groups. On most diving trips one or more local residents also accompanied the team during field survey work, either to assist in locating likely pearl oyster-bearing areas, or simply because of interest in the survey activities. Local residents were extremely supportive of all aspects of the survey and readily volunteered information and suggestions. Direct observation was carried out according to a routine in which one or two field stations were sampled by diving each morning, and again each afternoon. Sampling sites were initially selected in consultation with local residents, the aim being to locate areas of known pearl oyster abundance. Subsequently, once the team members were more familiar with the geography of the lagoon, sites were selected according to the following criteria: the site's degree of promise as favourable pearl oyster habitat; desire to achieve good overall coverage of the lagoon; and desire to achieve coverage of a range of habitat types.

Once a site had been selected, dives were carried out to determine the presence or absence of pearl oysters. Diving was carried out with or without SCUBA gear depending on the depth, type of substrate, and visibility. When using SCUBA gear, pairs of divers would follow a pre- determined compass course along the bottom, searching for pearl oysters in a band either side of the line of swim. When free diving, divers tended to operate singly and to swim away from each other on a general compass heading, searching more widely from side to side. In both cases, searching for pearl oysters was carried out intensively. Particular care was taken to inspect heads of coral or calcareous algae very thoroughly, and to check inside cracks and crevices at close range, since these were likely hiding places for pearl oysters. At all stations where there was bottom at less than 5 m, one or more island residents would independently search for shell by free-diving, sometimes in a competitive attempt to outdo the survey team. Searching practices were therefore felt to be comprehensive and effective.

Apart from one practice deployment of the transect line on the first dive, no quantitative density sampling was attempted, since pearl oyster densities were never high enough to justify it.

Weather conditions were generally favourable during the survey period. Prevailing winds were from the south-east, and for most of the period averaged between 5 and 15 knots. A south- easterly swell prevented diving over the eastern reef-edge but this was not a serious impediment to the field work. Rain squalls and associated stronger winds occasionally passed over the lagoon but these were not frequent or violent enough to interfere with field activities. The main constraint on field work was poor underwater visibility. The persistent breeze and associated wave activity maintained the water in a turbid condition in some parts of the lagoon, and heavy sedimentation restricted visibility in deeper areas. Visibility seldom exceeded 15m in the upper levels and dropped as low as 2m on the lagoon floor or in disturbed areas (mainly close to shore). The principal result of poor visibility was to limit the area that could effectively be surveyed by a pair of divers, since for safety reasons the divers remained within visual contact of each other.

In between field sampling visits, the team returned to the rest house to eat, fill SCUBA tanks, write up field notes, and consult with local residents about results and future sampling sites.

3. RESULTS

3.1 Information from island residents

Residents of Nukulaelae agree that pearl shell are common and easy to find in Nukulaelae relative to other Tuvaluan islands. In support of this contention, several individuals described occasions on which they had found three, five, or, in one case, ten, shell in a single day. These numbers were considered high by local people. In fact, they are low by the standards of other Pacific Island locations where the returns on pearl oyster diving may be considerably higher. Pearl oysters are normally found while spear fishing or carrying out other activities on the lagoon. In most cases, island residents do not make trips expressly to find pearl oysters, although this doubtless happens from time to time. Some fishermen have spotted shell from their boats while fishing in calm weather, and subsequently dived to collect them. It is said that on a calm day the shell can be seen because it causes a "sort of rainbow" on the water surface. It is also said that a good time to look for pearl oysters is in calm weather after a period of westerly winds. The westerly is thought to disturb the sand in such a way as to cause the pearl oysters to be more exposed and easy to find. The main use of pearl oysters is in making fishing lures for tuna poling. This method was common throughout Tuvalu some years ago but since the advent of outboard motors is in decline, having been largely replaced by trolling. In the past, Nukulaelae pearl oysters were in demand throughout the islands of Tuvalu, as well as in Kiribati, and unknown quantities of shell were harvested to supply this market. All accounts suggest that this trade was small, with the numbers of shell being sold at any one time being in single figures, or at the most, tens. There does not appear to have been any large-scale harvesting for export to button makers and other mother-of-pearl users overseas. Because of their traditional value and high quality, it has been a common practice for fishermen finding small pearl oysters to transplant them to safe, accessible places for ongrowing to a suitable size for lure manufacture. This practice still persists in a small way: figure shows a pearl oyster which has been transplanted to an artificial shelter for safe ongrowing.

Insert photograph showing

pearl ongrowing site

Island residents recognise at least three types of pearl oyster, which are not distinguishable from each other externally but are categorised by internal shell colour, as follows: laumilo, which has a golden or yellow coloration; ngu, which is white, and relatively uncommon; and fululupe, which is grey or bluish. All are presumed to be colour variations of the black-lip pearl oyster, Pinctada margaritifera, the species native to much of Polynesia. The other Pacific island species, Pinctada maxima, the gold-lip pearl oyster, has been introduced to some Polynesian locations from the western Pacific, but there is no record of its having been brought to Nukulaelae or other parts of Tuvalu.

Historically, fululupe were mainly found in the northern half of the lagoon (Avafoa) while laumilo were characteristic of the southern part (Fakalava). In recent times, this clear separation has disappeared and both types are now equally dispersed throughout the lagoon.

Laumilo is the pearl shell for which Nukulaelae is famous, and has traditionally been sought after by tuna fishermen from other Tuavaluan islands because of its colour, which is effective for fishing under certain conditions. Unlike fululupe, it is not thought to be present in other Tuvaluan islands. Laumilo features in traditional fishing songs and stories in Nukulaelae: the same is true of fululupe in Funafutui.

3.2 Direct pearl oyster sampling

Searches for pearl shell were carried out at a total of 19 stations, as shown in figure . Of these stations, 4 (#'s 2, 7, 14 and 18) were searched exclusively by free diving, 4 (#'s 1, 3, 4, and 15) by a mixture of free diving and SCUBA diving, and the remaining 11 exclusively by SCUBA diving. A description of each station, and other relevant information, is given in appendix 1.

Insert figure showing sampling sites

Stations 10 and 16 were sloping mud or fine sand bottom with little or no coral cover and with high levels of fine sediment, both suspended in the water column, and deposited on the bottom. Station 18 was immediately behind the outer reef on the windward side of the island, and had a substrate of vigorous live coral mixed with patches of coarse sand. Station 19 was on the outer reef slope on the leeward side of the island, where the substrate consisted of extensive dense beds of living stagshorn corals down to 10m, and, beyond that depth, large expanses of mainly dead stagshorn corals covered with encrusting calcareous algae. None of these stations appeared to be good pearl oyster habitat, and no pearl oysters were found in these locations.

8 3 stations (#'s 2, 7 and 14) were areas of shallow sand dotted with heads of coral or coralline algae, and contiguous with the reef back. 8 stations (#'s 6, 8, 9, 11, 12, 13, 15 and 17) were shallow patches which rose from relatively deep water within the lagoon, and whose tops and upper sides generally consisted of fairly coarse sand with frequent outcrops of massive and stagshorn corals. 4 stations (#'s 1, 3, 4, and 5) were intermediate between these two types. All these stations, especially those on shallow patches within the lagoon, appeared to be fair or good pearl oyster habitat.

Despite their apparent promise, however, only four pearl oysters were found, three at station 11 and one at station 12, both shallow patches in the lagoon. All specimens were Pinctada margaritifera. Those found at station 11 measured 23,12, and 1 cm (dorso-ventral measurement, DVM) respectively. The smallest individual was found attached to the largest shell. The shell found at station 12 measured 4 cm DVM. All specimens were found in depths of between 8 and 10 m. The disturbed growth rings of the 12 cm shell suggested attack by a predator at an earlier stage in the animals life (figure ).

Insert photograph showing pearl oyster specimens

Two dead shells, one relatively fresh and in good condition, and one old and very degraded, were also found at stations 1 and 5 respectively. 3.3 Other observations

Numerous areas of Nukulaelae lagoon appear to provide suitable habitat for adult pearl oysters. However, these areas are invariably colonised not by pearl oysters but by very large numbers of either thorny oysters (family Spondylidae), jewel-box clams (Chama spp), or both. Many were extremely large (25 cm or more in diameter), while most were approximately fist-sized. While no quantitative measurements were made, densities in some areas were estimated at over 30 of these bivalves per square metre.

Most of the floor of Nukulaelae lagoon is covered with a uniform fine sediment which is also present in suspension in the water, obscuring visibility and choking bivalves, algae or coral which are attempting grow in the deeper areas. The slopes of all the shallow patches investigated by the survey team descend to a basal plain of fine sediment which is bare of surface life. Most of the lagoon floor is covered by conical mounds ("sand volcanoes") created by burrowing animals, possibly dendrochirotid holuthurians.

Because of persistent winds during the survey period, the bottom sediments may have been more disturbed than usual. Nevertheless, sedimentation is undoubtedly very heavy, especially in the lower reaches of the lagoon, and it seems unlikely that the lagoon floor, apart from those shallow patches that rise close to the surface, could ever provide a suitable habitat for pearl oysters or any other type of epibenthic bivalve. 4 DISCUSSION 4.1 Pearl oyster culture prospects in Nukulaelae The results of the survey make it clear that the density of pearl oysters in Nukulaelae is extremely low relative to locations in many other countries. The low densities encountered precluded any attempt to make a realistic estimate of abundance or standing stock, but it is certainly too low to enable the stocking of even a very small pearl oyster farm.

Anecdotal information suggests that, in living memory, although the abundance of pearl oysters may have been higher in Nukulaelae than in other Tuvaluan atolls, it has still been relatively low in absolute terms. The fact that fishermen did - and still - protectively rear small pearl oysters until they reached a usable size reinforces the view that the animals were scarce enough to warrant this extra care. Given that harvest levels appear to have been modest, and there does not seem to have been any period of very intense collection (as has happened in many other Pacific Islands where pearl oysters were previously very abundant), it would appear that the low densities are a natural feature of the lagoon and not principally a result of human harvesting activity.

Despite the low densities, there appear to be numerous, if somewhat localised, areas of apparently suitable pearl oyster habitat. The fact that these are not colonised by pearl oysters suggests that some deleterious influence is at work to prevent the settlement, survival, growth or reproduction of the animals. This may be associated with: the heavy sediment levels observed in the lagoon; the high densities of thorny oysters and jewel-box clams, which may compete with pearl oysters during some part of their life cycle; or to other so far undocumented physical, chemical or biological features of the lagoon.

Pearl oysters reproduce by producing large numbers of microscopic eggs which, after fertilisation, spend a period of time as free-swimming plankton before settling onto suitable bottom and metamorphosing to become juveniles. The reproductive success of a pearl oyster population depends on the animals spawning synchronously, and on the meeting of adequate numbers of freshly released eggs and sperm. This in turn requires a certain minimum concentration of adults in reasonably close proximity to each other, a situation which does not appear to exist in Nukulaelae.

Subsequently, in order for population growth to take place, the planktonic larvae need to find a suitable substrate on which to settle, and where a reasonable proportion can find adequate food supplies, and shelter from predators to grow to adulthood. It is not known whether adequate areas of suitable habitat for settling pearl oysters exist in Nukulaelae, or what the level of predation, parasitism and disease may be among larvae or juveniles.

If the pearl oyster population in Nukulaelae is being limited by inadequate reproductive success of the existing very small population, or restricted spat (larval or juvenile) survival, it may be possible to mitigate this to some degree by deploying spat collectors. These are simple structures, typically made at low cost from rope and plastic sheeting, which provide a suitable habitat for larval settlement and allow the husbanding of newly settled juveniles through the early stages of life by a combination of thinning, cleaning, and transferral to suitable grow-out conditions. If the collectors operate successfully, developing pearl shell can then be grown on in a small-scale pilot farming activity, or returned to apparently suitable adult habitat and monitored for survival and growth in the wild. In either case positive feedback should occur, with a gradual increase in the adult population ultimately leading to increasing spatfalls, thus accelerating the establishment of a larger standing stock, whether under culture or in the wild. 10 If the limitation is acting on some other point in the life cycle, particularly on adult survival and growth, it is difficult to see what could be done to enhance the natural population. However, this situation seems less likely, given that both the live and dead pearl shell observed seemed to exhibit reasonably vigorous growth rings, and that adult shell, some quite large, have been taken from the lagoon in small numbers for many years.

The island council and many residents of Nukulaelae were disappointed to learn that existing pearl oyster stocks in their lagoon would not, as anticipated, support culture activities. They expressed a wish that the Fisheries Division continue to investigate ways in which pearl oyster culture might nevertheless be instigated in Nukulaelae. It was made clear that any such initiatives by the Fisheries Division would have to be considered strictly as research that may or may not have a successful outcome, and that a long-term perspective would need to be adopted.

4.2 Future work A natural follow-up activity to the survey would be to deploy a series of simple, low-cost spat collectors in Nukulaelae lagoon in order to allow monitoring of juvenile settlement and growth in the lagoon. Only when an assessment of potential spatfalls has been made can Nukulaelae's true potential for long-term development of pearl oyster culture be assessed. Suitable spat collector designs and material specifications are given in appendix 2.

However, logistical arrangements may make such a programme difficult to carry out on Nukulaelae. Spat collectors would need to be constructed, deployed, and then cleaned and maintained regularly and juvenile settlement monitored. This would require either a locally based, and appropriately trained or qualified, individual to look after the project (possibly on a part-time basis) or frequent visits by a staff member from Funafuti. Present organisational arrangements appear to make each of these alternatives difficult.

As a stepping stone, it may be worth deploying several spat collectors in Funafuti atoll where they can be maintained and monitored relatively easily by Fisheries Division staff. An advantage to this approach is that spat collector deployment in Funafuti could be linked to ongoing or planned activities to establish giant clam growout sites and seaweed farming operations. Such a simple research project would provide potentially valuable information on pearl oyster settlement in Funafuti at relatively little cost and effort. There is presently no reason to suppose that the settlement rate that might be achieved in Funafuti is likely to be worse than at any other island in the group.

This approach would also present an opportunity to provide training in spat collector maintenance, deployment, and eventually, juvenile pearl oyster monitoring and care, for one or more residents of Nukulaelae, if in the interim the financial means are found to support a research project based on the island. If warranted, such a programme could ultimately be extended to other islands in the long term.

This suggested approach should be viewed first and foremost as a research project intended to clarify certain aspects of pearl oyster population dynamics in Funafuti and, ultimately, other selected Tuvaluan atolls. Acquiring information on pearl oyster spatfalls and juvenile growth and survival is a prerequisite before culture activities can be envisaged, but does not guarantee that culture will ever prove to be feasible. As a research project, it needs to be assigned appropriate priority alongside other fisheries projects that may have more definite or immediate potential benefits. If the Tuvalu government is not prepared to assign at least a medium priority to this activity for at least five years, then it should not be commenced. However, given the low costs, low effort, and potentially significant gains involved, research of this nature seems an appropriate activity for the Tuvalu Fisheries Division. 11 Finally, there remains the question of whether other Tuvaluan lagoons presently have adequate wild pearl oyster stocks to support the immediate commencement of pilot culture activities. Anecdotal information strongly suggests that this is unlikely, since there is almost unanimous agreement in Tuvalu that pearl oysters are much more abundant in Nukulaelae than elsewhere. On this basis, it is probably realistic to assign further survey work a fairly low priority. However, Fisheries Division staff should continue to actively seek more detailed anecdotal information on outer island pearl oyster stocks, and should carry out survey dives in promising pearl oyster habitat, especially in Nukufetau and , when opportunity permits. 12 APPENDIX 1: Field station descriptions Station: 1 Depth (m): 2-22 Duration (min): 50 Remarks: Bommie, few coral heads, coralline algae, broken coral rubble. 1 dead pearl shell found. Station: 2 Depth (m): 3-4 Duration (min): 50 Remarks: Numerous coral patches,fine sand, few spondylids. Snorkelling,no pearl shell. Station: 3 Depth (m): 4-10 Duration (min): 25 Remarks: Patch reef,few coral heads, spondylids present. Poor visibility at 7m, no pearl shell. Station: 4 Depth (m): 4-18 Duration (min): 35 Remarks: Reef dropoff, fine sand/mud, seagrass and few beds of Halimeda. Poor visibility at 18m depth, no pearl shell. Station: 5 Depth (m): 5-15 Duration (min): 25 Remarks: Numerous coralline algal patches, murky and very fine sand. No pearl shell. Station: 6 Depth (m): 3-24 Duration (min): 40 Remarks: Numerous coral heads, limestone with coarse sand, few spondylids.Increase in suspended sediments at 24m depth, no pearl shell.

Station: 7 Depth (m): 2-4 Duration (min): 80 Remarks: Bommies, coarse sand/shale, seagrass. Snorkelling, no pearl shell.

Station: 8 Depth (m): 4-18 Duration (min): 20 Remarks: Live coral heads, some spondylids, green filament algal covering rubble, start of suspended sediments at 8m, no pearl shell.

Station: 9 Depth (m): 4-19 Duration (min): 25 Remarks: Patch reef, irregular algal ridge, coarse sand, rubble, filament algae. Steep dropoff at 14m, increase in suspended sediments at 18m depth, distance covered 135m. 13

APPENDIX 1: Field station descriptions (continued)

Station: 10 Depth (m): 9-15 Duration (min): 20 Remarks: Patch reef, blue green algae, no live coral, coarse sand, rubble. Distance covered 125m, increase in suspended sediment at 10m depth. Station: 11 Depth (m): 2-15 Duration (min): 28 Remarks: Coral heads, occasional live (branching) coral, coarse sand, some rubble, blue green algae also present. 2 pearl shells found amongst blue/green algae. Station: 12 Depth (m): 6-23 Duration (min): 36 Remarks: Bommies encrusted with Halimeda, numerous black sponges, sediment, rubble. 1 pearl shell (4cm) found on staghorn coral at 8m depth.

Station: 13 Depth (m): 5-20 Duration (min): 15 Remarks: Coral heads, algal ridge, coarse sand, some sediment, few spondylids. Increase in sediment at 20m depth, no pearl shell. Station: 14 Depth (m): 2-6 Duration (min): 50 Remarks: Coral patches, algal ridges, live staghorn coral also present. Snorkelling, no pearl shell.

Station: 15 Depth (m): 2-13 Duration (min): 18 Remarks: Patch reef, algal ridge, coarse sand, some sediment, few spondylids. Plateau at 13m depth. Generally reasonable habitat but no pearl shell. Station: 16 Depth (m): 6-14 Duration (min): 7 Remarks: Reef dropoff, medium sand/sediment, coral head with bushy Halimeda. No pearl shell.

Station: 17 Depth (m): 8-20 Duration (min): 25 Remarks: Patch reef, some bommies covered with algae, lots of sediment. Visibility reduced to 3m as descending into deeper water. 14 APPENDIX 1: Field station descriptions (continued) Station: 18 Depth (m): 0.5-1 Duration (min): 30 Remarks: Patch of live coral heads, staghorn coral, seagrass. Snorkelling, no pearl shell. Station: 19 Depth (m): 16-22 Duration (min): 45 Remarks: Gradual dropoff outside surf, top slope all staghorn, outer slope coarse staghorn, plate-like corals. No pearl shell.