Studies of holothurians (sea cucumbers or trepang) in Sulawesi have largely focused on deposit feeders and have included studies on ecology (Tamanampo, 1986), growth (Manu, 1988) and distribution (Massin, 1999). These studies suggest that diversity in this taxon in the region is high with up to 56 species being recorded in specific areas (Massin, 1999).Ten species new to the fauna of Indonesia were reported by Massin (1999). Holothurians are harvested for food and for sale to international food markets by artisanal fishermen throughout Indo-Pacific and Pacific regions. Harvesting for international markets has resulted in overfishing which has led to dramatic declines in densities throughout the region (Conand, 1990). This in turn has resulted in increased pressure on more remote stocks. Shallow-water deposit-feeding holothurians are easily collected by hand and snorkelling which increases their vulnerability to overfishing. Sustainable management could offset the problem of overfishing.

• To produce a photographic key of holothurian species present

• To map the distribution and habitat preference of different species

• To assess current exploitation rates of holothurians in the Wakatobi Marine National Park

Methodology and progress against objectives

To produce a photographic key of holothurian species

A photographic library has been initiated. Photographs were taken of all species of holothurians encountered during fieldwork and the resident professional photographer has also started to photograph other specimens. DR has been commissioned to write an article on holothurians for ‘the Biologist’ for the autumn and will incorporate as many Operation Wallacea photographs as possible. The following species have been photographed to date

Holothuriidae: Holothuria nobilis; H. coluber; H. impatiens; H.cf pardalis; H. edulis; H. scabra; H. hilla; Stichopus horrens; S. variegatus; S. cf quadrifasciatus; S. noctivagus; Actinopyga miliaris; A. lecanora; Bohadschia argus; B. marmorata; B. graeffei;

Synaptidae: Synapta maculata; Synapta species; Synaptula reticulata; Leptosynapta species

To map the distribution and habitat preference of different species

To utilise the large numbers of individual dives and observations undertaken by staff and volunteers in the area, three projects have been initiated under this heading.

•  Survey of the distribution of Bohadschia graeffei in the Hoga channel

Bohadschia graeffei is a large reef-dwelling holothurian that is not harvested commercially in the area. Consequently it may be one of the few species in the area that has near-natural populations.The aim of this project is to investigate factors affecting the distribution of Bohadschia graeffei in the Hoga channel.Divers recorded the following data opportunistically while conducting other surveys: site; depth; estimated length; substratum; and feeding activity. All surveys were carried out during daylight hours.

Thirty-five observations were recorded during July. Data confirm that the preferred habitat of B. graeffei is coral rubble between 3 and 18m [mean depth 10.7m (+/-3.5m)]. Most animals ranged between 19 and 55 cm mean 33.3 (7.6). 28 feeding 7 searching. During the study, some individuals were observed raising the oral region, although they were not spawning. This led to observers undertaking a number of behavioural observations in which individuals were transferred to other substrata. Data from these observations suggest that B. graeffei may be able to discriminate between feeding patches of different food quality. This hypothesis will be investigated further by additional field observations; by examining tentacle ultrastructure and substratum characteristics (organics & particulates).

• Survey of the distribution of Synaptula sp. on barrel sponges the Hoga channel

• Holothurian watch

The aim of this project is to compile a record for those species that can be easily identified by divers in the field. These include: Bohadschia argus, Bohadschia graeffeii, Thelonota ananas, Holothuria edulis and Stichopus variegatus. Information recorded includes: site, depth, substrate (sand, live coral, coral rubble, seagrass); estimated size, observer and date. Data on dives per site can be used to correct for repeat observations.

• Recommendations for sustainable management of holothurian resources

Before strategies for sustainable resource management can be recommended, two types of information must be acquired: the extent and size of the resource and the levels of exploitation. Surveys involved participation of Bajo fishers, Bajo staff employed by Operation Wallacea and volunteers.

Four belt transects in the reef crest were surveyed at night, when holothurians are more active, on Pulau Hoga during low-water spring tides (three in the sanctuary zone and one without). The method involved walking with a 2m bamboo rod along a 100m tape laid parallel to the reef wall; the transect was illuminated by hurricane lamps and torches and the survey team walked behind the illuminated area to avoid sediment disturbance. The survey was repeated in sea grass. For the reef –crest zone total holothurian densities are about 10 individuals per 200m^-2 2. The survey in the sea-grass zone revealed very low densities but was carried out under adverse weather conditions. Future work should include repeat surveys on Hoga and on the Sampela sea-grass beds where there is significant harvesting.

The major method whereby holothurians and other invertebrates are harvested is by reef and reef-flat gleaning (nyulu). Surveys of reef-gleaning activities and catch composition were monitored over two four-day periods during low spring tides (2-6 & 23-25 July). Over 40 invertebrate and up to 6 fish taxa are harvested by gleaning. Methods include hand collection and snares and trident spears. The taxa collected include Lambis sp., cones, Cypraeids, Angaria, mantids, algae, porcupine fish, urchins and up to 20 species of sea cucumber. A programme to monitor catches at monthly intervals for the next year has been initiated in collaboration with Operation Wallacea. Catch composition data will be analysed by season, age and gender of fishers and collection methods. This programme will complements the surveys of reef fish fishing activities and catch statistics undertaken by Operation Wallacea.

Contribution to data on distribution of holothurian species in Indonesia in the form of the final report to Operation Wallacea which will be produced by December 2001

Publications will be completed during 2002 on the following subjects

• the biology of holothurians (late 2001)
• Bohadschia distribution and substrate preferences (2002)
• Synaptula distribution on sponges (2002)

Voucher material comprising whole specimens and tissue samples of holothurians for the Bogor Museum of Zoology have been collected and will be deposited at the museum at the end of the season. Only samples of species which need confirmation have been retained.

Whole specimens : Holothuria nobilis; Bohadschia sp.; H. cf pervicax; H. impatiens; S. horrens; H. cf pardalis; Bohadschia sp 2.

Tissue samples for spicules: Holothuria scabra; H. coluber; H. hilla; Bohadschia sp.; Stichopus horrens;

Conand, C. (1990) The fishery resources of Pacific island countries. Part 2. Holothurians. FAO Fisheries Technical Paper: 272.2 143pp.

Manu, G.D. (1988) The study of some aspects of Holothuria scabra (Jaeger) in Likupang Share, Unpublished thesis, Universitas Sam Ratulangi, 35pp.

Massin, C. (1999) Reef-dwelling Holothuroidea (Echinodermata) of the Spermonde archipelago (south-west Sulawesi, Indonesia). Zoologische Verhandelingen. 329, 144pp.

Tamanampo, J. F.W.S.(1986) The analysis of the trepang communities (Holothuroidea) in coral reef plateau territorials of the southern Bunaken Island. Unpublished thesis, Universitas Sam Ratulangi, 58pp

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