The Sea Cucumber Holothuria (Halodeima) atra (Jager, 1833), in South Tarawa Lagoon (Republic of Kiribati): Environmental Variability, Population Biology and Fishing Pressure
Holothuria atra or lollyfish is the most common sea cucumber in the Pacific and Indian Oceans. The current status of Holothria atra at 13 sites of South Tarawa lagoon (Republic of Kiribati) was established by using biological surveys and fishers' questionnaires. A preliminary investigation was conducted in order to assess how and why environmental variability and fishing pressure have affected the spatial and temporal distribution, mean abundant and mean size of this species at the sites. The 13 sites were selected randomly, and marked with a GPS on the map of South Tarawa. Sedimentary characteristics were determined for each site, and a qualitative assessment of sites health was made. Lollyfish length, biomass and abundance and transect density were calculated for each site. The weight of organic matter content and size of sediment sample were determined. Data were analysed using Kruskal-Walis (KW) and Repeated measures (RM) ANOVA tests. This thesis shows that the environmental variability could not offer reasons as to why the biological data of lollyfish varied from one site to another. However, other factors that were tested may explain the variation in biological data. Fishing pressure is one of those parameters that can regulate the lollyfish distribution and density and responses from local fishers indicate that fishing pressure is high and that the lollyfish resource is under considerable harvest pressure. Dissolved oxygen concentration in the water column and in the sediment may be also involved in the variation in lollyfish distribution and density but this was not tested. The findings of this research lead to a number of recommendations for the sustainable harvest of lollyfish in Tarawa lagoon. These include consideration of gear restrictions, lollyfish size and number limits, and the establishment of marine protected areas under co-management arrangements.