Browsing by Author "Kithakeni, Twalibu M."
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Item Effect of Fishing on Sea Cucumber Ecology(2013-03) Kithakeni, Twalibu M.Two species of sea cucumber in the selected sites were studied in 2006-2008 and compared with MPA. The work assesses abundance, density, distribution, size structure of two commercially important species (Holothuria scabra, and Holothuria nobilis) in 3 different habitats in 4 selected sites from April, 2006 to April 2008. The site selection was based on separate geographical locations Dar Es Salaam and Mafia; different levels of fishing pressure; MPA – (Kitoni), LFA (Buyuni) and IFA (Kunduchi and Magemani) but with similar types of substrata (sand, mud and rock) habitats of sea cucumbers thus providing an important and unique opportunity to envisage effects of exploitation on the sea cucumber ecology. Mean abundance, distribution and modal sizes differ among sites for both H.scabra and H. nobilis indicating the different levels of fishing distruction among sites. Significant difference in size was on Kunduchi – Buyuni (p<0.01), Kunduchi – Kitoni (p<0.001), Buyuni – Magemani (p<0.001) and Magemani – Kitoni (p<0.001,) while that of H. nobilis the significant difference was only between Kunduchi – Magemani (p < 0.05) and Kunduchi – Kitoni (p < 0.05). Temperature, salinity, organic matter and bio-cover correlated variably with density of H. scabra and H. nobilis. Based on these results the estimated a stock of 11109 individuals for H. scabra and 2841 for H. nobilis. The study revealed reduced modal sizes, diversity and density of sea cucumbers in the areas outside MPA and inaccessible sites as a result of overfishing and the biological constraints. Other factors e.g. processes affecting the input of planktonic larvae and physical oceanographic features can as well shape local patterns of abundance. The results envisage the need for spatial planning of fisheries management and conservation.Item A Framework for Addressing Socioeconomic and Management Aspects of Sea Cucumber Resources in the Western Indian Ocean(2007) De la Torre-Castro, M.; Ochiewo, Jacob; Kithakeni, Twalibu M.; Pinault, M.This paper reveals how the socioeconomic and management objectives of a three-year sea cucumber project in the western Indian Ocean (WIO) (cf. Conand et al. 2006) will be addressed. A conceptual model of sea cucumber resource dynamics is presented. This model encompasses multiple levels and considers the main structures of the sea cucumber fishery such as fishing and collection grounds, resource users and other stakeholders involved in the fishery (e.g. fishers, middlemen and importers), the links between stakeholders, villages and countries, and the associated management initiatives at different levels. This framework is promising when analyzing the sea cucumber fishery from a holistic perspective, considering both social and ecological interactions. The results of the study will provide knowledge and management advice for the sustainability of the sea cucumber fishery in the WIO; however, the framework is not restricted to the WIO, and may be adapted to other fisheries.Item Sea Cucumber Fishery in Tanzania: Identifying the Gaps in Resource Inventory and Management(2005) Kithakeni, Twalibu M.; Mgaya, Yunus D.The story of over-exploitation of sea cucumbers in Tanzania has been repeated in many locations throughout the Indian Ocean. Collection methods include (i) hand-picking, (ii) collection by free diving using homemade goggles and (iii) SCUBA diving in a few locations. Neither fishery regulations, nor mariculture or resource inventories have been conducted as steps towards management and conservation of sea cucumber in Tanzania. Data was compiled from various works carried out on the sea cucumber resource in Tanzania and from questionnaires that were given to sea cucumber dealers and fishery officials. This approach revealed several factors underlying the lack of management of sea cucumber resources, notably (a) the extent to which the stock size of this resource is known to fishers of Tanzania, (b) the lack of a proper management framework and stock assessment on sea cucumbers, and (c) scientific orientation of funding agencies and research findings contrary to dealers’ level of education and technological capacity. The appropriate actions to achieve successful management of sea cucumbers should be taken in phases. That is, to raise the fishers awareness, carry out resource assessment, implementation of regulations and establishment of a pilot small-scale mariculture activity of the most known species in Tanzania, Holothuria scabraItem Sea Cucumbers in Tanzania(2007) Mgaya, Yunus D.; Kithakeni, Twalibu M.Sea cucumbers constitute one of the important marine resources of Tanzania (Semesi et al. 1998) and there has been a rapid expansion of sea cucumber exploitation at some sites in Tanzania (Mgaya et al. 1999). The sea cucumber fi shery developed without baseline biological data and without any monitoring. Therefore to-date, Tanzania has unknown and unquantifi ed sea cucumber resources though the fi shery provides income to local collectors and generates export earnings (Mmbaga and Mgaya 2004). The fi shery is largely artisanal with a small commercial operation monopolised by a few exporters. Exploitation occurs year-round on reefs close to shore with collection peaking during periods of light winds and trips can be made to the outer reefs. The level of exploitation differs from shore to shore depending on fi sher folk experience, number and category of fi shers, fi shing techniques and season. Sea cucumbers are purchased by a number of traders based in Dar es Salaam, Tanga and Zanzibar from where they are exported to eastern Asia mainly Hong Kong SAR (China) and Singapore (Unpublished data). The increase in export of beche-de-mer was observed from 1980s (< 200 mt per annum) to 1992 (617 mt); exports have continued to decline thereafter (Marshall et al. 2001). These authors report further that the number of offi cial beche-de-mer exporters on the Tanzania mainland has decreased from 23 in 1993 to 8 in 1997 and that the exporters have largely halted exports as a result of the declining profi ts.Item Some Aspects of Sea Cucumber, Holothuria Scabra (Jaeger, 1935), Along the Coast of Dar Es Salaam(2002) Kithakeni, Twalibu M.; Ndaro, Simon G. M.Some aspects of the biology of the sea cucumber Holothuria scabra Jaeger, 1935 were studied along the coast of Dar es Salaam. Samples of H. scabra were collected from Kunduchi and Buyuni between January and December 1999. The abundance of Holothuria scabra was higher in Buyuni (3951) than in Kunduchi (1176). However, the level of exploitation per year from far reefs was higher in Kunduchi than in Buyuni. Sea cucumber harvesting by villagers is done monthly on intertidal areas and from reef flats near to the villages. Higher catches from Buyuni were recorded during August and November (perhaps due to light winds such that trips could be made to far-off reefs), while the catch from Kunduchi was relatively low throughout a year. The length-frequency distribution of H. scabra was found to be unimodal, with most individuals ranging between 8.5 cm and 26.5 cm. The species showed continuous breeding with peaks between May and September and December. The average size at first maturity in H. scabra was 16.8 cm.Item Some Aspects of Sea Cucumber, Holothuria Scabra (Jaeger, 1935), Along the Coast of Dar Es Salaam(2002) Kithakeni, Twalibu M.; Ndaro, Simon G. M.Some aspects of the biology of the sea cucumber Holothuria scabra Jaeger, 1935 were studied along the coast of Dar es Salaam. Samples of H. scabra were collected from Kunduchi and Buyuni between January and December 1999. The abundance of Holothuria scabra was higher in Buyuni (3951) than in Kunduchi (1176). However, the level of exploitation per year from far reefs was higher in Kunduchi than in Buyuni. Sea cucumber harvesting by villagers is done monthly on intertidal areas and from reef flats near to the villages. Higher catches from Buyuni were recorded during August and November (perhaps due to light winds such that trips could be made to far-off reefs), while the catch from Kunduchi was relatively low throughout a year. The length-frequency distribution of H. scabra was found to be unimodal, with most individuals ranging between 8.5 cm and 26.5 cm. The species showed continuous breeding with peaks between May and September and December. The average size at first maturity in H. scabra was 16.8 cm.