College of Agricultural Sciences and Fisheries Technology
Permanent URI for this community
Browse
Browsing College of Agricultural Sciences and Fisheries Technology by Subject "Abundance"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
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 Nearshore Fish Resources and Fisheries around Kigoma, Eastern Coast of Lake Tanganyika(1992) Ndaro, Simon G. M.The fish habitats along an inshore water stretch along the eastern/central coast of Lake Tanganyika are discussed and a quantitative analysis of the species composition, distribution and abundance of the littoral fishes within the area of study is presented. Seventy-one species of fish belonging to 48 genera and to 15 fish families were collected and identified during the study. The majority of species belonged to the Cichlidae family. Intensive beach seining for clupeids is suggested as one of the causes of low fish biomass in the area surveyed. The areas south of Kigoma appeared to contain more fish, with average catch rates of 11.7 kg/haul than those north of Kigoma where average catch rates of 7.6 kg/haul were recorded. Some suggestions for improved management of these resources are given.