STOCK STATUS AND SOME ASPECTS OF THE BIOLOGY OF THE PINK EAR EMPEROR LETHRINUS LENTJAN (LAĆEPÈDE, 1802) IN SOUTH COAST KENYA
A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Fisheries of Pwani University October, (1.228Mb)
MROMBO, NATHAN LENJO
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The pink ear emperor Lethrinus lentjan (Laćepède, 1802) is among three demersal fish species dominating catches in the artisanal fishery along the Kenya coast. Available data indicate that total landings of L. lentjan have declined over the past decade due to overexploitation driven by increased fishing effort. However, little information on its biology is available in the Kenya coast. This study therefore was aimed at assessing the species stock status and some biological aspects including Length-weight relationship (LWR), body condition, and reproduction. Sampling was done at selected fish landing sites; Msambweni, Shimoni, Majoreni and Vanga from September 2016 to February 2017. A total of 575 L. lentjan individuals were collected for this study. Samples were measured for their total length (TL, cm) and body weight (BW, g) on site while some were collected and transported to the laboratory for dissection to determine sex and gonad at maturity. Selected biological aspects including mortality, exploitation rate, length-weight relationship, condition factor, fecundity, and size at massive maturity (L50) were determined using standard methods. Length frequency analysis of the species indicated that L. lentjan was being strongly exploited at E = 0.55 which is above the optimum level of E = 0.5. Total length was very strongly associated with body weight as expressed by the equation Log W = 2.95 Log TL - 1.78 and r2 = 0.98. Growth was allometric with the length exponent b=2.95, which was significantly <3. Mean fecundity was 89,573 ± 9,841. Gonadosomatic index was highest in January (2.08 ± 0.20) suggesting possible peak spawning period for this species. The study provides critical baseline scientific information on L. lentjan useful in formulating strategies for the sustainable management of its fishery in south coast Kenya. Therefore, there is need for restriction on use of destructive fishing gear such as beach seine to reduce pressure on the L. lentjan fishery in south coast Kenya.