SPECIES COMPOSITION, LENGTH-WEIGHT RELATIONSHIP AND REPRODUCTIVE ACTIVITY OF EPINEPHELUS GROUPERS (PISCES: SERRANIDAE) FROM SOUTH COAST KENYA INDIAN OCEAN WATERS OGONGO,

Abstract

Globally, coastal and estuarine ecosystems are the most productive ecological systems providing essential ecosystem goods and services to the adjacent coastal populations. The ecosystems are however increasingly being threatened by anthropogenic activities leading to biodiversity loss and widespread impacts on important fishery species forming key pillars of many small-scale fisheries along the coast such as groupers. Epinephelus grouper species composition, LWR, and reproductive activity study was undertaken for eight (8) months beginning from December, 2013 from south coast Kenya Indian Ocean waters to provide data and information needed for supporting the fishery conservation management measures. Samples were collected for 3 consecutive days in each month from the artisanal fishermen in Msambweni, Shimoni and Vanga where the fishery is well established. Underwater visual censuses (UVCs) were further conducted to validate the landed species occurrences. Detailed searches were undertaken to determine the presence of the individual Epinephelus grouper species within ~10 and 2.5-m width bands on either sides of the set transect lines at the fishing grounds and encountered individuals identified to species level, enumerated and data recorded by the same observer to ensure consistency. Likewise, samples collected from the artisanal fishers were also sorted to species level, total length (TL, cm) and body weights (BW, g) measured for use in species composition; LWRs; and reproductive activity determinations. The species gonado-somatic indices (GSI) and sex ratios were determined from sexed, dissected and measured gonad weight (GW, g) results. The study revealed existence of 30 Epinephelus grouper species with varied individual numbers in which E. fasciatus and E. undulosus were the most and least abundant respectively. The species had similar (p > 0.05) site distributions; allometric LWRs (p < 0.01; b < 3); female favoured sex ratios; and reproductive activities occurring throughout the year with peaks from April through July