Asian Journal of Microbiology, Biotechnology & Environmental Sciences Paper

THE FISHERY, GUT LENGTH AND FOOD PREFERENCES OF THREE COMMERCIALLY EXPLOITED SPECIES (CYNOGLOSSUS SENEGALENSIS, LIZA FALCIPINNIS AND POMADASYS JUBELINI) IN TROPICAL OPEN LAGOON, NIGERIA

B.E. EMMANUEL, M.N. ADIGWE AND N.F. ALADETOHUN

Abstract

The fishery, gut length and food preferences of three commercially exploited species: Cynoglossus senegalensis, Liza falcipinnis and Pomadasys jubelini in Lagos Lagoon, Nigeria was investigated between August and November, 2005. The choice of cast net for this study was as a result of its selectivity and conservation role. The size distribution of the three fish species followed a normal pattern with distinct modes. The length frequency distribution indicates that C. senegalensis, P. jubelini and L. falcipinnis studied were constituted of multiple cohorts. The length - weight relationships reflected a common general increase in weight with increasing length in L.falcipinnis and P. jubelini but not in C. senegalensis which exhibited a negative allometric growth with a b-value of 0.3 which is less than 3. The condition factors for the species examined did not differ significantly with respect to sex and size among the species. The general morphology of C.Senegalensis, P.jubelini and L. falcipinnis suggested that they are predatory fishes (C.Senegalensis and P.jubelini) and deposit feeder respectively. These species fed mainly on either crustaceans or and molluscs with other food items forming supplementary foods. They fed on variety of animals and there is also a considerable overlapping in their diets. The three species had no discrepancies in their preferences for food which increase intra specific competition and make it impossible for fish of different sizes to occupy the same habitat. The presence of organic detritus in the diets of the three species studied identified them as ileophagous species. The long gut recorded for L. falcipinnis is an indication that it feed mainly on plant materials and detritus. This study identified the different variety of food materials that these species feed on in the wide giving a clue to the feed formulation for the species for culture purpose.