Collection of juvenile mullet species from a brackishwater tidal farm in Nigeria

The major constraint to the development of aquaculture in Nigeria has been the non-availability of fingerlings in required numbers of cultivable species. A specifically designed trap to collect mullet (Liza falcipinnis; Liza grandisquamis) juveniles during high tides was successful in collecting juveniles year-round. The collectors was more successful during night spring tides than during neap tides or daytime collections. Thus, the use of traps, especially in the tidal zones, could provide a cost-effective method of stocking fish farms by collecting juveniles and seed from the natural environment

Species composition, length-weight relationship and condition factor of landed fish catch of Elechi Creek, Niger Delta

Information on length-weight relationship and condition of landed fish catch at Elechi Creek is inadequate despite different human activities taking place there. Fish specimens were procured twice monthly between April and September 2012 from artisanal fishers and middlemen at three landing sites (stations) in study area. Lengths and weights of fish were determined to nearest centimeter and gram using standard methods. Fulton’s condition factor was estimated following Bagenal and Tesh method to determine health status of fish. One thousand specimens comprising of 15 species from 15 families were examined. Tilapia guineensis (Cichlidae) (150, 15%) recorded highest number while Microchirus boscanion (Oleidae) accounted for lowest number (23, 2.3%). Sizes of fishes included small-sized (5.3 cm to 7.6 cm) to large-sized fishes (23.8 cm to 29.4 cm). Considering stations, the highest number of fishes was recorded in Station 3 (438 specimens) while the lowest was in Station 1 (257 specimens). Chrysichthys nigrodigitatus (b=3.75), Mugil cephalus (b=3.02) and Atherina formis (b=3.46) exhibited positive allometry growth while Pseudotolithus elongatus (b=2.55), Eleotris africana (b=2.79), Sardinella maderemsis (b=2.04), Periophthalmus barbarous (b=2.77), Microchirus poscanion had negative allometry growth. Five species of fish had condition factor below 1 which signified that Elechi Creek was not conducive for their growth.Keywords: Fish catch, growth pattern, wellbeing, anthropogenic inputs, specie

Sex ratio, gonadal development and fecundity of the grunt, Pomadasys jubelini (Cuvier, 1830) in the new Calabar-Bonny River, Nigeria

The sex ratio, gonadosomatic index, stages of gonadal development and fecundity of the grunt, Pomadasys jubelini in the New Calabar-Bonny River were investigated. P. jubelini had a sex ratio of 1: 2.1 (male to female). Gonadosomatic index ranged from 0.33 to 7.29% with a mean of 2.89+0.08%. High gonadosomatic indices were recorded from September to October, which indicates the production period of the fish. Two stages; maturing and mature were observed for male fish while quiescent, maturing and mature were observed for female fish. Fecundity ranged from 9,085 to 37,926 eggs and a mean of 25,852+432 eggs. This is an indication that P. jubelini has low fecundity. Fecundity-body weight and fecundity-body length were positively correlated. Fecundity-weight relationship was Log F=0.1243+2.74 Log W (r=0.950). Fecundity-length relationship was Log F=0.0247 + Log 1.779 log L=(r=0.114), Fecundity was more related to weight than length. P. jubelini begins spawning during the rainy season in marine and estuarine environments. During this period large number of fingerlings and juveniles are in abundance. The results of this study will assist in increasing the knowledge of the reproductive biology of P. jubelini which is relevant in aquaculture development of the species.Keywords: Fecundity, gonadal development, gonadosomatic index, New Calabar-Bonny River, Pomadasys jubelin