Preliminary study on comparative morphometry of Cynothrissa mento (Regan, 1917) from Ologe, Badagry and Epe Lagoons, Lagos, Nigeria

The morphometric characters of Cynothrissa mento from three major Lagoons (Ologe, Badagry and Epe) in Lagos, Nigeria were compared to assess the possibility of this fish species from the three Lagoons belonging to the same sub-population. The length-weight relationships (LWR), and condition factors (CF) of the fish were also described as well as the physico-chemical parameters of the three water bodies. The study was conducted between May, 2009 and April, 2010 and monthly sampling of fish and water was done in each sampling site. Seven7 physico-chemical parameters were assessed and these are; temperature, pH, salinity, turbidity, dissolved oxygen, total alkalinity and total hardness. A total of 294 specimens (Ologe 60, Badagry 174 and Epe 60) of C. mento were collected from the landings of the local fisher folks from the sampling sites. Seven morphometric characters; total length (TL), standard length (SL), body depth (BD), head length (HL), head depth (HD), eye diameter (ED) and interorbital width (IW) were measured. There was no significant difference (p > 0.05) in all the physico-chemical parameters measured among the sampling sites except pH. Coefficient of difference revealed that the C. mento from the three lagoons are uniform in all the morphometric parameters examined, which means that the specimens from the three sampling sites do not belong to different sub-populations. The growth coefficient/slope (b) values obtained for the fish species from the sampling sites ranged from 2.27 - 2.53, and differed significantly (p < 0.05) from 3, which indicates that most of the fish species have negative algometric growth