International Journal of Aquaculture, 2018, Vol.8, No.6, 38-42
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about 300 km long and discharges into the Atlantic Ocean through a series of creeks and lagoons. The fishermen
operate from non-powered dug-out canoes and use a variety of gears which include gill nets, long lines, traps and
cast nets.
Figure 1 Map of Ogbese River (Ajakaye et al., 2017)
1.2 Fish sampling
P. altipinnis
specimens were collected once weekly, directly from fresh landings of fishermen from Ogbese River
between May 2014 and April 2015. The specimens, totaling 240, were selected randomly to include various size
ranges. The specimen were sorted into two size groups namely, juveniles (<10.00 cm) and adults (>10.00 cm).
Records of total length (cm) and body weight (g) measurements of individual fish were made before preserving
them in ice. The specimens were dissected, sexes were noted, gonad development were assessed and classified
according to Clay (1979) and matured gonads were preserved in formol-saline (4% formalin plus normal saline
ratio 1:1) prior to fecundity studies. Fecundity was estimated by gravimetric method, each preserved ovary was
weighed and the number of eggs from three 10 g sub-samples was counted (Abidin, 1986). The means of the total
number of eggs in the sub-samples were determined while the total number of eggs per ovary was determined by
the formula:
Where: F = fecundity, G = total weight of eggs, g = weight of sample eggs, n = number of eggs
2.3 Data analysis
Length-weight relationship was calculated using Le Cren (1951) equation W = aLb. The data were transformed
into logarithms to determine the growth pattern thus:
Where W = body weight of fish (g), L = total length of fish (cm), a = constant, b = exponent. The condition of the
fish was expressed by Fulton’s condition factor (K), calculated using the formula (Bannister, 1976):
Where K = condition factor, W = weight in g, L = Length in cm. The gonadosomatic index (GSI) was calculated
