Reproductive Characteristics of the Elephant-snout Fish Mormyrus kannume Forsskal, 1775 from the Nile, Egypt

In the present study, some reproductive parameters including sex ratios, maturity stages, length and age at first maturity gonadosomatic and gonad indices, egg diameter and fecundity of Mormyrus kannume from the Nile, Egypt, were estimated in relation to standard length, weight, age and months. Other population parameters describing such population were also estimated. Different patterns of variations were recorded in these parameters. Overall sex ratio was significantly balanced in the Nile but not in the lacustrine locality: Lake Nasser. The females and males of M. kannume reached maturation at 31.7 and 31.5 cm with reproductive load of 0.754 and 0.748, respectively. Monthly variations in ED were evident with similar variability in GSI and GI. ED has its highest values in April and May and its lowest values in November and December (corresponding to highest fecundity). No association between ED and age groups whereas ED showed variability among maturity stages. Fecundity exhibited variability with age, length and months in the same locality. Fecundity highest average value was recorded in December (126236811).There is no association between fecundity and maturity stages and fish condition factor. The fecundity increased with age groups and has its highest values in age group I and II and lowest one in age VI. Fecundity also showed variations with time and locality when compared with other studies. In spite of estimation of its relation with other variables in univariate term, fecundity and variables controlling it were best modeled by stepwise multiple linear regression which isolated fish size, egg diameter and gonad index to be the best significant factors influencing fecundity and valid for prediction. In conclusion, M. kannume is a fecund fish with variations in time and localities.