Interaction of the mormyrid fish Mormyrus kannume (Forsskål, 1775) reproduction and feeding intensity with the environment in a Nile Delta Canal,Egypt
Egyptian Journal of Aquatic Biology and Fisheries
The effect of environmental factors on the fish biological parameters and their quantification was investigated in this study during the period from January 2005 to January 2006. Bahr Shebeen Canal is a Nile canal that represents a fishery resource in the Delta of Egypt, where Mormyrus kannume shows a scanty abundance. During the period from of June to September, there was a chance to examine such interaction. The obtained results revealed that the fish spawn over an extended period, from
... period, from November till May, with two main peaks of spawning activity namely: November-December and February-April. Consequently, the gonadosomatic index (GSI) could not be correlated significantly with variation in either temperature or photoperiod. In those periods of spawning activity, the fish showed the lowest feeding intensity; i.e., low abundance. This was also quantified mathematically by significant correlations between the seasonal average (excluding winter) of stomachsomatic index (SSI) and either average daily temperature (T) and photoperiod (PP) for females and to a lower extent with males. These relationships were negatively correlated, and more significant among females than males, that was attributed to a higher activity of feeding among females. Also, the fish reproduction and feeding activities were correlated significantly with electrical conductivity and rainfall. This indicated that the fish are subject to the effect of associated environmental parameters interacting with their biology. The susceptibility of this fish species to change in those variables indicates its vulnerability to any adverse climatic change. The relationship between each of fecundity, egg diameter and gonadosomatic index and the female length or age were also examined and discussed, and the mathematical correlations were presented.