On the Parallelism of Nested For-Loops Using Index Shift Method.

Abstract

The influence of size, sex and season on the feeding regime of S. membranaceus were examined over a period of 24 months in Jebba Lake, Nigeria using frequency of occurrence, numerical, gravimetric and index of Relative Importance (RI) methods. Dietary composition and feeding intensity were sex dependent. RI established that there was a progression from a detritivorous diet in fish below 20 cm Standard Length (SL), through a transitional planktivorous phase (20-27 cm, SL), to a predominantly molluscivorous/insectivorous diet in fish above 27 cm SL; thus indicating a switch from a relatively passive filter-feeding habit when young to an active predatory habit at adult stage. Food preference also varied with season hence intraspecific competitions were low. Abundant food and ability to evolve trophic strategies that ensure optimum foraging in spite of seasonal changes enable S. membranaceus to maintain its overwhelming prominence and wide distribution in Jebba Lake.