Report on Length, Weight and Sex Survey of Nile Perch (lates Niloticus) In Lake Victoria, Tanzania

Abstract

This report presents the length-weight relationship parameters (a and b) for 559 Lates niloticus, size composition, sex, maturity stages, length at first maturity and food examined during February 2004 from four landing sites and four processing industries. Estimates of “b” varied between 2.5045 and 3.3537 with mean of 2.8781 (+ 0.3593). The length-weight relationship was isometric. The maximum total length (TL) recorded was 109 cm while the minimum was 35cm. The modal length for combined data from all landing sites was 70 cm, which is the same as that observed from fish processing industries. The highest modal length (80 cmTL) in landing sites was observed at Kayenze station. Males outnumber females by the ratio of 2.3:1 and mature earlier at 64 cmTL than females, which attain sexual maturity at 66 cmTL. Bwai have comparatively more food for Lates niloticus than other areas with condition factor “a” equal to 0.0118. The main food for Lates were Haplochromines and Silver cyprinids, Rastrineobola argentea. Other food items eaten by Lates were Brycinus spp., Bagrus dockmac and Caridina nilotica. Majority of Lates niloticus in this survey contains empty stomachs (75%).