Size, Food and Age of Commercially Exploited Trichiurus lepturus Linnaeus Caught Off Negombo and Beruwala, in Sri Lanka

Abstract

Six species of Family: Trichuridae are essential shore line fish in Sri Lanka, which is highly popular as dry salted or fresh fish consumption. Trichurus lepturus is the most common species in catches out of the about six, the purpose of present study was to fmd the size, food habit and age of T.lepturus. Food habit and the age ofT.lepturus was studied from August 2005 to January 2006. Samples were to ice boxes from Negombo and Beruwala fishing area. Beach seines at other landing sites were visited twice a month. T. lepturus of about 20% of randomly selected fish was measured for total length. About 10-15% fish of the above sample was taken to the laboratory after injecting 5% formalin through anus. Gut content were identified to nearest taxon and their number were recorded. The result indicated that the main food of T. lepturus consist of Sardinella sp., Leiognathus sp., Polynemus sp., Secutor sp., Anchovelia sp., Mugil sp. and shrimps. The type of food varied with the age. Small fish consumed shrimps and Anchovelia sp., where as relatively large fish consumed Sardinella sp. The amount of fish consumption increased linearly with the size. The mean length offish at age I, II, III, IV, V, VI, VII, VIIl, IX and X was 28.27cm, 48.27cm, 63.01cm, 73,49cm, 81.02cm, 86.44cm, 90.33cm, 93.12cm, 95.l3cm and 96.l8cm respectively; and the La, K and 10 were 100.28cm, 0.33 and 0.00 years respectively for Negombo. The mean length offish at the age I, II, III, IV, V,VI, VII, VIII, IX and X was 30.31cm, 51.46cm, 66.22cm, 76.52cm, 83.70cm, 88.71cm, 92.21cm, 94.65cm, 96.35cm and 97.53cm respectively; and the La, K and 10 were 100.28cm, 0.36 and 0.00 years respectively for Beruwala.