Journal of the Marine Biological Association of India

Volume 52 Issue 1
Ray fishery by trawlers off Chennai and some aspects of biology of the scaly whipray Himantura imbricata (Bloch & Schneider, 1801)
Shoba Joe Kizhakudan, G. Mohanraj, T. Hameed Batcha and S. Rajapackiam
Abstract
Rays are important components in the elasmobranch landings by different gears at Chennai fisheries harbour, contributing about 75.4% to the annual average elasmobranch landings. The annual average
catch of rays during 2002-�07 was 588.3 t and the maximum catch of 1297.4 t was recorded in the year 2002. Eleven species contributed a major portion to the landings of rays by trawlers at Chennai,among which Himantura jenkinsii dominated the catch, forming 38.6% and H. imbricata, 8.0%. The disc width (DW) range of H. imbricata in the landings was 110-229 mm and 130-289 mm for males and females, respectively. The annual average mean size was greater in females. The annual average sex ratio (M:F) was 1:1.11. The disc width-weight relationships were W = 0.00022DW2.676 and W = 0.00005DW2.965 for male and female, respectively. Analysis of covariance showed that the slopes differed significantly, at 5% level, between the sexes. More than 95% of fishes sampled were in wellfed condition. Analysis of gut contents revealed H. imbricatato be a benthic carnivore feeding mostly on small crustaceans, cephalochordates, molluscs, polychaetes and small fishes.
Keywords
Chennai, ray fishery, Himantura imbricata, disc width-weight relationship, gut contents
Date : 20-09-2010