Journal of the Marine Biological Association of India

Carangid fishery and yield per recruit analysis of Caranx carangus (Bloch) and Caranx leptolepis Cuvier and Valenciennes from Tuticorin waters

Volume 36 Issue 1&2

H. Mohamed Kasim and K M. S. Ameer Hamsa

Abstract

An estimated annual average catch of 205.8 t of carangid were landed during 1981-83 by traditional fishing units. The gearwise catch composition of carangid was observed. Depthwise variation in the abundance of carangid was observed from the catch rates of these traditional gears. During 1984-87, an estimated annual average catch of 12563 t of carangid were landed in which the trawl net units landed 1184.8 t and drift gill net units 71.5 t. Though the abundance of carangid varied from year to year, in general, it appears there is one pronounced abundance during July to November and another less pronounced during January to April. The annual average species composition of trawl net landings was also studied. Based on the catch in number, effort and length frequency data, the estimated growth parameters of Caranx leptolepis are L_∞ 213 mm, K 1.4283 and ta -0.0151 and of C. carangus are L_∞ 498 mm, K 0.7689 and to -0.0455. Estimated growth in weight of these species could be obtained from the length weight relationship given. The natural mortality coeffcient M is estimated to be 2.19 for C. leptolepis and 1.18 for C. carangus from the life span Tnux of these species. The total mortality coefficient Z varied from 4.33 in 1986-87 to 8.33 in 1984-85 for C. leptolepis with an average of 6.10 in trawl net. For C carangus, the Z varied from 4.48 in 1985-86 to 9.69 in 1984-85 with an average of 6.54 in trawl net and in drift gill net it was 2.80 in 1986-87 to 4.77 in 1985-86 with an average of 3.92.

The yield per recruit for 3 different M/K ratios obtained for these two species indicate that. C. leptolepis is not exposed to higher fishing pressure as in the case of C. carangus by trawl net and the effort of trawl net may be increased further to match the F_max to realise enhanced production of this species. Whereas, in the case of C. carangus further increase in trawl net effort may not be favourable unless the age at first capture is increased by increasing the cod end' mesh size which is not practical as the main aim of trawl net is to exploit some other resources like prawns and C. carangus is only a bycatch. However, exploitation of this species by drift gill net may be increased by increasing the mesh size further to enhance the age at first capture as the prevailing age at first capture is only 0.28 yr, whereas the optimum age of exploitation is 1.08 yrs.

Date : 30-12-1994