Exploitation of prawn resources by trawlers off Kakinada with a note on the stock assessment of commercially important species

Annual prawn landings by trawlers operating from Kakinada increased gradually from 132 t in 1967 to 6,191 t in 1977 and declined abruptly to 2,026 t in 1978. Effort in trawling hours also indicated more or less a similar trend. The annual CPH indicated four phases in the abundance of prawns over the 12- year period. The annual percentage composition of prawns in the trawler catches varied from 16.7 in 1968 to 30.2 in 1972 with the average at 25 %. Although 38 species of penaeids and a number of nonpenaeids were represented in the catches, only Metapenaeus dobsoni (28.3%), M.monoceros (11.9%), M. brevicornis (6.6 %), M. affinis (5.9 %), Penaeus indicus (4.8 %) and P. monodon (4.4 %) formed the mainstay of the fishery. However, during 1977 non-penaeids represented by Acetes erythraeus, Nematopalaemon tenuipes and Hippolysmata ensirostris formed about 55 % of the prawn catches relegating the penaeids to a secondary status. Length-frequency distribution of penaeid species indicated that there was a decline in the proportion of larger size groups in the latter years. MSY and FMSY have been calculated for different species of penaeids to assess the present status of the stocks of these species. For the penaeids as a group the MSY has been estimated at 2,589 t. The study indicates that almost all the penaeid species are being harvested at the optimum level and any further increase in effort may lead to overfishing of the stocks