Stock assessment of the penaeid prawn Metapenaeus monoceros Fabricius along the Indian coast

The annual average production oi Metapenaeus monoceros during 1985-89 was 10 286 tonnes, nearly 7.2% of the penaeid prawn landings in the country. Tlie west coast accounted for 71.2% and the east coast for the rest. Among the maritime states, Maharashtra ranked first in production (27.2%) followed by Kamataka (22.3%) and Andhra Pradesh (21.3 %). The estimates of von Benalanffy growth parameters, L" and K (annual) were 180 mm and 1.8 for males, and 210 mm and 1.8 for females. This prawn attained a size of 149 mm and 173 mm in males and females, respectively, at the end of 1 year. The instantaneous total mortality coefficient (Z) ranged between 4.28 and 8.05 in males, and between 4.17 and 6.33 in females. Natural mortality coefficient (M) was 1.8 in both the sexes. Yield per recruit studies indicated that for an age of 0.59 year at first capture the fishery generated a steadily increasing yield up to 10 000 tonnes for an annual effort of 1 578 000 boat trips (16 670 000 fishing hours) at which the annual fishing mortality (F) is 3.76 and the exploitation ratio (E) is 0.67. Beyond this level of exploitation the increase in yield was only marginal. Even though the average aimual yield during 1985-89 was marginally lower than the maximum sustainable yield (MSY) of 10 993 t, the catch during 1987 and 1988 exceeded MSY level. Hence the desirability of maintaining the effort at the present level to obtain sustainable yields is mentioned