Stock characteristics and population dynamics of Heterocarpus woodmasoni Alcock

Heterocarpus woodmasoni Alcock, 1901 is a major species among the deep sea prawns landed along Kerala coast, India. This paper describes the stock characteristics and population dynamics of H.woodmasoni which constituted the exploited stock in commercial trawlers. The length composition of male H.woodmasoni ranged from 50 to 150 mm in total length with a modal length of 97 mm. Females ranged from 40 to180 mm TL and the modal length was 92 mm. Based on the length composition of male and female prawns, the growth parameters were estimated as male: Lt = 160.59 [1 - exp-0.82( t +0.97)]; female : Lt = 188.0 [1 - exp-0.60( t +0.96)]. The growth performance index (ϕ) of male and female was estimated as 4.33. The life span of male estimated using the equation tmax = 3/K is 3.66 years while the same of female is 5 years. The lengths attained by males following VBGF equation at the end of I, II, and III years were estimated at 91.51mm, 130.16 mm and 147.19 mm respectively. The lengths of females at the end of I, II, III, IV and V years were estimated at 87.19 mm, 132.61 mm, 157.62 mm, 171.39 mm and 178.98 mm respectively. Results of the length converted cohort analysis revealed that prawns in the length groups 50-60 mm and above were vulnerable to exploitation. Heavy exploitation of the length class 80-90 mm was discernible in the fishery.