Age and growth in two marine portunid crabs, Portunus (Portunus) sanguinolentus (Herbst) and Portunus (Portunus) pelagicus (Linnaeus) along the southwest coast of India

Abstract

Age and growth of two marine protunid crabs, Portunus (Portunus) sanguinolentus and P. (P.) pelagicus was investigated based on the data collected from the commercial catches landed at Mangalore, Malpe and Karwar, three major fish landing centres in Karnataka state, along the southwest coast of India during 1992-'94. The size frequency analysis indicated that the growth rate was high and more or less uniform in juveniles, while the adults showed relatively low rate of growth and marked variation in males and females. In P. (P.) sanguinolentus, the mean monthly growth rates were 10.3 m and 8.8 mm and attained a carapace width of 124.1 and 112.5 mm by males and females respectively on completion of one year. In P. (P.) pelagicus, the average growth rates were 11.0 and 9.6 mm and attained a size of 145.2 and 132.5 mm by males and females respectively, at the end of one year. The von Bertalanffy's growth parameters, L_, K and to were 195 mm, 0.99 yr1 and -0.0132 yr for males and 188 mm, 0.82 yr1 and -0.0975 yr for females. In P. (P.) pelagicus, the growth parameters were 211 mm,. 1.14 yr 1 and -0.0194 yr for males and 204 mm, 0.97 yr1 and -0.0691 yr for females.