Observations on the effect of natural diets on ovarian rematuration in blue swimming crab Portunus pelagicus (Linnaeus, 1758)

Abstract

This study was carried out to evaluate the effect of natural diets on ovarian maturation in the blue swimming crab Portunus pelagicus. A total of 25 female crabs in the spent condition were collected from Johor, Peninsular Malaysia. Five animals were used for histological examination of the ovary and the rest twenty were used for the feeding experiment. Four dietary groups each comprising 5 crabs, were fed with four different diets viz., Loligo sp., blood cockle, Anadara sp., fish, Decapterus sp. and polychaete, Neries sp., @10% of body weight daily. Throughout the experimental period, the number of days taken by the females to remature and become ovigerous again as well as the number of larvae produced in each treatment was recorded. The results showed that crabs fed with polychaetes rematured and became oveigerous faster (14.4±7.7 days), followed by crabs fed with blood cockle (14.8± 1.12 days), fish (21.2±11.2 days) and squid (26±12.2 days). However in contrast, squid was found to be the best diet in terms of producing more number of larvae (329240±193390 larvae), compared to crabs fed with scad fish (323500±118096 larvae), followed by cockle (263444±153,021 larvae) and polychaete (256520±160677 larvae).