Male reproductive biology of mud crab Scylla olivacea in a tropical mangrove swamps

Abstract

Mud crabs of the genus Scylla are commercially important and conspicuous crustaceans provide basic source of income for coastal fishing communities throughout the Indo-Pacific region. The reproductive traits and size at sexual maturity of the male mud crab Scylla olivacea were investigated in Pak Phanang mangrove swamps, Thailand. Samples were taken seven times from the local middlemen mud crab traders during June 2006 to January 2008. Gonad development was determined based on histological appearance that was classified into three stages: (1) Immature (Spermatogonia) (2) Maturing (Spermatocytes) and (3) Mature (Spermatids and Spermatozoa). Among the sample population, the highest 56% was under gonad development stage I, whereas mature stage III was only 18%. The size at first maturity was estimated by the external allometric growth and histological observation of gonad. The size at which 50% of individuals attain sexual maturity was estimated by the two mathematical models such as probit analysis and logistic curve. The mean size at first sexual maturity and 50% maturation of male S. olivacea were 87 and 103 mm Internal Carapace Width (ICW) which revealed that 80% of individuals were immature. The present result suggested that the minimum legal size of male mud crab capture should be >100 mm ICW. © 2012 Academic Journals Inc.