Sexual Maturity, Reproductive Pattern and Spawning Female Population of the Blue Swimming Crab, Portunus pelagicus (Brachyura: Portunidae) in East Lampung Coastal Waters, Indonesia

Little is known about the biology of the blue swimming crab, Portunus pelagicus in east Lampung coastal waters, Indonesia; despite in fishery point of view this species has valuable contribution to the country. We examined the gonad development and the occurrence of ovigerous females for determining the mean size at sexual maturity, reproductive pattern and spawning female population of the crab in East Lampung coastal waters. The mean size of males and females reached sexual maturity (Lm₅₀) at 98-mm and 103-mm carapace width (CW), respectively. Reproductive pattern was partially spawners, seasonal-continuous throughout in the year with the peak spawning and breeding in April to June and October to November. Most female at the size >111-mm CW showed double breeding in a season. The relative percentage of all ovigerous females below the size of Lm₅₀ was considerably low (±2%), spawning female population at 103-170.9-mm CW size range and the ratio of ovigerous to adult females above the average value found in 116-165.9-mm CW size range. Using 115-mm CW as minimum legal size would conserve ±21.38% spawning female as breeding population.