ISSN: 2577-4050
Authors: Islam MS*, Mondal A, Khan Y and Kader A
The mud crab (Scylla olivacea) is one of the important exported commodities and playing a vital role in the economy of Bangladesh. The harvesting and exportation of crab increasing day by day without knowing the abundance and biological traits particularly of female mud crab. The present study was taken to assess the abundance, size distribution, population distribution regarding physiochemical properties and reproductive biology of female mud crab from selected Sundarbans mangrove forest in the southwest Bangladesh. The year-round female mud crab samples were taken from different stations of Koyra of Khulna and Symnagor of Satkhira district. The results showed that female crab harvested almost in similar pattern from both sampling areas. The average abundance estimated as 4.9±1.4 (kg/day/collector) with the average number of 15.5 ± 2.9/day/collector. The assessed samples was 33% female and 15% hijra (immature female) reported from Koyra, Khulna while only 10% female and 44% hijra reported from Symnagor, Satkhira. The water parameters like salinity, pH, temperature, total dissolve solids, dissolve oxygen and conductivity were measured in each sampling months from different sampling stations and were not significant difference (P>0.05) between two districts. In addition, there is no significant relationship between abundance and recruitment of female crabs with the major physiochemical parameters. However, hijra crab was higher in number during winter in Symnagor, Satkhira. In case of size-class distribution, it is noticed that most female species (35%) were belong to the size group of 80-89mm internal carapace width (ICW). Almost 90% female crabs were belonging to the size <90 mm ICW. Ovarian development stages were categorized into five stages like I) immature ovary, II) under develop, III) early develop, IV) late develop and V) mature stage according to their internal observation of ovaries. There were only 14% individuals belongs to the mature ovarian development stage. However, 56% sampled individuals were mature considering the formation of vitellogenesis (ovarian development stage III-V). The 50% of female individuals get mature at the size of 84.63 mm ICW. The present findings will be act as base line to propose suitable management strategies of the resources in the coastal area of Bangladesh.
Keywords: Scylla olivacea; Abundance; Size-Class Distribution; Ovarian Development Stages; Water Parameters; Female Maturity Size
