This study assessed bycatch composition and some factors affected assemblage from blue swimming crab fisheries in semi-enclosed Pattani Bay and offshore area, the Gulf of Thailand. Samples were collected from May 2013 to September 2014 by using crab gill net. One hundred seventy four of bycatches were found within proportion of 52.2% in the bay and 49.5% from offshore. Moreover, discarded species from the bay and offshore were 26.3% and 47.1%, respectively. The most dominant species in the bay was horse shoe crab (Carcinoscorpius rotundicauda) while offshore was scaly whipray (Himantura imbricate). Abundance of bycatch in the bay was affected both by habitat (P<0.005) and season (P<0.001) while abundance from offshore was affected only by season (P<0.05). Species richness of bycatch both in the bay and offshore were influenced significantly by season (P<0.001 and P<0.005, respectively). The most abundance bycatch in the bay was found in the inner bay while at 15m depth for offshore. The result of nMDS ordination indicated a separation of three major groups of assemblage in the bay; inner, middle and outer bay but there was no obvious segregation from offshore.
This study determined the distribution and ontogenetic habitat shifts of Portunus pelagicus in coastal habitats in Thailand. Samples were collected by gill nets and traps, at six study sites during May 2013 and September 2014. It was found that, in the bay, the catches from both gears were significantly influenced by depth ( and ) but not by season (). For offshore, the catch was significantly influenced by season () but not by depth (). The catches of berried females in the bay and in the offshore area were not influenced either by depth, or by season (). In addition, it is proven by this study that a habitat shift during ontogeny occurs as young crabs or small-sized crabs inhabit shallow waters, and migrate to deeper water when they grow larger.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.