Temporal variation in community structure of Dragnet (Pukat Tarik) fishery in relation to ecological variables in an inshore area of Sarawak, Malaysia

Abstract

Inshore waters are crucial for fisheries since such areas show a wide range of variations in ecology, mostly considered to shape biotic ecosystems. Despite major fishing activities off Bintulu coast located along the South China Sea operating in the inshore areas and significantly contributing to local fisheries’ economy by Pukat Tarik (dragnet), temporal exchange of fisheries composition in terms of ecological parameters has been little studied. Therefore, temporal changes in pull net fisheries composition and assemblages in relation to the ecological parameters in the inshore waters of Bintulu coast, Sarawak, were observed from May 2016 to April 2017. A total of 63 species belonging to 15 orders of 40 families were recorded, and 11 species found ubiquitous. Species diversity (H´) was recorded higher (2.61) in northeast monsoon, and lower (0.51) in inter-monsoon season, yet the species richness and diversity did not show temporal differences (p>0.05). Among the species Kurtus indicus was recorded the most abundant (58% of the total catch) followed by Photopectoralis bindus (15%) and Opisthopterus tardoore (7%); and the species abundance showed significant temporal differences (p<0.05). However, temperature, salinity, pH, dissolved oxygen (DO) and rainfall showed classical temporal differences (p<0.05), and no significant difference was found in chlorophyll a and water nutrients. ANOSIM indicated that the significant difference of assemblages among season was more apparent than within season (Global R=0.65, p<0.001). The canonical correspondence analysis indicated total suspended solids, dissolved oxygen (DO), transparency, rainfall and salinity as the most important ecological factors affecting fish assemblage structure. The inshore fisheries of Bintulu coast were found immensely rich and profoundly related to ecological factors, which will eventually help manage this fishery resource in the future in tropical coastal waters of the South China Sea.

Keywords

• pull net
• pelagic fisheries
• ecological factors
• bintulu fishing industry