Figure 3. The dominant freshwater fishes in NHW, Sakon Nakhon Province, Thailand: Puntius brevis (1) and Cyclocheilichthys apogon (2). Among all species, the golden little barb (Puntius brevis) and the beardless barb (Cyclocheilichthys apogon) (Figure 3) were the most common. The beardless barb fishes were collected in all sites except at Don Sawan during March 2011. The presence of these fishes implied that their food sources were readily available. It also meant that they were adapted to the environmental conditions of the wetland. They are economically important species and are used for making salted and fermented fish, or are sold as ornamental fish, thus generating income for local people engaged in small scale fisheries businesses. The study revealed that the highest species richness of freshwater fish was in Don Chaing Ban (littoral zone) with 21 species. The variety of aquatic plants that serve as habitats and food for the freshwater fish may account for the species richness and conservation of fish species. Twelve species of fish were identified in Don Sawan, which implies that there might be less ecosystem support for a richer variety species. However, as this zone is in the open water where there is an abundance of plankton, freshwater fish in this site is likely bigger in size (length and weight) than in Don Chaing Ban. Table 2. Index of Similarity (of Freshwater Fish in Two Study Sites in Nong Han Wetland, Sakon Nakhon Province, Thailand: Don Chaing Ban (S1) and Don Sawan (S2), March-April 2011. Variables March April No. of species in site 1 (S1) 21 15 No. of species in site 2 (S2) 12 12 No. of same species (C) 10 9 S1+S2 = (A) 33 27 2C = (B) 20 18 (B)/(A) = (D) 0.61 0.67 Index of Similarity (IS) = (D) x 100 60.61 66.67 30 THE ASIA REGIONAL FORUM ON BIODIVERSITY Index of similarity (IS) of freshwater fish in NHW was also studied to examine the percentage of IS between the two sampling sites. The study found that the IS has higher value (66.67) during the collection in April 2011 (Table 2). This implies the even distribution of fish species and the low rate of movement in search of food since the fish will normally be laying eggs around the middle of May each year. As a result, the Department of Fisheries declared 16 May-15 September each year as the closed season for catching fisheries in Thailand. There is less species richness in this study compared with others that have listed more than 40 species of freshwater fish observed in NHW. This implied that fishery resources are declining probably due to over exploitation and habitat degradation. Conclusion Nong Han Wetland is a complex ecosystem with rich aquatic flora and fauna. The wetland plays an important role in ensuring the supply of fresh water for human use and consumption while also serving as habitat for many organisms. NHW was studied to determine species composition of freshwater fish in shallow and open waters from March to April 2011. Gill nets were used for the collection of species. The study revealed prevalence of economically important and rare indigenous fish species. Because of rich species composition recorded at the littoral zone, biodiversity conservation efforts can be initiated in that area using dominant fish species. The Nong Han Wetland is likely to face environmental problems such as habitat degradation and deterioration of environmental quality from both anthropogenic disturbances and natural impacts, such as flood and drought. These habitats must be protected, coupled with increase environmental awareness and the cooperation of local communities. Moreover, the business sector, particularly businesses engaged in the fisheries industry, can also be tapped to support the conservation of fisheries biodiversity through their Corporate Social Responsibility programmes.
In Celebration of His Majesty the King of Thailand’s 84th Birthday Anniversary
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