Freshwater Fish Diversity in Thailand and the Challenges on Its Prosperity Due To River Damming

Abstract

Thailand is among the countries that ranked top in freshwater fish diversity, of which 843 freshwater fish species, including 13 elasmobranch fishes, have been officially recorded. Presently, the integrity of freshwater fish community is threatened by many stressors from human activities, in particular the river damming. In this paper, we illustrate the impacts to freshwater fish diversity by various dam types in Thailand. The major serious impact of river damming is the blockage of fish migratory routes, both for the species that migrate within river system and migrate between the river and the sea. So far, there is no any fish passage that reveals the effective performance because it is difficult to deal with the many fish species, with various modes of swimming and water flow preferences, in a single designed fish passage. The consequent results are the extirpation of the migratory species and, then, changes in fish community structures. The mitigation measure of opening the sluice gates for a certain period is recommended. This measure is beneficial for the fish migrations both for the dams in the middle portion and lower portion, i.e., brackish area, of the river, which allows the fish to complete their life cycles and can manipulate the fish assemblage patterns.

Sustainable fisheries management through reliable restocking and stock enhancement evaluation with environmental DNA

“…In addition, a third of global freshwater fish populations are threatened with extinction 2 , with 16 species already having been declared extinct in the year 2020 alone. Thailand is regarded internationally as one of the countries with high diversity of freshwater fish species; as many as 850 species have been reported, and about 10% of the world’s freshwater fish species live in Thailand 3 . Populations of freshwater fish are declining rapidly, and much of that decline is driven by human activities.…”