The Utility of DNA Barcoding for the Species Identification of Larval Fish in the Lower Ing River, Thailand

Abstract

The species identification of larval fish is very important for sustainable fishery resource management. However, identification based on morphological characters is very difficult, complex and error-prone. DNA barcoding with the sequence of cytochrome c oxidase I (COI) gene was used to identify larval fish species from 10 stations in the tributaries of the lower Ing River. One hundred and six samples were collected between May 2016 and April 2017. The average length of the COI nucleotide sequences was approximately 640 bp. A total of 99 nucleotide sequences were identified in 35 species, 31 genera, 19 families and 9 orders, with 97-100% identity with entries in both the GenBank and BOLD databases. The genetic distance within species ranged from 0.000 to 0.004. However, seven samples were identified at only the genus level because their sequences had not been reported in any databases. Based on IUCN conservation status, most species were classified as least concern (77.14%). Approximately 69.23% of all species were related to human uses in fisheries, aquaculture or aquariums, whereas 30.77% of species were not assessed. Trichopsis vittata (family Osphronemidae) (90%) had the most frequency of occurrence, followed by Oryzias minutillus (family Adrianichthyidae) (70%) and Trichopodus trichopterus (family Osphronemidae) (70%).