What is it about?
Sharks and rays are highly diverse in Thai waters, but identifying them accurately can be difficult, particularly when closely related species look alike, and taxonomic expertise is limited. We examined two commonly used DNA barcode markers, COI and ND2, together with morphological identification, using elasmobranch samples collected from the Gulf of Thailand and the Andaman Sea. The study included 153 successfully amplified samples representing 28 shark species and 32 batoid species. DNA barcoding successfully supported the identification of many species, but it also revealed important limitations. Missing reference sequences, outdated species names, misidentified database records, cryptic similarity among species, and disagreement between morphology and DNA could all complicate identification.
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Why is it important?
DNA barcoding can greatly improve biodiversity assessment, particularly where specialist taxonomists are scarce. However, a DNA sequence match is not automatically a correct species identification. Our findings show that reliable identification requires interpreting DNA evidence alongside specimen morphology, geographic information, current taxonomy, and well-curated reference collections. This is especially important for sharks and rays, for which taxonomic revisions are ongoing, and some rare species remain poorly represented in public genetic databases. This work contributes to SDG 14: Life Below Water by strengthening the scientific basis for marine biodiversity assessment, conservation, and the sustainable management of sharks and rays.
Perspectives
DNA barcoding is powerful, but the quality of an identification depends on the quality of the reference behind it. Rather than replacing traditional taxonomy, molecular tools and morphological expertise should work together. Building verified local reference collections will improve biodiversity monitoring and provide a stronger foundation for conservation, fisheries management, and authentication of products derived from threatened sharks and rays. By improving the reliability of shark and ray identification, this study supports evidence-based biodiversity monitoring and fisheries management, aligning particularly with SDG 14 (Life Below Water).
Wansuk Senanan
Burapha University
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This page is a summary of: DNA barcoding for elasmobranch diversity assessment in Thailand: Its advantages and limitations, PLOS One, October 2025, PLOS,
DOI: 10.1371/journal.pone.0334640.
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