Abstrak
The gecko shark is one of the fishery commodities caught by fishermen in the Tanah Kuning Waters, Bulungan Regency, North Kalimantan. The purpose of this study was to identify the species and molecular characteristics of the gecko shark using the mitochondrial COl gene-based DNA barcoding method. The study was conducted from December 2024 to March 2025. The method used was random sampling, with three gecko shark specimens taken from the Tanah Kuning waters using a trawl. Identification was carried out through two approaches: (1) morphological analysis using morphometric such as total length, head length, and fin shape; and (2) molecular analysis with stages of DNA extraction, DNA purity measurement, and mitochondrial COl gene amplification with PCR, electrophoresis, and DNA sequencing. Genetic identity validation was carried out using BLAST analysis and genetic distance calculations using the Tamura 3-Parameter model. The results of the nucleotide base sequence validation through the NCBI website showed that the sample had 100% similarity to Hemigaleus microstoma from Malaysia. Genetic and phylogenetic distance analysis showed that the sample from North Kalimantan was closely related to the samples from Bali and India. Based on the IUCN, Hemigaleus microstoma was categorized as a vulnerable species, so the results of this study confirmed the need for conservation efforts for this species in the study area.