Length Distribution and Abundance of Sharks and Relationship with Temperature in the Bali Strait Waters

This study aimed to analyze the composition, size distribution, sex ratios, and the influence of sea surface temperature (SST) on shark by-catch in the Bali Strait. Data were collected at Brak Muncar Fish Landing Port, Banyuwangi, from March 2023 to February 2024, using a census method for three dominant species: Alopias pelagicus, Carcharhinus melanopterus, and Atelomycterus marmoratus. Species identification, total length (TL) measurements, and sex determination followed scientific protocols, while SST data were processed using IDW interpolation in QGIS. A simple linear regression analysis tested the relationship between SST and catch abundance. A total of 299 shark individuals were recorded, dominated by A. marmoratus (140 individuals) and C. melanopterus (131 individuals). Most catches comprised juveniles, particularly C. melanopterus (45–56.6cm) and A. pelagicus (137.8–172.7cm), indicating exploitation of immature populations. A balanced sex ratio (1:1) was observed across all species. SST significantly influenced C. melanopterus catches (R = 0.650), moderately affected A. pelagicus (R = 0.496), and had negligible impact on A. marmoratus (R = 0.085) due to its dependency on coral reef habitats. Policy implications emphasize the need for strict by-catch reduction regulations, temporary no-catch zones in breeding areas, and conservation policy harmonization aligned with IUCN/CITES statuses. Recommendations include training fishers in selective techniques, establishing community-based monitoring systems, and integrating ecological data into science-based catch quotas. Further studies should focus on long-term monitoring, genetic population analyses, and interdisciplinary approaches to support sustainable shark fisheries in Indonesia.