Elasmobranchs play an important role in the functioning of marine ecosystems and top-down control in food webs. However, overexploitation threatens elasmobranch populations worldwide. Indonesia is currently the leading elasmobranch fishing nation, yet elasmobranch management in Indonesia is challenging because of the paucity of data on elasmobranch fisheries, especially at a species level. This study examined the elasmobranch fisheries of the Bali Strait by describing the species, sex and size composition of the elasmobranch catch landed at a major port in Eastern Java, Indonesia. Data were collected between August 2017 and March 2018 in Muncar. Elasmobranchs were identified to species level and sexed. The disc width and length of 301 rays and the precaudal length and fork length of 1657 sharks were measured. In all, 53 species were identified, many of which are at conservation risk, including species with national and international protection. Vulnerability to fishing gear varied across sex and size of each species, with immature individuals dominating the catch of most species. The findings emphasise the need for improved management of elasmobranchs in Indonesia and could help identify priorities or form strategies. Additional regional and fisheries-specific research is recommended to develop efficient and locally adapted management strategies.

Tuna albakora (Thunnus alalunga) merupakan salah satu jenis tuna yang ditemukan di perairan Indonesia. Penelitian terhadap aspek dinamika popukasi tuna albakora masih jarang dan perlu dilakukan pengkajian dalam upaya pengendalian stok. Tujuan penelitian ini adalah untuk mengetahui hubungan panjang berat dan aspek dinamika populasi yang meliputi pendugaan kelompok umur, parameter pertumbuhan (L”, K, dan to), laju mortalitas, laju eksploitasi, rekrutmen, analisa yield per recruit (Y/R) dan biomassa per recruit (B/R) pada ikan tuna albakora (T. alalunga). Penelitian dilaksanakan di Pelabuhan Perikanan Nusantara (PPN) Prigi, Kabupaten Trenggalek, Jawa Timur pada bulan Agustus-Desember 2016. Metode yang digunakan adalah metode deskriptif analitik dengan 2.702 sampel ikan. Hasil penelitian menunjukkan bahwa pertumbuhan ikan bersifat allometri negatif dengan nilai b<3. Parameter pertumbuhan Von Bertalanffy didapatkan hasil L” = 118,3 cm FL dan K = 0,51/year. Nilai to diketahui dengan menggunakan persamaan Pauly (1984) dihasilkan to = -0,219 tahun. Nilai Lc dan Lm masing-masing sebesar 101,61 cm FL dan 90 cm FL. Nilai laju mortalitas total (Z) tuna albakora = 1,81, laju mortalitas alami (M) = 0,8 laju mortalitas penangkapan (F)= 1,01, laju eksploitasi (E) = 0,56 atau 56%, nilai yield per recruit (Y/R) = 0,029 per tahun dan biomassa per recruit (B/R) = 0,349 per tahun.