DISTRIBUSI UKURAN PANJANG DAN HUBUNGAN PANJANG BERAT IKAN TUNA SIRIP KUNING (Thunnus albacares, Bonnaterre, 1788) HASIL TANGKAPAN PANCING ULUR YANG DIDARATKAN DI TPI PONDOKDADAP, SENDANGBIRU

Ikan Tuna Madhidihang (Thunnus albacares) merupakan salah satu jenis ikan ekonomis penting di dunia dan komoditas ekspor perikanan adal Indonesia. Pemanfaatan sumber daya perikanan umumnya milik bersama (common property) artinya upaya pemanfaatan dapat dilakukan secara bersama dalam waktu yang bersamaan oleh pelaku usaha perikanan (open acces). Semakin meningkatnya upaya pemanfaatan yang dilakukan dan banyaknya hasil tangkapan ikan tuna dibawah ukuran pertama kali matang gonad mengakibatkan terganggunya proses rekruitmen ikan-ikan muda di alam. Untuk mendukung pengambilan keputusan yang tepat dalam upaya pengelolaan perikanan yang berkelanjutan, maka ketersediaan data dan informasi yang terukur mutlak diperlukan untuk mengetahui status sumber daya perikanan tuna dewasa ini. Tujuan dari penelitian ini adalah untuk mengetahui (1) distribusi panjang ikan dan (2) hubungan panjang berat ikan tuna madhidihang di wilayah perairan selatan Jawa Timur (Sendang Biru).  Pengambilan data dilakukan di Tempat Pelelangan Ikan (TPI) Pelabuhan Pondokdadap Sendangbiru Malang, pada Bulan Agustus – Oktober 2022.  Sampel ikan tuna madhidihang yang didaratkan kemudian diukur panjang dan beratnya, dianalisis dengan menggunakan regresi linier untuk melihat hubungan antara panjang dan berat ikan.  Ada 347 ekor ikan madhidihang yang berhasil diukur panjang cagak dan beratnya pada bulan Agustus hingga Oktober 2022. Berdasarkan data yang telah diolah, rata-rata panjang cagak sekitar 109 cm, panjang cagak dominan antara 136 – 145 cm dengan panjang maksimal 195 cm dan minimal 86 cm.  Berdasarkan data Fish Base ukuran ikan pertama kali matang gonad atau Length at first maturity (Lm) tuna sirip kuning berada pada ukuran 103,3 cm. Hasil penelitian menunjukkan bahwa 55%  hasil tangkapan tuna sirip kuning nelayan Sendangbiru sudah layak tangkap, dan 45% belum layak tangkap.  Hasil analisis hubungan panjang dan berat ikan tuna madhidihang di lokasi penelitian memperlihatkan pertumbuhan bersifat alometrik negatif dimana pertumbuhan panjang lebih dominan daripada pertumbuhan berat ikan.   Yellowfin Tuna (Thunnus albacares) is one of the economically important fish species in the world and an Indonesian fishery export commodity. Utilization of fishery resources is generally shared property (common property) meaning that efforts to exploit can be carried out jointly at the same time by fishery business actors (open access). Increasing utilization efforts are being made and the large number of tuna catches below the size at first maturity has disrupted the recruitment process for young fish in nature. To support the right decision making in efforts to manage sustainable fisheries, the availability of measurable data and information are absolutely necessary to determine the current status of tuna fishery resources. The aims of this study were to determine (1) the distribution of fish length and (2) the relationship between the length and weight of yellowfin tuna in the southern waters of East Java (Sendang Biru). Data collection was carried out at the Fish Auction Place (TPI) Pondokdadap Port Sendangbiru Malang, from August to October 2022. The yellowfin tuna samples that were landed were then measured for length and weight, then analyzed using linear regression, so that a relationship between the length and weight of the fish could be seen. The number of yellowfin tuna or yellowfin tuna whose fork length and weight were successfully measured from August to October 2022 was 347 individual fish. Based on the data that had been processed, the dominant fork length of yellowfin tuna was between 136 – 145 cm with a maximum length of 195 cm and a minimum of 86 cm, and an average fork length of around 109 cm. Based on Fish Base data, the length at first maturity (Lm) of yellowfin tuna was 103.3 cm. This showed that the catch of yellow fin tuna by Sendangbiru fishermen had a percentage of 55% that was suitable for catching, while those that were not yet worth catching had a percentage of 45%. Fish length and weight data can be used to see the morphometric condition of a fish species. From the results of the analysis of the relationship between length and weight of yellowfin tuna at the study site, it was known that growth was negative allometric where length growth was more dominant than fish weight growth.