PERTUMBUHAN DAN MORTALITAS IKAN TUNA MATA BESAR (Thunnus obesus) DI SAMUDERA HINDIA YANG DIDARATKAN DI PELABUHAN BENOA, DENPASAR, BALI
Authors: Kurniawati Erika , Ghofar Abdul , Saputra Suradi Wijaya , Nugraha Budi 
Published: September 2020

ABSTRAK Tuna mata besar (Thunnus obesus) di Samudera Hindia menjadi salah satu target utama penangkapan. Berdasarkan pemanfaatan tersebut, perlu dilakukan penelitian mengenai parameter populasi tuna mata besar. Penelitian ini bertujuan untuk mengetahui aspek pertumbuhan, ukuran pertama kali tertangkap, parameter populasi, laju mortalitas, laju eksploitasi dan pola rekrutmen. Jumlah sampel tuna mata besar sebanyak 648 ekor diambil dari 21 armada rawai tuna (longline) yang melakukan bongkar selama penelitian. Data panjang tahun 2013-2014 diperoleh dari Loka Penelitian Perikanan Tuna Bali. Penelitian ini dilakukan bulan April-Mei 2016 di Pelabuhan Benoa, Denpasar, Bali. Analisis data menggunakan Model Von Bertalanffy Growth Function dengan software FISAT II. Hasil penelitian menunjukkan pola pertumbuhan bersifat allometrik negatif. Faktor kondisi diperoleh sebesar 1,02-1,27. Ukuran pertama kali tertangkap (L50%) sebesar 126,54 cmFL. Persamaan pertumbuhan Von Bertalanffy Growth Function (VBGF) diperoleh Lt=199,5(1 - e 0,22 (t+0,451)), dengan nilai K= 0,22/tahun, nilai t0= -0,451 tahun dan L∞ = 199,5 cmFL. Laju mortalitas penangkapan (F) = 0,51/tahun, lebih besar daripada mortalitas alami (M) = 0,40/tahun, berarti kematian tuna mata besar lebih banyak disebabkan karena faktor eksploitasi/penangkapan. Laju eksploitasi (E)= 0,56 mengindikasikan tuna mata besar yang tertangkap oleh armada rawai tuna (longline) di Samudera Hindia dalam kondisi fully exploited (padat tangkap).Kata Kunci : Ikan tuna mata besar; aspek biologi; umur; pertumbuhan; mortalitas; laju eksploitasi; rekrutmen; Samudera Hindia  ABSTRACT Bigeye tuna (Thunnus obesus) in the Indian Ocean became one of the main targets of arrest. Based on utilization, research is needed on bigeye tuna population parameters. This study aims to determine of growth, size at the first caught, population parameters, mortality rate, exploitation rate and recruitment patterns. Number samples of bigeye tuna were taken from 648 fishes by 21 tuna longline fleets which was unloading during this study. Length data of 2013-2014 were obtained from Research Institute for Tuna Fisheries, Bali. This research was conducted April-May 2016 in Benoa Harbour, Denpasar, Bali. Data analysis used the Von Bertalanffy Growth Function Model with FISAT II software. The results showed negative allometric growth patterns. The condition factor was obtained for 1.02 to 1.27. The length at first caught (L50%) amounted to 126.54 cmFL. VBGF growth equation was obtained Lt=199.5(1 - e 0.22 (t + 0.451)), with the value K=0,22/year, t0= -0,451/year and L∞= 199,5 cmFL. The fishing mortality rate (F)= 0.51/year, it was bigger than the natural mortality (M)= 0.40/year, means that mostly mortality of bigeye tuna was caused by the exploitation / fishing factor. The exploitation rate (E)= 0.56, indicated that bigeye tuna were caught by tuna longline fleets in the Indian Ocean on fully exploited.Keywords:Bigeye tuna; biology aspect; age; growth; mortality; exploitation rate; recruitment; Indian Ocean