Distribution of Bigeye Tuna in the Indian Ocean as Seen from Tuna Longline Catches.

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

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Fuzzy logic analyses for the spawner-recruitment relationship of bigeye tuna (Thunnus obesus) in the Indian Ocean incorporating the environmental regime shift

Ecological Modelling ◽

10.1016/j.ecolmodel.2005.11.049 ◽

2007 ◽

Vol 203 (1-2) ◽

pp. 132-140 ◽

Cited By ~ 2

Author(s):

Tom Nishida ◽

Ding-Geng Chen ◽

Masahiko Mohri

Keyword(s):

Fuzzy Logic ◽

Indian Ocean ◽

Regime Shift ◽

Bigeye Tuna ◽

Environmental Regime ◽

Thunnus Obesus ◽

The Indian Ocean ◽

Relationship Of

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KOMPOSISI UKURAN, PERBANDINGAN JENIS KELAMIN, DAN TINGKAT KEMATANGAN GONAD IKAN TODAK BERPARUH PENDEK (Tetrapturus angustirostris) DI SAMUDERAHINDIA

BAWAL Widya Riset Perikanan Tangkap ◽

10.15578/bawal.3.2.2010.123-128 ◽

2017 ◽

Vol 3 (2) ◽

pp. 123

Author(s):

Dian Novianto ◽

Budi Nugraha ◽

Andi Bahtiar

Keyword(s):

Indian Ocean ◽

Sex Ratio ◽

Size Composition ◽

Maturity Stage ◽

Chi Square ◽

Male And Female ◽

Level Ii ◽

Chi Square Test ◽

The Indian Ocean ◽

Tuna Longline

Ikan todak berparuh pendek atau ikan tumbuk atau shortbill spearfish (Tetrapturus angustirostris) merupakan salah satu hasil tangkapan sampingan rawai tuna. Informasi mengenai ikan todak berparuh pendek seperti komposisi ukuran, perbandingan kelamin, dan tingkat kematangan gonadsangat terbatas. Tulisan ini bertujuan untuk menyajikan data dan informasi mengenai aspek biologi ikan todak berparuh pendek yang merupakan hasil tangkapan sampingan dari rawai tuna yang beroperasi di Samudera Hindia. Penelitian ini dilakukan pada bulan September sampai Desember 2008 di perairan Samudera Hindia. Hasil penelitian menunjukan bahwa ikan todak berparuh pendek memiliki kisaran panjang tubuh 135-175 cmLJFL dan modus pada kisaran 155-165 cmLJFL.Perbandingan jenis kelamin ikan jantan dan betina 1:13,5, berdasarkan atas hasil uji chi-square menunjukan bahwa rasio ikan jantan dan betina pada periode penelitian ini tidak seimbang. Pada bulan September ikan todak berparuh pendek betina didominansi oleh tingkat kematangan gonad IIsebesar 66,7%, bulan Oktober oleh tingkat kematangan gonad V sebesar 46,2%, bulan Nopember oleh tingkat kematangan gonad II sebesar 53,3%, sedangkan pada bulan Desember oleh tingkat kematangan gonad III sebesar 42,9%. Pada bulan Nopember sampai Desember terlihat bahwa tingkat kematangan gonad V mulai berkurang, hal ini menunjukan bahwa pada bulan Nopember sampai Desember diduga banyak ikan todak berparuh pendek betina yang sudah memijah. Shortbill Spearfish (Tetrapturus angustirostris) is one of bycatch of tuna longline. Information about shortbill spearfish on the size composition, sex ratio, and maturity stage is still very limited. The objective this paper is to present the data and information about shortbill spearfish which is a bycatch of tuna longline that operated in the Indian Ocean. Research was conducted during September until December 2008 in Indian Ocean. The results showed that the shortbill spearfish have body length about 135-175 cmLJFL and modes in 155-165 cmLJFL. Sex ratio of the male and female was 1:13.5. Based on chi-square test showed that the ratio of male and female in the period of the study was not balanced. In September, the female stage maturity was dominated by level II of 66.7%, October by level V of 46.2%, November by level II of 53.3%, and December by level III of 42.9%. During November until December showed that the maturity stage of level V was decreased, this shows that in this time the female of shortbill spearfish was spawned.

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Bycatch and discards by Taiwanese large-scale tuna longline fleets in the Indian Ocean

Fisheries Research ◽

10.1016/j.fishres.2010.08.005 ◽

2010 ◽

Vol 106 (3) ◽

pp. 261-270 ◽

Cited By ~ 39

Author(s):

Hsiang-Wen Huang ◽

Kwang-Ming Liu

Keyword(s):

Indian Ocean ◽

Large Scale ◽

The Indian Ocean ◽

Tuna Longline

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COMPARISON OF INDONESIAN TUNA LONGLINE FISHING PERFORMANCE WITHIN AND OUTSIDE INDONESIA EXCLUSIVE ECONOMIC ZONE (EEZ)

Indonesian Fisheries Research Journal ◽

10.15578/ifrj.23.1.2017.1-6 ◽

2017 ◽

Vol 23 (1) ◽

pp. 1

Author(s):

Bram Setyadji ◽

Irwan Jatmiko

Keyword(s):

Indian Ocean ◽

Bluefin Tuna ◽

T Test ◽

Exclusive Economic Zone ◽

Southern Bluefin Tuna ◽

The Indian Ocean ◽

The Mean ◽

Economic Zone ◽

Tuna Longline ◽

High Seas

Indonesian tuna longline fleets have been fishing in the Exclusive Economic Zone (EEZ) and high seas of the Indian Ocean for quite some time. However, effort has never been made to separate catch from the EEZ and the high seas as it important for fisheries management. A total of 2,430 set-by-set longline fishing data had been collected by scientific observers based in the Research Institute of Tuna Fishery in Bali since August 2005 to December 2014 on which present analysis was made. The research aims to compare between trend of tuna catch of the EEZ and of the high seas of Indian Ocean. The results show that the mean hook rate of both catches of big eye tuna (BET) and southern Bluefin tuna (SBT) caught in the high seas was significantly higher than that the EEZ (two sample t-test, p<0.05), while for yellow fin tuna (YFT) it was in the opposite direction (two sample t-test, p<0.05). As for albacore (ALB), the mean hook rate value was statistically similar in both fishing grounds (two sample t-test, p>0.05).

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