scholarly journals BEBERAPA PARAMETER POPULASI IKAN PEDANG (Xiphias gladius) DI SAMUDERA HINDIA BAGIAN TIMUR

2017 ◽  
Vol 8 (2) ◽  
pp. 117
Author(s):  
Bram Setyadji ◽  
I Wayan Arthana ◽  
I Wayan Kasa
Keyword(s):  
Indian Ocean ◽  
Stock Assessment ◽  
Total Mortality ◽  
Growth Parameter ◽  
Assessment Model ◽  
Eastern Indian Ocean ◽  
Optimum Level ◽  
Xiphias Gladius ◽  
Longline Fisheries ◽  
Tuna Longline

Komposisi hasil tangkapan ikan berparuh (Istiophoridae dan Xiphiidae) menduduki peringkat kedua terbesar setelah tuna (Thunnus sp.) pada perikanan rawai tuna. Sekitar 90% jenis ikan berparuh yang di daratkan didominasi oleh ikan pedang (Xiphias gladius), yang mana merupakan hasil tangkap sampingan dari perikanan rawai tuna, terutama di Samudera Hindia bagian timur. Meskipun dikategorikan sebagai ikan dengan nilai ekonomis tinggi, akan tetapi studi mengenai parameter populasi untuk spesies ini masih terbatas, terutama di Indonesia. Penelitian ini bertujuan untuk menduga parameter pertumbuhan, laju mortalitas dan laju ekploitasi ikan pedang berdasarkan data ukuran panjang. Model pengkajian stok menggunakan data frekuensi panjang dipilih karena ketersediaan dan kemudahan pengambilan data tersebut dibandingkan dengan metode lainnya. Penelitian ini menggunakan data pemantau ilmiah tahun 2005 sampai dengan 2014 dan data pengamatan harian pendaratan tuna dan sejenisnya tahun 2002 sampai dengan 2014 di Samudera Hindia. Hasil penelitian menunjukkan pertumbuhan ikan pedang relatif cepat, terutama pada awal masa pertumbuhan dengan nilai K = 0,12/tahun, t0 = -0,76025 tahun dan L = 302,4 cmFL. Nilai F (0,28/tahun) sedikit lebih besar daripada nilai M (0,24/tahun), yang berarti kematian ikan pedang lebih banyak disebabkan oleh penangkapan. Nilai E sebesar 0,55 mengindikasikan bahwa ikan pedang yang tertangkap oleh armada rawai tuna di Samudera Hindia berada pada kondisi optimum. Billfishes (Istiophoridae and Xiphiidae) are the second largest catch in tuna longline fisheries. About 90% of billfishes landed dominated by swordfish (Xiphias gladius) which was a by-catch from tuna longline fisheries, especially in eastern Indian Ocean. Despite of its high economic value, study on stock assessment for this species is limited, especially in Indonesia. The catch-at-size based stock assessment model was applied, to its availability and ease on collecting the data. The Objectives of this study are to estimate growth parameter, mortality rate and exploitation rate based on catch-at-size data. The primary data was obtained from scientific observer program from 2005 to 2014 and port sampling data from 2002 to 2014. The result showed that swordfish were relatively fast growth, especially on their early age (K = 0.12/year) with t0 estimated around -0.76 year and Linf about 302.4 cmLJFL. The estimated of total mortality (Z), natural mortality (M) and fishing mortality (F) from the model were 0.52/year, 0.24/year and 0.28/year respectively. The explitation rate of swordfish in the eastern Indian Ocean is on optimum level (E=0.55).

scholarly journals KOMPOSISI HASIL TANGKAPAN SAMPINGAN DAN IKAN TARGET PERIKANAN RAWAI TUNA BAGIAN TIMUR SAMUDERA HINDIA (Catch Composition of By-Catch and Target Species on Tuna Longline Fisheries in Eastern Indian Ocean)

2016 ◽  
Vol 5 (2) ◽  
pp. 119
Author(s):  
Dian Novianto ◽  
Budi Nugraha
Keyword(s):  
Indian Ocean ◽  
Eastern Indian Ocean ◽  
Target Species ◽  
Olive Ridley ◽  
Lepidochelys Olivacea ◽  
Bony Fishes ◽  
By Catch ◽  
Catch Composition ◽  
Longline Fisheries ◽  
Tuna Longline

<p>ABSTRACT<br />Tuna longline operations also capture other than tuna species are known as by-catch are caught accidentally due to the ecological linkages. This study aims to identify the species composition of by-catch and try to analyzed the interaction of non-target species with tuna species as the target species on tuna longline fishery in the eastern Indian Ocean. Surveillance was conducted on February 2013-January 2014 by following 7 commercial tuna longliners vessel with fishing operations for 226 days. The results showed there were 36 species, where the target species consists of 4 tuna species (26.11%) and 32 by-catch species consist of by-product (24.08%) and that is not utilized (discards, 49.74%). The Results of by-catch are consists of a lancetfish (Alepisaurus spp., 42.87%), pelagic stingray (Pteroplatytrygon violacea, 22.05%), escolar (Lepidocybium flavobrunneum, 10.22%) and sickle pomfret (Taractichthys steindachneri, 8.21%), while for other species consists of are billfishes (6 species), shark and rays species (10 species), bony fishes (11 species) and turtles (olive ridley).</p><p>Keywords: by-catch, tuna longline, Indian ocean</p><p>-------</p><p>ABSTRAK</p><p>Pengoperasian rawai tuna juga menangkap jenis-jenis lain selain tuna yang dikenal dengan sebutan hasil tangkap sampingan (HTS atau by-catch) yang tertangkap secara tidak sengaja dikarenakan adanya keterkaitan secara ekologi. Penelitian ini bertujuan untuk mengidentifikasi komposisi jenis hasil tangkap sampingan dan mencoba menganalisis hubungan interaksi ikan hasil tangkap sampingan dengan ikan tuna sebagai tangkapan utama (target species) pada perikanan rawai tuna di bagian timur Samudera Hindia. Pengamatan dilakukan pada bulan Februari 2013-Januari 2014 dengan mengikuti kegiatan operasi penangkapan 7 kapal rawai tuna komersial dengan selama 226 hari operasi penangkapan. Hasil penelitian menunjukkanterdapat 35 jenis ikan dan 1 jenis penyu dimana target utama terdiri dari 4 jenis ikan (26,11%) dan hasil tangkapan sampingan 31 jenis ikan dan 1 jenis penyu dimana yang dimanfaatkan (by-product) (24,08%) dan yang tidak dimanfaatkan (discards) (49,74%). Hasil tangkapan sampingan berturut-turut didominasi oleh ikan naga (Alepisaurus spp., 42,87%), pari lemer (Pteroplatytrygon violacea, 22,05%), ikan setan (Lepidocybium flavobrunneum, 10,22%) dan bawal sabit (Taractichthys steindachneri, 8,21%), selanjutnya juga tertangkap jenis paruh panjang (billfish, 6 spesies), jenis cucut dan pari (elasmobranchii, 10 spesies), jenis teleostei (bony fishes,11 spesies) dan penyu lekang (Lepidochelys olivacea).</p><p><br />Kata kunci: Hasil tangkap sampingan, rawai tuna, Samudera Hindia</p>

scholarly journals DAERAHPENANGKAPAN, LAJUPANCINGDANPARAMETERPOPULASI IKAN GINDARA (Lepidocybium flavobrunneum) DI SAMUDERA HINDIA

2016 ◽  
Vol 8 (1) ◽  
pp. 49 ◽  
Author(s):  
Andi Bahtiar ◽  
Abram Barata ◽  
Dian Novianto
Keyword(s):  
Indian Ocean ◽  
Total Mortality ◽  
Growth Parameter ◽  
Fishing Ground ◽  
Fishing Mortality ◽  
Length Frequency ◽  
Instantaneous Rate ◽  
Exploitation Rate ◽  
The Indian Ocean ◽  
Longline Fisheries

<p><strong> </strong></p><p>Ikan gindara atau escolar <em>(Lepidocybium flavobrunneum</em><em>)</em>, umumnya tertangkap sebagai hasil tangkapan sampingan <em>(bycatch)</em> pada perikanan rawai tuna Indonesia.  Penelitian dilakukan dengan metode observasi onboard pada armada rawai tuna yang berbasis di Pelabuhan Benoa mulai bulan Agustus 2005 - Desember 2009 yang beroperasi di Samudera Hindia. Tujuan penelitian ini adalah memberikan informasi daerah penangkapan, menganalisis parameter populasi (umur, pertumbuhan, mortalitas) dan laju eksploitasi ikan gindara hasil tangkapan kapal rawai tuna di Samudera Hindia. Hasil penelitian menunjukan  ikan gindara yang tertangkap oleh kapal rawai tuna menyebar pada posisi geografis antara  9<sup>0</sup>-33<sup>0</sup> LS dan 76<sup>0</sup>-127<sup>0</sup> BT dengan nilai laju pancing (HR) ikan gindara tertinggi  pada tahun 2007 sebesar 0,15 dan terendah tahun 2005 yaitu 0,04, atau  rata-rata HR sebesar 0,10.  Ikan  yang tertangkap memiliki ukuran panjang cagak antara 35-193 cm dengan rata-rata 87,4 cm. Parameter populasi yang dianalisa dengan program FiSAT II diperoleh panjang asimtotik (L∞) = 201,60 cmFL, koefisien laju pertumbuhan (K) = 0,21 per tahun dan t<sub>0</sub> = -0,4755 tahun. Nilai dugaan mortalitas total (Z) sebesar 0,85 per tahun, nilai dugaan mortalitas alami (M) = 0,37 per tahun dan laju mortalitas penangkapan (F) = 0,48 per tahun. Laju eksploitasi (E = 0,56) menunjukkan bahwa pemanfaatan gindara di Samudera Hindia diatas nilai optimum yang disarankan yaitu E = 0,50.</p><p><em>Escolar (Lepidocybium flavobrunneum) commonly caught as bycatch in Indonesia tuna longline fisheries. The study was conducted on August 2005 - December 2009 with onboard observation of tuna longliner  based in Benoa fishing  port. The objectives of this study are provide information about fishing ground, analyzing parameters of population (age, growth, mortality) and exploitation rate of escolar caught by Indonesia tuna longliner in the Indian Ocean. The results showed that escolar caught by tuna fleets longliner spread on latitude and longitude 90<sup>0</sup>-33<sup>0</sup> S and 76<sup>0</sup>-127<sup>0</sup> E with highest hook rate in 2007 at 0.15 and lowest hook rate occurred in 2005 at 0.04, with average HR at 0.10. Length frequency distribution of escolar were 35-193 cmFL with length average of 87.4 cm. The Von Bertalanffy growth parameter for escolar in Indian Ocean were L∞ = 201.60 cm, K = 0.21 year<sup>-1</sup> and t<sub>0</sub> = -0,4755 years. The annual instantaneous rate of total mortality (Z) was 0.85 year<sup>-1</sup>. T</em><em>he natural mortality (M) was</em><em> 0.37 year<sup>-1</sup> and the fishing mortality (F) was 0.48 year<sup>-1</sup>. </em><em>The exploitation rate (E = 0.56)</em><em> </em><em>indicating that escolar</em><em> in the Indian Ocean has reached the optimum limit.</em></p>

scholarly journals Stock depletion of yellowfin tuna Thunnus albacares (Bonnaterre 1788) in the Northeastern Indian Ocean

2021 ◽  
Vol 322 ◽  
pp. 05004
Author(s):  
Bram Setyadji ◽  
Hety Hartaty ◽  
Arief Wujdi ◽  
Ririk K. Sulistyaningsih
Keyword(s):  
Indian Ocean ◽  
Data Collection ◽  
Relative Abundance ◽  
Yellowfin Tuna ◽  
Coastal Communities ◽  
Thunnus Albacares ◽  
The Indian Ocean ◽  
Stock Depletion ◽  
Longline Fisheries ◽  
Tuna Longline

The stock of yellowfin tuna (Thunnus albacares) has been in a declining trend in the last five years. Although the noticeable decline mainly occurred in the western part of the Indian Ocean, uncertainty lingers on how this phenomenon will affect the opposite leg. The study aimed to investigate the dynamics of stock through monitoring several indicators by utilizing logbooks, scientific port sampling, and observer data available. The result showed that both relative abundance and estimated catch trend are declining in recent years, a sign that the negative global inclination also influences Indonesian tuna longline fisheries. Further studies are needed to understand whether this phenomenon also impacts other gears. Hence, mitigation on conserving the resource by reducing the catch and strengthening the data collection should be the priority to maintain the livelihood and welfare of many coastal communities.

scholarly journals Biology and fisheries aspects of Western Longnose Spurdog, Squalus edmundsi from the Eastern Indian Ocean, Indonesia

2017 ◽  
Vol 18 (4) ◽  
pp. 1714-1722
Author(s):  
FAHMI FAHMI ◽  
AGUS ARIFIN SENTOSA
Keyword(s):  
Indian Ocean ◽  
Seasonal Pattern ◽  
Eastern Indian Ocean ◽  
Size Distributions ◽  
Management Actions ◽  
Biological Aspects ◽  
The Government ◽  
Average Size ◽  
Longline Fisheries ◽  
Average Catch

Fahmi, Sentosa AR. 2017. Biology and fisheries aspects of Western Longnose Spurdog, Squalus edmundsi from the Eastern Indian Ocean, Indonesia. Biodiversitas 18: 1714-1722. A research has been done to determine some biological aspects of Western Longnose Spurdog (Squalus edmundsi) from the Eastern Indian Ocean Fishing Region in Indonesia (WPP 573). A total of 1797 samples were recorded from bottom longline fisheries at Tanjung Luar, Lombok from July 2015 to November 2016 by a trained enumerator. The study revealed that Selat Alas and the south west of Sumbawa waters are the most fished areas in the region for this species, with the peak fishing season may occur from January to March. The average catch rate of S. edmundsi was about 8 individuals per boat. The size of sharks varied from 470 mm to 1150 m total length (TL), with average size was 723.6±111.5 mm. Size distributions and sex ratio between females and males were significantly different, indicating a sexual dimorphism. This study revealed a fact that there was no seasonal pattern in the reproductive cycle of S. edmundsi in this region, which means the parturition may occur throughout the year. Analysis on its population status showed that this species was very susceptible to overfishing. This condition should be responded by the government through management actions for its fishery.

scholarly journals A Standardized Abundance Index from Fishery Independent Data: A Case Study of Swordfish (Xiphias Gladius) from Indonesian Tuna Longline Fishery

2020 ◽  
Vol 147 ◽  
pp. 02016
Author(s):  
Bram Setyadji ◽  
Zulkarnaen Fahmi
Keyword(s):  
Relative Abundance ◽  
Fishery Management ◽  
Negative Binomial ◽  
Stock Assessment ◽  
Information Criterion ◽  
Catch Per Unit Effort ◽  
Hurdle Models ◽  
Abundance Indices ◽  
Longline Fisheries ◽  
Tuna Longline

Most varieties of the billfish caught in the Indian Ocean are either swordfish or Indo-Pacific sailfish. Swordfish is mostly considered as by-catch from tuna longline fisheries, except for South African, Spanish and Portuguese fleets. Despite of its importance, little are known about their abundance. Relative abundance indices are the input data for stock assessment analyses that provide useful information for decision making and fishery management. In this paper, a Generalized Linear Model (GLM) was utilized to systematize the catch-per-unit-effort (CPUE) and to estimate relative abundance indices based on the Indonesian longline dataset. The data was collected by scientific observers from August 2005 to December 2016. Conventional models for counting data were used, but zero-inflated and hurdle models also considered, due to the high number of zero-catchper-set. Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) were applied to select the best models among all those evaluated. Both AIC and BIC suggested that the simple negative binomial (NB) model is the best option. The trends were relatively similar to the nominal series, but with smoother peaks. In general, there was a tendency of positive trends in the last decade, with the series varying throughout the period.

scholarly journals The shark by-catch of tuna longline fisheries in Southern Indian Ocean of Java, Indonesia

2018 ◽  
Vol 74 ◽  
pp. 02004
Author(s):  
Priyo Suharsono Sulaiman ◽  
Mufti Petala Patria ◽  
Rauf Achmad Sue
Keyword(s):  
Indian Ocean ◽  
Time Series Data ◽  
Southern Indian Ocean ◽  
Fishing Ground ◽  
Series Data ◽  
The Indian Ocean ◽  
By Catch ◽  
Catch Composition ◽  
Longline Fisheries ◽  
Tuna Longline

In relation to the achievement of the target SDG’s No. 14, the sustainable shark fisheries management need to implement. As a part of the tuna fisheries by-catch, a high number of shark resources have been caught in the Indian Ocean waters. One of the main vessels of tuna catchers in the Southern Indian Ocean of Java is the tuna longline from Cilacap. This paper aims to analyze the shark by-catch of tuna longline in the Indian Ocean in the south Java that landed in Cilacap. The research data was obtained from daily recording activities of fishing vessel loading activities by Cilacap Ocean Fisheries Port staff during the period of 2013-2017. The analysis was done through data tabulation, graphical approaches, and data trend analysis through the availability of time series data. The data analyzed include fleet development, fishing ground, catch composition and CPUE value. The results of the analysis show that there are about eight species of sharks that are by-catch of tuna longline from Cilacap. The highest shark by-catch occurred in April with CPUE averaging 9 kg/day/vessel. The blue shark (Prionace glauca) is the dominant shark catch which reaches 66% of the total sharks catch.

scholarly journals BIOLOGI REPRODUKSI, PERTUMBUHAN DAN MORTALITAS IKAN EKOR KUNING (Caesio cuning Bloch, 1791) DI PERAIRAN NATUNA

2018 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
Prihatiningsih Prihatiningsih ◽  
Isa Nagib Edrus ◽  
Bambang Sumiono
Keyword(s):  
Mortality Rate ◽  
Length Distribution ◽  
Total Mortality ◽  
Growth Parameter ◽  
Immature Stage ◽  
Optimum Level ◽  
Length Frequency ◽  
Potential Yield ◽  
Fish Samples ◽  
Exploitation Rate

Ikan ekor kuning (Caesio cuning) merupakan ikan ekonomis penting dan mendominasi hasil tangkapan bubu di perairan Natuna. Pada saat ini, produksinya merupakan dominan ke-2 setelah ikan bawal putih yaitu 2.891 ton/tahun (17,8% dari total produksi ikan). Populasi ikan ekor kuning sejak tahun 2008 menurun, diduga karena tingkat eksploitasi yang cenderung meningkat. Penelitian ini bertujuan mengkaji aspek biologi, meliputi reproduksi, pertumbuhan dan mortalitas ikan ekor kuning. Contoh ikan sebanyak 2.627 ekor dikumpulkan melalui tempat pendaratan ikan utama di Kijang, Pulau Bintan (Kepulauan Riau) dan Tanjung Pandan (Kepulauan Bangka Belitung) pada bulan Januari - Nopember 2014. Hasil penelitian menunjukkan sebaran ukuran panjang ikan ekor kuning berkisar antara 9,3-43,3 cmTL. Ikan yang tertangkap didominasi oleh belum matang gonad (immature). Musim pemijahannya berlangsung pada bulan Juni-Juli dan September-Oktober. Fekunditas telur yang matang gonad berkisar antara 13.355-151.632 butir. Panjang pertama kali ikan ekor kuning tertangkap dengan bubu adalah lebih kecil dari panjang pertama kali matang gonad (Lc<Lm), sehingga akan mengancam kelestariannya. Analisis pertumbuhan dengan uji-t diperoleh pertambahan panjang secepat pertambahan beratnya (isometrik). Aplikasi model analitik menggunakan program Electronic LEngth Frequency ANalisys-I (ELEFAN-I) diperoleh parameter pertumbuhan (=K) sebesar 0,6/tahun, panjang asimtotis (=L∞) sebesar 43,21 cmFL dan umur hipotesis ikan pada saat panjang sama dengan nol (=to) sebesar -0,24 tahun, sehingga persamaan pertumbuhan Von Bertalanffy sebagai Lt = 43,21 (1–e-0,6(t-0,24)). Parameter mortalitas menunjukkan laju kematian alami (=M) sebesar 1,17/tahun, laju kematian karena penangkapan (=F) sebesar 1,21/tahun dan laju kematian total (=Z) sebesar 2,38/tahun. Berdasarkan nilai F dan Z tersebut maka diperoleh estimasi laju eksploitasi (exploitation rate) sebesar 0,58 atau dalam kondisi sudah melampaui nilai optimum (E=0,5), sehingga pengelolaannya perlu segera dilakukan agar potensi lestarinya terjaga. The yellowtail fusilier (Caesio cuning) is one of the economically important fish caught by trap nets in Natuna waters. At present, the production of the yellowtail fusilier in Bintan regency as a second dominant fish species after white pomfret of 2.891 tons/year (17.8% of total landed). Population of the yellowtail fusiliers is likely decreasing since 2008 due to the increasing exploitation of this species. This study aims to assess the biological aspects including reproduction, growth and mortality of the yellowtail fusiliers. Monthly length frequencies data of 2.627 fish samples were collected through main landing place in Kijang, Bintan Island (Riau islands) and Tanjung Pandan (Bangka Belitung Islands) during January until November 2014. The results showed that the length distribution of the yellowtail fusilier ranged between 9.3 - 43.3 cmTL. The fish caught was dominated by the immature stage. The spawning seasons occurred between June-July and September-October. Fecundity of mature fish ranged between 13.355-151.632 eggs. The length of first capture by trap nets was under the length of first mature (Lc<Lm), so that will threaten its sustainability. Based on t-test it is showed that the weight growth pattern as fast as length growth (isometric). By using the analytical model application with Electronic LEngth Frequency ANalisys-I (ELEFAN-I) program, showed that the growth parameter (=K) was 0.6/yr, asymtotic length (=L∞) was 43.21 cmFl, and age at zero length (=to) was -0.24 yr, so the Von Bertalanffy’s equation growth curve were Lt = 43.21 (1–e-0,6(t-0,24)). Mortality parameters showed the natural mortality rate (=M) was 1.17/yr, fishing mortality rate (=F) was 1.21/yr, and total mortality rate (=Z) was 2.38/yr. Based on the values of F and Z obtained exploitation rate of 0.58 was likely exceed the optimum level (E=0.50) so that, management measures to maintain its potential yield should be applied. 

scholarly journals STANDARDIZING CPUE OF ALBACORE TUNA (Thunnus alalunga Bonnaterre, 1788) ON TUNA LONGLINE FISHERY IN EASTERN INDIAN OCEAN

2017 ◽  
Vol 23 (1) ◽  
pp. 29
Author(s):  
Fathur Rochman ◽  
Bram Setyadji ◽  
Arief Wujdi
Keyword(s):  
Indian Ocean ◽  
Relative Abundance ◽  
Eastern Indian Ocean ◽  
Series Data ◽  
Longline Fishery ◽  
Albacore Tuna ◽  
Fishing Vessels ◽  
Abundance Indices ◽  
Thunnus Alalunga ◽  
Tuna Longline

Albacore (Thunnus alalunga) is the third dominant catch of Indonesian tuna longline fishery operating in the eastern Indian Ocean. The percentage production of albacore catch was reaching up 6% of the total catch of tuna groups in Indonesia. Thi study aims to examine a relative abundance indices using standardized catch per unit of effort (CPUE) of longliner based on albacore tuna. This information will give a valuable input and information to support stock assessment particularly in the regional basis. In this study, we use Generalized Linear Model (GLM) with Tweedie distribution to standardize the CPUE and to estimate relative abundance indices based on the Indonesian longline dataset time series. Data were collected from January 2006 to October 2015 (106 trip observer and 8.989 fishing days) by conducting direct onboard observation on tuna longline vessels operating in the Indian Ocean. The result show that year, area,hooks between floats, year*season, year*area and year* hooks between floats significantly influenced the nominal CPUE of albacore. The highest value of Standardized CPUE appeared in 2014 and probably related to the large number of foreign fishing vessels with a high capacity (over 60 GT) targeting frozen tuna including albacore. In 2015, standardized CPUE value was sharply decreased due to the ban of foreign vessels in Indonesia. 

scholarly journals THE EFFECT OF DEPTH OF HOOKS, SET AND SOAK TIME TO THE CATCH PER UNIT OF EFFORT OF TUNA IN THE EASTERN INDIAN OCEAN

2017 ◽  
Vol 22 (2) ◽  
pp. 61
Author(s):  
Bram Setyadji ◽  
Budi Nugraha ◽  
Lilis Sadiyah
Keyword(s):  
Indian Ocean ◽  
Significant Relationship ◽  
Eastern Indian Ocean ◽  
Thunnus Albacares ◽  
Target Species ◽  
Hook Depth ◽  
Analytical Approaches ◽  
The Relationship ◽  
Fishing Area ◽  
Tuna Longline

Yellowfin (Thunnus albacares) and bigeye (T. obesus) tuna have been intensively exploited by longline fleets since 1980’s, however, a large proportion of zero catch per set of target species still accurred. Zero catch data contributed significantly to the low catch per unit of effort (CPUE) compared to other countries at the same fishing area. Therefore, understanding the factors contributed to the CPUE of tuna is essential, in order to improve longline fishing efficiency. A total of 2.115 set-by-set data were obtained from Indonesian Scientific Observer Program. The onboard observations were carried out at commercial tuna longline operated in Eastern Indian Ocean from August 2005 to December 2014. Several analytical approaches were conducted in this paper. First, General Linear Model (GLM) was applied in order to model the relationship between CPUE with all the variables involved. Second, boxplot diagram, polynomial and linear regression were applied to fit the relationship between CPUE with set time, soak time and depth (represented by hook position) respectively. The result showed that, there was no significant relationship between set time and CPUE of bigeye and yellowfin tuna. Soak time was positively related with CPUE of yellowfin and affect adversely on bigeye. Depth also have significant relationship with CPUE of tuna, where catch of yellowfin decreased linearly with hook depth, whereas catch of bigeye was performed the opposite. Improvement in tuna longline fishery in eastern Indian Ocean can be achieved through implementation of the specific soak time and hook depth for each target species, i.e. yellowfin and bigeye tuna.

Sign in / Sign up

Export Citation Format

Share Document