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Genetic Diversity and Demography of Skipjack Tuna (Katsuwonus pelamis) In Southern and Western Part of Indonesian Waters Irwan Jatmiko; Raymon Rahmanov Zedta; Maya Agustina; Bram Setyadji
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 24, No 2 (2019): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Skipjack tuna (Katsuwonus pelamis) is highly migratory species that spread from trophic and sub trophic waters. This species can be found in Atlantic, Indian and Pacific oceans. The genetic information of highly migratory species like skipjack tuna is important to support the sustainability of the fisheries. The objectives of this study are to gain information genetic diversity and population structure of exploited species and to understand the population kinship in Indonesian waters. Tissue samples were collected from six locations, i.e.: Sibolga (North Sumatera), Padang (West Sumatera), Binuangeun (Banten), Pacitan (East Java), Lombok (West Nusa Tenggara) and Kupang (East Nusa Tenggara). Microsatellite analysis was done in this study consisting of extraction, purification, polymerase chain reaction (PCR) amplification and electrophoresis. Three loci used for the analysis i.e.: UTD 172, UTD 523 and UTD 535. The results showed that there are two groups from six locations i.e.: group 1: Sibolga and Padang; group 2: Binuangeun, Pacitan Lombok and Kupang. The variance among these two groups is 0.066 with variance 5.441%. This finding in line with Indonesian Fisheries Management Area of 572 (west of Sumatera waters) and 573 (south of Java waters). However, as highly migratory species across nations, the management strategy for skipjack tuna needs collaboration among countries through regional fisheries management authority like Indian Ocean Tuna Commission (IOTC).

The Effect of Moon Phase on The Catch of Bigeye Tuna (Thunnus obesus) in Eastern Indian Ocean Irwan Jatmiko; Bram Setyadji; Rani Ekawaty
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 21, No 3 (2016): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Tuna is one of the important export commodities to increase government income. One of economically important tuna species is bigeye tuna (Thunnus obesus) which has a proportion of 21% of the total production of large tuna group. The objective of this study was to investigate the effects of different moon phase on the catch of bigeye tuna (T. obesus) in Eastern Indian Ocean. Data collection was conducted by the scientific observers from August 2005 to June 2014 in the tuna longline vessels were based in the port of Benoa, Bali. Moon phase data were collected from August 2005 to June 2014 from National Aeronautics and Space Administration (NASA). Catch data were calculated using the catch rate formula which defined as the number of catches per 100 hooks. The number of catch rate then was sorted into each moon phases and were analyzed using one-way Anova. This study covered 62 trips and 1,480 numbers of operations or sets was conducted from sampled vessels. The result showed that the average catch rate of bigeye tuna differed significantly among the moon phases. Tukey post-hoc tests showed that the average catch rate at full moon was the highest among the groups with around 0.3/100 hooks. This study showed that moon phase had significant effect on the catch of bigeye tuna (T. obesus) that increased the catch during full moon. Keywords: moon phase, catch rate, Eastern Indian Ocea, tuna, Thunnus obesus

Distribution and Abundance of Fish Larvae in South of Alas Strait, West Nusa Tenggara Irwan Jatmiko; Fathur Rochman; Gussasta Levi Arnenda
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 23, No 2 (2018): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

The early life of fish larvae is important to understand the entire life history of the fish. At this phase, larvae movement is very weak and dependent on the movement of water currents. This study aims to determine the distribution and abundance of fish larvae in the waters south of the Port of Tanjung Luar, West Nusa Tenggara, Indonesia. Sampling of fish larvae were done at five stations at waters around Alas Strait and Indian Ocean south of East Lombok. Sampled were collected from 5 different depth: 0-200 m, 201-1000 m, 1001-2000 m, 2001-3000 m and >3000 m. A total of 122 fish larvae were collected which belong to 26 families and varied compositions among observation stations. The samples was dominated by Scombridae family (18 %), followed by Carrangidae and Blenniidae (13.1% and 6.6%, respectively). The highest abundance was occurred in station V (0-200 m) of 125 individuals.1000-1m3. It showed that inshore/shallow waters have more abundance than offshore/deep waters. The findings from this study can be basic information for the authorities to establish sustainable fisheries policy. Keywords: fish, larvae movement, sustainable fishery, early life.

CPUE STANDARDIZATION OF FRIGATE TUNA (Auxis thazard) CAUGHT BY PURSE SEINE IN THE WESTERN SUMATERA COAST (FMA 572) Ririk Kartika Sulistyaningsih; Irwan Jatmiko; Maya Agustina
Indonesian Fisheries Research Journal Vol 26, No 1 (2020): (June) 2020
Publisher : Research Center for Fisheries

Frigate tuna (Auxis thazard) is one of the major commercial tuna species, both in industrial and small scale fisheries, particularly in the waters off Western Sumatera. In Indonesia, A. thazard is a group of locally called “tongkol” together with A. rochei, Thunnus tonggol, and Euthynnus affinis. This study describes a preliminary examination of frigate tuna catch from purse seine off the coast of western Sumatera (FMA 572). The data were collected daily by an enumerator on the fish landing site from 2013 to 2017, including fishing gear, number of days at sea, catch, length, and weight of frigate tuna. The fishing ground coordinate data provided by the observer on board the vessel. General Linear Model (GLM) with gamma was applied in this study to standardize the CPUE by year, quarter, season, and GT as fixed variables. The results showed that the variation of CPUE was mostly influenced by year and quarter, while season and fleet size (GT) showed less impact on the catch. In general, even though the catch trend declines during the observation years, the population of frigate tuna off the coast of western Sumatera (FMA 572) were considered sustainable.

COMPARISON OF INDONESIAN TUNA LONGLINE FISHING PERFORMANCE WITHIN AND OUTSIDE INDONESIA EXCLUSIVE ECONOMIC ZONE (EEZ) Bram Setyadji; Irwan Jatmiko
Indonesian Fisheries Research Journal Vol 23, No 1 (2017): (June, 2017)
Publisher : Research Center for Fisheries

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).

CHARACTERISTIC OF SMALL SCALE TUNA FISHERIES ASSOCIATED WITH FADs IN LABUHAN LOMBOK, WEST NUSA TENGGARA-INDONESIA Fathur Rochman; Irwan Jatmiko; Zulkarnaen Fahmi
Indonesian Fisheries Research Journal Vol 25, No 1 (2019): (June) 2019
Publisher : Research Center for Fisheries

Fish aggregating devices, or FADs are used extensively in developing countries to attract and to collect pelagic fish and give positive impacts on fish production. Use of FADs has started in early 20th century with different names among the countries and regions. This study investigated the design, deployment, distribution, density and the number of FADs used by small scale tuna fisherman in Labuhan Lombok, including characteristics of fishing boat, fishing gear, catch composition, catch per unit of effort (CPUE), fish diversity and species richness. There were 65 FADs identified in this study and 47 of them were in normal distribution. Type of the FADs used was anchored FADs, spreading between 56.63 to 267.70 NM from Labuhan Lombok fishing port. The placement of FADs were arranged in such a way as to resemble a fence, in which the distance from one to another was close. It is expected to disrupt tuna movement towards the strait in the small islands around West Nusa Tenggara. The dimensional size of vessels used to catch fish was small boat (< 7 GT) with handline as fishing gears. Fish catches were dominated by skipjack (40.30%) followed by yellowfin tuna (30.90%), tuna juvenile (13.44%), frigate tuna (4.19%), albacore (3.41%), bigeye tuna (2.71%) and others (5.03%). The highest nominal CPUE occurred in January and February, accounted for 278 kg and 285 kg per day at sea respectively. The average diversity of fish and species richness in FADs area were 1.07674 and 1.3573 correspondingly. Overall results inform that diversity of fish, productivity and ecosystem were at sufficient condition and mid ecological pressure but species richness was in low condition. If this continues, it is possible that tuna diversity will decrease and endanger the survival of tuna species and others species related to the tuna.

DELTA MODEL APPROACH FOR CPUE STANDARDIZATION OF SWORDFISH (Xiphias gladius Linnaeus, 1978) CAUGHT BY INDONESIAN LONGLINE FLEET IN THE EASTERN INDIAN OCEAN Irwan Jatmiko; Humber Andrade; Budi Nugraha
Indonesian Fisheries Research Journal Vol 23, No 1 (2017): (June, 2017)
Publisher : Research Center for Fisheries

Relative abundance indices as calculated based on commercial catches are the input data to run stock assessment models to gather useful information for decision making in fishery management. A Generalized Linear Model (GLM) was used to calculate relative abundance indices and effect of longline fishing gear configuration. Data were collected by a scientific observer program from August 2005 to November 2013. Most of the boats monitored were based in the Benoa Port, Bali. Catches are often equal to zero because swordfish is a bycatch for Indonesian longline fleets. Therefore, a hurdle model and a binomial distribution was used to model the proportion of positive catch rates, while a gamma distribution were used to model the positive longline sets. Correlations between the proportion of positive sets and year () and quarter () were weak. However, linear correlation between the proportion of positive sets and the length of branch lines () and number of hooks between floats () were negative and significant. The probability of success is higher for surface longline with small number of hooks and short branch lines. Models with year in interactions as random effects did not converge. Models with year in interactions as fixed effects did converge, but the estimation of standard errors of year coefficients were high. Meaningful estimations were obtained only when using the simplest model, in which year is not in interactions. The low proportional decrease of deviance indicates that most of the variability of catch rates of swordfish caught by Indonesian longline boats are not related to year, quarter, number of hooks between floats and the length of branch lines. Other variables and information, like the daytime while the longlines deployed in the water (day or night), type of bait, size and type of hooks, and if the fishermen use light-sticks to attract the fish, are necessary to better understand the catch rate, and improve the estimations of the relative abundance indices.

ESTIMATION OF YELLOWFIN TUNA PRODUCTION LANDED IN BENOA PORT WITH WEIGHT-WEIGHT, LENGTH-WEIGHT RELATIONSHIPS AND CONDITION FACTOR APPROACHES Irwan Jatmiko; Hety Hartaty; Budi Nugraha
Indonesian Fisheries Research Journal Vol 22, No 2 (2016): (December, 2016)
Publisher : Research Center for Fisheries

Yellowfin tuna (Thunnus albacares) is one of the important catch for the fishing industry in Indonesia. Length-weight relationship study is one of important tools to support fisheries management. However it could not be done to yellowfin tuna landed in Benoa port since they are in the form of gilled-gutted condition. The objectives of this study are to determine the relationship between gilled-gutted weight (GW) and whole weight (WW), to calculate length weight relationship between fork length (FL) and estimated whole weight (WW) and to assess the relative condition factor (Kn) of yellowfin tuna in Eastern Indian Ocean. Data were collected from three landing sites i.e. Malang, East Java; Benoa, Bali and Kupang, East Nusa Tenggara from January 2013 to February 2014. Linear regression analysis applied to test the significance baseline between weight-weight relationships and log transformed length weight relationship. Relative condition factor (Kn) used to identify fish condition among length groups and months. The results showed a significant positive linear relationships between whole weight (WW) and gilled-gutted weight (GW) of T. albacares (p<0.001). There was a significant positive linier relationships between log transformed fork length and log transformed whole weight of T. albacares (p<0.001). Relative condition factor (Kn) showed declining pattern along with length increase and varied among months. The findings from this study provide data for management of yellowfin tuna stock and population.

DINAMIKA PERUBAHAN METODE PENANGKAPAN RAWAI TUNA DI SAMUDERA HINDIA Irwan Jatmiko; Fathur Rochman; Arief Wujdi
Jurnal Penelitian Perikanan Indonesia Vol 22, No 3 (2016): (September) 2016
Publisher : Pusat Riset Perikanan, BRSDM KP.

Rawai tuna merupakan salah satu alat tangkap penting bagi industri perikanan di Indonesia. Target utama alat tangkap ini adalah ikan tuna yang mempunyai nilai ekonomis penting seperti tuna mata besar dan madidihang. Penelitian ini bertujuan untuk mengetahui karakteristik kapal dan perubahan metode penangkapan rawai tuna di Indonesia. Pengumpulan data dilakukan oleh pemantau ilmiah (observer) pada kapal rawai tuna yang berbasis di Pelabuhan Benoa Bali, mulai Agustus 2005 hingga November 2014. Pemantau ilmiah mencatat data dan informasi meliputi: panjang tali cabang (PTC), panjang tali pelampung (PTP), panjang antar tali cabang (PATC), jumlah pancing antar pelampung (JPAP), jumlah mata pancing, lama waktu tebar pancing dan lama waktu perendaman. AnalisisAnova satu arah dan tes Tukey dilakukan untuk mengetahui perubahan karakteristik armada rawai tuna selama beberapa tahun. Hasil analisis menunjukkan terjadi perubahan karakteristik operasi rawai tuna selama beberapa tahun (p<0,05). Jarak antar tali cabang dan panjang tali pelampung berfluktuasi dengan menunjukkan pola yang acak. Jumlah mata pancing dan lama waktu tebar pancing juga berfluktuasi namun cenderung menurun jumlah dan durasinya. Selanjutnya, jumlah pancing antar pelampung juga memiliki kecendurungan lebih sedikit dalam kurun waktu beberapa tahun. Panjang tali cabang dan lama waktu perendaman menunjukkan peningkatan dalam panjang dan durasinya Hasil penelitian ini diharapkan dapat memberikan gambaran yang lebih lengkap terhadap perubahan karakteristik kapal rawai tuna Indonesia di Samudra Hindia. Tuna longline is one of the important fishing gears for the fisheries industry in Indonesia. The target species of this type of gear are a group of economically important tuna that have higher economic values such as bigeye tuna and yellowfin tuna. This study aims to investigate the fleet characteristics and the modification of fishing method of tuna longline in Indonesia. Data collection was conducted by scientific observers on tuna longline fishing vessels, mainly based in the port of Benoa Bali, from August 2005 to November 2014. The scientific observers record the information that will be tested were: length of branch line (LBL), length of float line (LFL), length between branch line (LBBL), number of hooks between floats (NHBF), number of hooks, length of set time and length of soak time. Analysis of one-way Anova and Tukey tests conducted to determine the changing characteristics of tuna longline fleets in several years. The analysis showed that changes in the characteristics of longline tuna operations for several years (p <0.05) were likely occurred. Length between branch line and length of float line were fluctuated with random pattern. Number of hooks and length of set time also fluctuated but tended to decrease in number and duration. Furthermore, number of hooks between floats also tends to decrease in recent years. Length of branch line and length of soak time showed an increase in the length and duration. The results of this study are expected to provide a more complete picture of the presence of changes in the characteristics of the Indonesian tuna longline fleets.

KARAKTERISTIK PERIKANAN PUKAT CINCIN PELAGIS BESAR DI PERAIRAN SAMUDRA HINDIA (WPPNRI 572 DAN 573) Irwan Jatmiko; Suciadi Catur Nugroho; Zulkarnaen Fahmi
Jurnal Penelitian Perikanan Indonesia Vol 26, No 1 (2020): (Maret) 2020
Publisher : Pusat Riset Perikanan, BRSDM KP.

Pukat cincin merupakan salah satu jenis alat penangkapan ikan yang digunakan oleh nelayan di Indonesia untuk menangkap ikan pelagis termasuk tuna dan cakalang. Cakalang dan madidihang/tuna sirip kuning merupakan komoditas perikanan penting di Indonesia untuk kebutuhan pasar domestik dan ekspor. Penelitian ini bertujuan untuk mengetahui karakteristik alat tangkap pukat cincin pelagis besar terutama yang menangkap cakalang dan madidihang di perairan WPPNRI 572 dan 573 (Samudra Hindia). Pengumpulan data dilakukan selama tiga tahun dari 2016-2018 di 18 pelabuhan perikanan yang armadanya melakukan aktivitas penangkapan di perairan WPPNRI 572 dan 573. Indikasi proporsi ikan yang sudah dan belum matang gonad dihitung dengan membandingkan ukuran ikan dengan ukuran pertama kali matang gonad (Lm). Hasil penelitian menunjukkan bahwa alat tangkap pukat cincin sangat dominan dalam mengeksploitasi sumber daya cakalang dan madidihang dengan proporsi mencapai 95% di WPPNRI 572 dan 66% di WPPNRI 573. Kebanyakan ikan yang tertangkap didominasi oleh ikan yang belum matang gonad dengan proporsi sebesar 67% untuk cakalang dan 94% untuk madidihang. Hasil analisis menunjukkan bahwa pukat cincin tidak termasuk alat yang selektif untuk menangkap ikan madidihang. Selanjutnya untuk target ikan cakalang, ukuran mata jaring harus diperbesar untuk mencegah tertangkapnya ikan yang belum matang gonad.Purse seine is one of dominant fishing gears used to catch pelagic species including skipjack and yellowfin tuna. They are two important commercial species in Indonesian as domestic and export commodities. This research aimed to analyze the characteristics of purse seine fishery focusing on skipjack and yellowfin tuna within FMA 572 and 573. All catch-effort data were collected from 18 fishing ports in three years, 2016-2018. All the vessels (purse seiners) were known to be actively fished within FMA 572 and 573. The proportion of mature and immature fish were calculated using the ratio of the fish length to its length at first maturity (Lm). The results showed that purse seine was a dominant gear to catch skipjack tuna and yellowfin tuna covering95% in FMA 572 and 66% in FMA 573, respectively. Most of the catches were dominated by immature fish with a proportion of 67% for skipjack tuna and 94% for yellowfin tuna. The analysis showed that purse seine is not an environmental-friendly gear to catchyellowfin tuna. Furthermore, for targeting skipjack tuna, the mesh-size of the net should be larger, allowing immature fish to escape from the gear.

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