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Modelling the Diel Vertical Movement of Swordfish (Xiphias gladius Linnaeus, 1758) Based on Temperature and Depth Recorder Data Bram Setyadji; Hety Hartaty
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 21, No 1 (2016): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Understanding the vertical distribution of large pelagic fish, swordfish in particular, could improve our knowledge on its fisheries strategy, management and resource conservation. However the methods often require expensive tools and resources, which probably most scientists from the development countries couldn’t afford. Thus developing model on the diel vertical movement behavior of swordfish using number of hook between float (HBF) and complete-set temperature and depth recorder (TDR) data could be an alternative. In general context, capture depth distributions are a good indicator of the natural depth distribution of the fish if the entire depth range of the species is targeted by longline gear. The proposed sinusoidal model suggested that swordfish showed a diel pattern in depth distribution, marked by remained in the surface and mixed layer waters at night and dived into deeper waters during the day. Keywords: swordfish, behavior, HBF, TDR, sinusoidal model

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).

Fishing Season of Large Tuna from Purse Seine Fishery in Tumumpa, Manado, North Sulawesi Bram Setyadji; Umi Chodriyah
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 23, No 4 (2018): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Knowledge on seasonal fishing pattern is essential in fisheries research in order to increase the effectiveness of fishing and at the same time protecting the fishing ground from excessive fishing practices. Determining the seasonal fishing pattern of large pelagic fishes, namely large tuna (yellowfin and bigeye), small tuna (mackerel) and skipjack tuna were the objective of this study. Data from the 2013-2015 fishing operation time series were used to analyze the fishing season using the percentage average per unit effort (CPUE) method. The main focus of this study was purse seine fishery. The research showed that high fishing season of large pelagic fishes allegedly occurred during May to July, which reached its peak on May. On the other hand, low fishing season occurred during January to April, with the lowest on March. There were similarities between large tuna, small tuna and skipjack in term of their seasonal fishing pattern, although they did not show any good correlation (r<0.5). This might due to fact that even tough large tuna, small tuna and skipjack tuna shared the same ecological niche but apparently, they did not show any interaction (symbiosis) but competition.

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

THE EFFECT OF DEPTH OF HOOKS, SET AND SOAK TIME TO THE CATCH PER UNIT OF EFFORT OF TUNA IN THE EASTERN INDIAN OCEAN Bram Setyadji; Budi Nugraha; Lilis Sadiyah
Indonesian Fisheries Research Journal Vol 22, No 2 (2016): (December, 2016)
Publisher : Research Center for Fisheries

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.

THE SEASONAL VARIABILITY OF CPUE AND CATCH-AT-SIZE DISTRIBUTION OF TROLL AND HANDLINE TUNA FISHERIES LANDED IN LABUHAN LOMBOK Bram Setyadji; Hety Hartaty; Siti Mardlijah
Indonesian Fisheries Research Journal Vol 22, No 1 (2016): (June 2016)
Publisher : Research Center for Fisheries

Troll and hand line tuna fisheries is one of the major fishing gears landed in Labuhan Lombok coastal fishing port (PPP Labuhan Lombok) west Nusa Tenggara Barat province. Both fisheries are strongly associated with fish aggregating devices (FAD’s). The main fishing ground is Indian Ocean southern part of this province. Several source of data has been collected regularly. Data analysis comprised of monthlycatch and effort data samples based onport monitoring program during 2012 to 2015. The result showed the diclining of CPUE of yellow fin and skipjack tuna presumably related to fishing intensity of fleets and its variability that landed in PPP Labuhan Lombok. The increasing CPUE of skipjack tuna in 2014 was predicted due to increasing aggregation around the FADs. Constrasting seasonal fishing index pattern between yellowfin and skipjack tuna foundin 4-month cycles, started in January.A length-weight relationship suggested that yellowfin tuna caught bysmall-scale fisheries were performing allometric growth pattern (b=2.963, r2=0.9737).

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).

THE IMPACT OF ENVIRONMENTAL CHANGES ON BLACK MARLIN, Makaira indica (Cuvier, 1832) ABUNDANCES IN THE EASTERN INDIAN OCEAN Bram Setyadji; Zulkarnaen Fahmi
Indonesian Fisheries Research Journal Vol 26, No 1 (2020): (June) 2020
Publisher : Research Center for Fisheries

Black marlin (Makaira indica) is commonly caught as frozen by-catch from Indonesian tuna longline fleets. Its contribution estimated 18% (~2,500 tons) from total catch in Indian Ocean. Relative abundance indices as calculated based on commercial catches are the input data for several to run stock assessment analyses that provide models to gather information useful information for decision making and fishery management, however, little are known about the influence of environmental factors to its abundance. In this paper, the abundance was represented as standardized index in order to eliminate any bias on other factors which might influence it. Data were collected from August 2005 to December 2017 through scientific observer program (2005-2017) and national observer program (2016-2017). Most of the vessels monitored were based in Benoa Port, Bali. Overall, time trends of abundance was fluctuated, although, there was increasing trend since 2010 then dropped significantly into relatively similar figure in 2005. Even though, Sea Surface Temperature (SST) and Sea Surface Height (SSH) were statistically significant when incorporating into the models, but it allegedly wasn’t the main driver in determining the abundance of black marlin. Instead, it was more likely driven by spatio-temporal factors (year and area) effect rather than environmental changes.

PENGARUH FASE BULAN TERHADAP WAKTU TEBAR PANCING DAN LAJU TANGKAP MADIDIHANG (Thunnus albacares Bonnaterre, 1788) PADA ARMADA RAWAI TUNA Irwan Jatmiko; Bram Setyadji; Arief Wujdi
Jurnal Penelitian Perikanan Indonesia Vol 22, No 4 (2016): (Desember 2016)
Publisher : Pusat Riset Perikanan, BRSDM KP.

Madidihang/yellowfin tuna merupakan salah satu jenis ikan tuna ekonomis penting bagi industri perikanan di Indonesia dengan kontribusi hasil tangkapan yang terbanyak. Penelitian ini bertujuan untuk mengetahui pengaruh fase bulan terhadap waktu mulai tebar pancing dan laju tangkap madidihang pada armada rawai tuna. Pengumpulan data dilakukan oleh pemantau ilmiah pada armada rawai tuna yang sebagian besar berbasis di Pelabuhan Benoa, Bali mulai Agustus 2005 hingga Juni 2014. Daerah penangkapan ikan dari armada rawai tuna yang diambil datanya berada di lokasi (lintang dan bujur) 9°-16° LS hingga 109°-120° BT. Analisis anova satu arah dan tes Tukey dilakukan untuk mengetahui pengaruh fase bulan terhadap waktu mulai tebar pancing dan laju tangkap madidihang. Total sebanyak 60 trip dan 1.467 hari operasi penangkapan armada rawai tuna dilakukan dalam penelitian ini. Analisis statistik anova satu arah menunjukkan bahwa terdapat pengaruh yang nyata pada fase bulan terhadap waktu mulai tebar pancing (p<0,05). Selanjutnya, tes Tukey menunjukkan bahwa waktu mulai tebar pancing pada saat bulan purnama dimulai pada pukul 9:00 pagi hari. Waktu ini lebih lambat sekitar 2 jam dari pada waktu mulai tebar pancing pada ketiga fase bulan lainnya (perbani awal, perbani akhir dan bulan baru) yang dilakukan sekitar pukul 7:00 pagi hari. Analisis statistik anova satu arah juga menunjukkan terdapat perbedaan yang nyata antar fase bulan terhadap laju tangkap madidihang (p<0,05). Selanjutnya, tes Tukey menunjukkan bahwa laju tangkap pada saat bulan baru dan perbani awal sebesar 0,13 ekor/100 mata pancing atau lebih besar dibandingkan nilai laju tangkap pada saat purnama dan perbani akhir yang hanya sebesar 0,09 ekor/100 mata pancing. Yellowfin tuna is one of the most economically important species for fisheries industry in Indonesia. The objectives of this study are to investigate the effect of lunar phase to the set time start and catch rate of yellowfin tuna on tuna longline vessels. Data collected by scientific observer on tuna longline vessels mainly based in Benoa Port, Bali from August 2005 to June 2014. Fishing ground of sampled longline tuna located from 9°-16° S to 109°-120° E. One-way anova analysis and Tukey test conducted to examine the effect of lunar phase to the set time start and catch rate of yellowfin tuna. A total of 60 trips and 1,467 fishing days of longline tuna fishing vessels operation have been sampled for in this study. One-way anova analysis showed that there was a significant difference of lunar phase to the set time start (p<0.05). Furthermore, Tukey test showed that the starting time for setting during the full moon begins at 9:00 am. Its time was around 2 hours slower than the start of setting of the other three moon phase (first quarter, last quarter and new moon) which start around 7:00 am. One-way anova analysis also showed that there was a significant difference of lunar phase to catch rate of yellowfin tuna (p<0.05). Furthermore, Tukey test confirmed that hook rate on new moon and first quarter was 0.13/100 hooks or 0.4 bigger than hook rate on full moon and last quarter with only 0.09/100 hooks.

BEBERAPA PARAMETER POPULASI IKAN PEDANG (Xiphias gladius) DI SAMUDERA HINDIA BAGIAN TIMUR Bram Setyadji; I Wayan Arthana; I Wayan Kasa
BAWAL Widya Riset Perikanan Tangkap Vol 8, No 2 (2016): (Agustus 2016)
Publisher : Pusat Riset Perikanan, BRSDM KP.

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).

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