STUDY ON SPECIES COMPOSITION OF JUVENILE TUNA CAUGHT BY PURSE SEINE FLEET LANDING IN TAMPERAN FISHING PORT, JAVA, INDONESIA

Juvenile yellowfin tuna (Thunnus albacares) and bigeye tuna (T. obesus) are very similar in morphological characteristics, hence it is difficult to distinguish between these two species, especially when they are landed in frozen or defect conditions. The presence of juvenile bigeye tuna in yellowfin catch was first noticed in the 1980s from pole and line fisheries in Maldives. We analyzed the monthly composition structure of juvenile tuna caught by purse seine fleet operating in the South Indian Ocean. Tamperan fishing port was chosen for benchmarking to other small-scale fisheries. The result is expected to be used as an index for increasing the accuracy of juvenile tuna proportion for national catch statistics. A total of 4760 juvenile tunas were examined during monitoring activities. The length ranged 19-65 cm FL with median 40 cm FL for juvenile yellowfin tuna and 44 cm for juvenile bigeye. The whole weight of juvenile tuna ranged from 5 to 7 kg. The length-weight conversion for both species are W = 0.0184*FL3.0086 (R2 = 0.95, n = 4144) for juvenile yellowfin tuna and W = 0.018*FL3.0047 (R2 = 0.93, n = 346) for juvenile bigeye tuna. It can be inferred from the study that in terms of catch proportion of juvenile tuna, it consists of ratio 10:1, whereas for every 10 kg of juvenile tuna contains approximately one kg of bigeye tuna. Besides, the length-weight equation for both species is interchangeable, which means either equation can be performed to convert length to weight for both juvenile yellowfin and bigeye tuna

TINGKAT PEMANFAATAN SUMBER DAYA MADIDIHANG (Thunnus albacares) DI SAMUDRA HINDIA DENGAN PENDEKATAN ANALISIS SPAWNING POTENTIAL RATIO

Aktivitas penangkapan madidihang telah dilakukan secara terus menerus hingga saat ini karena memiliki nilai ekonomis yang tinggi. Sementara tingkat pemanfaatan sumber daya madidihang dalam beberapa tahun terakhir belum dipelajari dengan baik. Penelitian ini bertujuan untuk mengetahui tingkat pemanfaatan penangkapan madidihang di Indonesia dalam 10 tahun terakhir dan kondisi potensial daerah pemijahan. Analisis dilakukan dengan pendekatan Spawning Potential Ratio (SPR) berdasarkan data panjang cagak madidihang dari berbagai macam alat tangkap. SPR akan dijadikan sebagai titik rujukan biologi dalam memperkirakan tingkat pemanfaatan madidihang. Data panjang cagak yang dianalisis berjumlah 31.735 ekor, dengan panjang minimum 43 cmFL dan maksimum 183 cmF. Rerata panjang madidihang tersebut berkisar 103,7-143,8 cmFL dan terdistribusi secara normal. Madidihang yang tertangkap diasumsikan telah matang secara seksual atau matang gonad (SL50 > Lm). Status perikanan pada 2012, 2007, dan 2006 berdasarkan nilai SPR masuk ke dalam kategori over-exploited (SPR<20%), pada 2011 dan 2013-2018 masuk ke dalam kategori moderate (20% < SPR < 40%), sedangkan pada 2008, 2009, dan 2010 masuk ke dalam kategori under-exploited (SPR > 40%) yang bermakna bahwa pada tahun tersebut potensi pemanfaatan madidihang masih rendah dibandingkan nilai referensi biologi yang dimiliki madidihang.Yellowfin tuna fishing activity has been carried out continuously until now because it has a high economic value. Meanwhile, the level of yellowfin tuna resource utilization in recent years has not been well studied. This study aims to determine the utilization level of yellowfin tuna fishing in Indonesia and the potential conditions of spawning areas. The analysis was conducted using the Spawning Potential Ratio (SPR) approach based on the fork length data of yellowfin tuna from various fishing gears. SPR will be used as a biological reference point in estimating the exploitation rate of yellowfin tuna. The fork length data analyzed were 31,735 individuals, with a minimum length of 43 cmFL and maximum length of 183 cmFL. The mean length of yellowfin tuna ranged from 103.7-143.8 cmFL and normally distributed. Caught yellowfin tuna can be assumed to be sexually mature or gonadal maturity (SL50> Lm). Fishery status in 2012, 2007, and 2006 based on the SPR value was categorized as over-exploited (SPR <20%), in 2011 and 2013-2018 was categorized as moderate (20% <SPR <40%), while in 2008, 2009 and 2010 was categorized as under-exploited (SPR> 40%), which means that in those years, the potential utilization of yellowfin tuna is still low compared to the biological reference value of yellowfin tuna

OPTIMALISASI PCR IKAN TONGKOL KRAI (Auxis thazard) DAN LISONG (Auxis rochei) PADA ANALISIS KERAGAMAN GENETIK

Ikan tongkol lisong dan krai merupakan salah satu jenis tuna yang berperan nyata untuk usaha perikanan tangkap di Indonesia. Pengelolaan sumberdaya ikan tersebut harus selalu dapat dilakukan untuk menjaga tingkat pemanfaatannya supaya tidak lebih tangkap. Kajian keragaman genetik merupakan salah satu teknik dalam pengelolaan pemanfaatan sumberdaya perikanan dengan cara mengetahui tingkat keragaman genetik pada suatu struktur populasi. Kajian keragaman genetik ini diharapkan dapat menjadi basis kajian stok dan opsi dalam pengelolaan sumberdaya perikanan tongkol agar pemanfaatannya dapat dilakukan secara berkelanjutan. Awal mula analisis keragaman genetik dilakukan dengan memperbanyak DNA secara in vitro menggunakan teknik PCR (Polymerase Chain Reaction). Keberhasilan proses PCR dipengaruhi oleh beberapa faktor seperti suhu dan waktu penempelan oligonukleotida primer. Berdasarkan hal tersebut, penelitian ini bertujuan untuk mengetahui suhu dan waktu optimal pada primer Aro2-38. Sampel penelitian diperoleh dari hasil tangkapan pukat cincin yang didaratkan di PPN Palabuhanratu, Jawa Barat. Optimasi PCR menggunakan 12 suhu dan 2 waktu penempelan yang berbeda yaitu : 520C; 52,80C; 540C; 55,50C; 57,20C; 59,10C; 60,90C; 62,80C; 64,50C; 65,90C; 67,20C dan 680C, dan suhu penempelan 30 dan 15 detik. Hasil analisis menunjukkan bahwa produk PCR optimum (menghasilkan pita alel DNA) pada ikan tongkol krai berhasil waktu penempelan 30 detik dengan rentang suhu 52-540C. Sedangkan pada sampel ikan tongkol lisong, produk PCR yang optimum muncul pada waktu penempelan 15 dan 30 detik, dengan rentang suhu 52-60,90C.Frigate and bullet tuna constitute one of tuna species that plays a significant role in Indonesian fishing business. Management of fisheries resources must always be done to maintain the level of utilization so that it is not excessive. Genetic study is one of techniques in managing fisheries resource utilization by knowing the level of genetic diversity in a population structure. This genetic diversity study is expected to be the basis and option in the management of tuna fishing resources so that their utilization can be carried out sustainably. Genetic diversity analysis is start by multiplying fish DNA using PCR (Polymerase Chain Reaction) technique. The success of the PCR process is influenced by several factors such as temperature and time of primary oligonucleotide attachment. Based on this, this study aims to determine the optimal temperature and time in primers Aro2-38. The research sample was obtained from the catch of purse seine landed in PPN Palabuhanratu, West Java. PCR optimization uses 12 temperatures and 2 different annealing times: 520C; 52.80C; 54ÚC; 55,50C; 57.20C; 59.10C; 60.90C; 62.80C; 64,50C; 65,90C; 67.20C and 680C, and the annealing times are 30 and 15 seconds. The results of the analysis showed that the optimum PCR product (producing DNA allele bands) on the cretaceous tuna was successfully pasted for 30 seconds with a temperature range of 52-540C. Whereas in the sample of tuna lisong, the optimum PCR product appeared at the time of attachment of 15 and 30 seconds, with a temperature range of 52-60.90C

KERAGAMAN GENETIK TUNA MATA BESAR (Bigeye tuna, Thunnus obesus) DI SAMUDRA HINDIA BARAT SUMATERA DAN SELATAN JAWA

Salah satu cara yang digunakan untuk mendapatkan informasi tentang unit stok adalah dengan menggunakan pendekatan genetik. Informasi struktur populasi ini merupakan basis kajian stok dan opsi upaya pengelolaan agar pemanfaatannya dapat dilakukan secara lestari. Penelitian ini bertujuan untuk mendapatkan informasi variasi genetik dan struktur populasi tuna mata besar di Samudra Hindia. Sampel genetik yang berasal dari daging tuna mata besar dianalisis dengan metode chelex, PCR dan elektroforesis. Penelitian dilakukan pada bulan Januari sampai Desember 2015 dengan lokasi pengambilan sampel berada di perairan Samudra Hindia barat Sumatera dan Samudra Hindia selatan Jawa, Bali dan Nusa Tenggara. Hasil analisis menunjukkan bahwa keragaman genetik tuna mata besar di Samudra Hindia masih tinggi. Terdapat hubungan kekerabatan yang relatif dekat antar kelompok sampel populasi tuna mata besar di Samudra Hindia barat Sumatera dan selatan Jawa, Bali dan Nusa Tenggara. Variasi genetik diantara populasi tuna mata besar relatif kecil, namun variasi genetik dalam populasi relatif tinggi. Struktur populasi tuna mata besar di perairan Barat Sumatera dan Selatan Jawa-Nusa Tenggara (Samudra Hindia) masih merupakan satu stok populasi.One other technique that used to obtain information about stock units is to use a genetic approach. This genetic population structure information is the basis of stock assessmentand the options for how to manage the utilization can be done sustainably. This study aims to obtain information on genetic variation and population structure of large tuna populations in the Indian Ocean. Genetic samples derived from bigeye’s tuna flesh analyzed by using chelex, PCR and electrophoresis methods. This research carried out in the waters of the Indian Ocean west of Sumatra and the southern Indian Ocean of Java, Bali and Nusa Tenggara at January until December 2015. The results of the analysis show that the genetic diversity of large eye tuna in the Indian Ocean is still high. There is a relatively close relative relationship between bigeye tuna population groups in the Indian Ocean west of Sumatra and southern Java, Bali and Nusa Tenggara. Genetic variation among bigeye tuna populations is relatively small, but genetic variation in the population is relatively high. The population structure of bigeye tuna in West Sumatera and South Java-Nusa Tenggara (Indian Ocean) is still in one stock population

ESTIMASI PARAMETER POPULASI IKAN CAKALANG (Katsuwonus pelamis, Linnaeus, 1758) DI PERAIRAN SAMUDRA HINDIA

Penelitian ini bertujuan untuk mengkaji parameter populasi ikan cakalang (Katsuwonus pelamis) yang tertangkap pukat cincin di WPP-572 Samudra Hindia Barat Sumatera dan WPP-573 Selatan Jawa. Hasil penelitian ini diharapkan dapat digunakan sebagai masukan dalam penentuan pengelolaan perikanan sehingga stok ikan cakalang dapat dimanfaatkan secara berkelanjutan. Ikan contoh dikumpulkan melalui program enumerasi tahun 2016 (Januari-Desember). Sampling acak dilaksanakan di empat pelabuhan, yaitu PPS Lampulo (Aceh), PPN Sibolga (Sumatra Utara), PPP Tamperan (Pacitan) dan IPP Pondokdadap (Malang). Jumlah ikan contoh diperoleh sebanyak 14.894 ekor. Serial data fekuensi panjang bulanan diolah menggunakan program FiSAT II untuk menduga parameter pertumbuhan, mortalitas dan tingkat eksploitasi. Hasil penelitian menunjukkan ikan cakalang yang tertangkap di WPP-572 memiliki panjang asimtotik (L)73,5 cmFL, K sebesar 0.22/tahun dan to sebesar -0,59 tahun. Parameter populasi di WPP-573 berturut-turut L”=67,20 cmFL, K=0,27/tahun, dan to=-0,50 tahun. Nilai mortalitas alami (M) ikan cakalang di WPP 572 sebesar 0,49/tahun, mortalitas total (Z) 0,70/tahun, dan kematian akibat penangkapan (F) adalah 0,21/tahun. Ikan cakalang yang tertangkap di WPP 573 menunjukkan nilai (E) sebesar 0,59/tahun, nilai Z 1,02/tahun, dan nilai F sebesar 0,43/tahun. Dugaan tingkat eksploitasi ikan cakalang di WPP 572 dan 573 masing-masing 0,3/tahun dan 0,42/tahun atau belum berada pada tahap optimal.This study aimed to assess the population parameters of skipjack tuna (Katsuwonus pelamis) that caught by purse seine in the Indonesian FMA (Fisheries Management Area) 572 Indian Ocean West Sumatera and FMA 573 South Java. The outcomes of this research can hopefully be used as inputs for fisheries management, in order the stock of skipjack tuna can be utilized sustainably. Fish sample were collected through the program enumeration of Research Institute for Tuna Fisheries (RITF) during the year 2016 (Januari-Desember). Using random sampling method at four fishing ports, namely PPS Lampulo (Aceh), PPN Sibolga (North Sumatra), PPP Tamperan (Pacitan), and IPP Pondokdadap (Malang). The total number of fish samples was 14.894 fish. Monthly length frequency data processed using FiSAT II program to estimate the growth parameters, mortality, and exploitation. The analysis results showed that skipjack tuna caught in FMA 572 has asymtotic length value (L) at 73.5 cmFL, K value 0.22/year, and to at -0.59 year; while in FMA 573 population parameters values respectively 67.20 cmFL, 0.27/year, and -0.50 year. The value of natural mortality (M) skipjack in FMA 572 is 0.49/year, total mortality (Z) 0.70/year, and fishing mortality (F) 0.21/year. Skipjack tuna that caught in FMA 573 showed value of M 0.59/year, Z value 1.02/year, and F value 0.43/year. The estimated values of exploitation levels of skipjack in FMA 572 and 573 were 0.3/year and 0.42/year respectively

A Possible Mixing Genetic Pool of Eastern Little Tuna Euthynnus affinis Cantor (1849) from the Western and Southern Part of Indonesian Waters

Eastern little tuna (Euthynnus affinis) is a commercially important species for coastal communities in the western and southern part of Indonesia. However, little is known about its characteristics. Therefore, a comprehensive and broader research of its population structure is imminent in response to conserve and manage the fishery sustainably. This study aimed to fill the gap of the lacking information on the stock separation of eastern little tuna within the Indonesian archipelagic waters and its Economic Exclusive Zone (EEZ). Population genetic approaches were used to examine population structure using the mitochondrial DNA (mtDNA) control region marker. A total of 94 samples were collected from nine landing sites between January to September 2020. Polymerase chain reaction (PCR) was used to amplify the samples, and Sanger sequencing was used to sequence them. The findings showed a mean value of 0.922 for genetic diversity (Hd) and 0.009 for nucleotide diversity (π). Both of these numbers pointed to a high level of genetic diversity. A further population analyses using Analysis of Molecular Variance (AMOVA) and Discriminant Analysis of Principal Component (DAPC) confirmed a mixing gene pool with no distinct population structure detected (ΦST value of 0.097 and p-value>0.05)

Stock Health Bioindicator of Skipjack Tuna, Katsuwonus pelamis (Linnaeus, 1758) From Purse Seine Fishery in Western Part of Sumatra

The study focused on stock health bioindicator of skipjack tuna (i.e., size structure, length-weight relationship, and length-at-first-capture/Lc), which can be used as a reference for species-specific stock assessment in the western part of Sumatra waters. All size data were acquired from Kutaraja, Aceh, and Sibolga, North Sumatra, as part of the enumeration program, courtesy of the Research Institute for Tuna Fisheries, from January 2016 to December 2020. The result showed that the skipjack stock’s health is heading in an unsustainable direction. Further management actions are imminent to prevent any stock from declining shortly.Keywords: length-weight relationship, growth pattern, catch-at-size</jats:p

KEPADATAN OPTIMUM IKAN MAS KOKI KOMET (Carassius auratus auratus) PADA SISTEM PENGANGKUTAN TERTUTUP

This study aims to determine the optimum density of comet goldfish (Carassius auratus auratus) in the closed transportation system for 12 hours. Experimental method in this study used completely randomized design (CRD) which consists of 5 treatments (7, 12, 17, 22, and 27 fish/L) with 3 replications. The average weight of comet goldfish was 5 ± 0.5 g/fish obtained from Kediri, East Java. The results showed no mortality during the transportation. At the end of the adaptation of comet goldfish density of 7 fish/L had the highest survival rate is 96.82%, and a density of 27 fish/L had the lowest survival rate is 44.44%. Results showed that there were significant difference (P <0.05) between treatments in the adaptation period. The response relationship between the density and survival rate showed that higher density is lower the survival rate. The density of comet gold fish that produce highest survival rate was 7 fish/L, however based on technical or efficiency considertions in the transportation then the optimum density of of comet goldfish is 22 fish/L on the closed system transortatio

Genetic Diversity and Demography of Skipjack Tuna (Katsuwonus pelamis) In Southern and Western Part of Indonesian Waters

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).</jats:p

Age and Growth Estimation of Bigeye Tuna, Thunnus obesus (Lowe, 1839) in the Eastern Indian Ocean Deduced from Otolith Microstructure

Age-based stock assessment of globally important species, like bigeye tuna Thunnus obesus (Lowe, 1839), is urgently required to develop appropriate management plans for fisheries sustainability. This study aimed to estimate age and growth parameters using annual increments count of sectioned-otoliths, which effectively employed for age determination of tunas. Samples were collected from Indonesian tuna longline catch landed in the Port of Benoa from March until December 2017. Multi-models were employed to obtain robust growth parameters, and Akaike Information Criterion (AIC) was relied for the best fit model selection among those evaluated. Growth band formation was validated using marginal analysis (MI), indicating that one ring is deposited yearly and slow growth peaked during July (Australian winter). The von Bertalanffy growth model was selected as the best model fitting growth parameters from raw age data, as expressed as Lt = 183.49 (1-e-0.134(t+2.991)). Large variances in growth were detected at the same age, with the oldest age of 15. Over 50% of fish in the Indonesian catch were <5 years old, that may have implications for fisheries sustainability