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Bonito plays an important role as the main ingredient for marinated products and provides a livelihood for coastal communities. Given the emergence of Indonesia's over-exploited small-scale marine fisheries resources, this study aims to characterize and evaluate fishery’s sustainability based on bioeconomic analyses. Time series catch and effort data were collected from 2005 to 2019 provided by Archipelagic Fishing Port of Prigi. Five surplus production models were also employed to generate catch-and-effort-based biological parameters, namely intrinsic growth rate (r), catchability (q), and carrying capacity (K). By adding economy parameters such as cost and price, the sustainability of catch and effort was also estimated at three management conditions. The catch abundance was peaked in April and September, characterized by the lack of rain. The CPUE was varied inter-annually. However, it declined during the last decade, indicating that the stock size was decreased. Although the average catches from 2015-2019 (9,984 tons) are lower than CMSY (11,695 tons). However, the effort in 2019 (15,239 trips) has exceeded EMEY (14,237 trips). Hence, reducing fishing efforts or maintaining it at E2018 level was suggested as a precaution to keep the fishery’s sustainability and simultaneously generate optimum profit.

The stock status of yellowfin tuna (Thunnus albacares) (YFT) in the Indian Ocean is currently concluded overfished and is subject to overfishing. The information about the YFT population structure is fundamental for effective fisheries management and conservation. The otolith shape as a tool for estimating population structure is the cheapest technique compared to other methods, such as genetic, parasite, and otolith chemistry, especially for analyzing the large samples. This study investigates the use of otolith shapes to determine the yellowfin stock from two different locations. Data collection was carried out at two locations, namely Kedonganan and Benoa, throughout 2018. Total samples collected from the two study sites were 314 otoliths, but only 147 whole otoliths could be analyzed. Image analysis was performed using ANOVA-like permutation (n=1000 to determine whether the individual can be reclassified to their sample origin. The subsequent analysis is the variations in the shape of the otolith with multivariate statistical methods using cluster analysis with Canonical Analysis of Principal Coordinates. The result shows that the YFT otolith Benoa is significantly different from the YFT otolith Kedonganan with the P-value = 0.0015.

Penelitian tentang biologi reproduksi ikan dapat memberi data dan informasi penting mengenai frekuensi pemijahan, keberhasilan pemijahan, lama pemijahan serta ukuran ikan ketika pertama kali mencapai kematangan gonad. Penelitian ini bertujuan untuk mengetahui biologi reproduksi ikan lemadang (Coryphaena hippurus Linnaeus, 1758) yang tertangkap di perairan selatan Bali. Pengambilan sampel dilakukan pada bulan Mei-September 2018. Sebanyak 42 ekor ikan lemadang betina dengan kisaran panjang 41-10 cm FL diperoleh dari perikanan pancing ulur yang berbasis rumpon. Ovari dipreparasi dengan metode parafin dan pewarnaan Harris Hematoksilin-Eosin untuk pengamatan histologi gonad. Berdasarkan hasil penelitian, tingkat kematangan gonad pada ikan lemadang betina dewasa: spawning (38,10%), spawning capable (35,71%), regressing-potentially reproductive (4,76%), regressed 1 (2,38 %), regressed 2 (2,38%) dan regenerating (2,38%). Ikan yang belum dewasa: immature (9,52%) dan developing (4,76%). Diameter oosit berkisar antara 43,20 – 864,66 µm dengan rata-rata 430,99 µm. Fekunditas pada ikan lemadang betina dengan ukuran 49-75 cm FL berkisar antara 30.720-433.080 telur/ikan dengan rata-rata 129.594 telur/ikan. Perbedaan tingkat oosit dalam ovari pada saat yang sama menunjukkan bahwa ikan lemadang betina di perairan selatan Bali memiliki tipe perkembangan gonad yang asynchronous (tidak seragam) tipe fekunditas tidak menentu (indeterminant fecundity) dengan strategi pemijahan berganda (multiple spawning) dengan ukuran pertama kali matang gonad (Lm50) yaitu 43,2 cm FL. Kata kunci: ikan lemadang, histologi gonad, ukuran pertama kali matang gonad

Turtle is one of the vulnerable of megafauna and as a by-catch in tuna longline fisheries, however, management practices have not been done yet. This paper described the efforts to avoid the capture of turtles on the tuna longline fishery and its handling recommendation. It has been written based on the research results and observer programs of activities that have been implemented since 2005. It’s also including a literature review rules and regulations regarding the management of sea turtles. The record results during 2005 - 2014 conducted by an independent scientific board on tuna longline in the Indian Ocean with 72 times number of setting and 89,441number of hooks. There are 105 turtles caught, which are leatherback, olive ridley turtles, hawksbill, loggerhead sea turtles as well as the unknown green turtle where the current status of turtles in the Indian Ocean is in a state of vulnerable, endangered, critically even endangered. The olive ridley turtle, loggerhead and leatherback turtles are in a vulnerable status. While, the green turtles are in a state endangered and even hawksbill in a state extremely endangered. Policy measures for handling of turtles in tuna longline fishery needs to be taken in order to be implemented include the socialization of the use of intensified circle hooks and if necessary the government issued regulations regarding the use of circle hooks, the implementation of the placement of fishing monitoring (observer) aboard the tuna longline in order to assist the skippers monitoring the catch of turtles and turtle handling training for the skippers and crew in order to hold the caught turtles can be handled directly on the boat to reduce the mortality turtles which can be released back into the sea alive. Penyu merupakan salah satu biota yang rawan punah dan sebagai hasil tangkapan sampingan pada perikanan rawai tuna dimana pengelolaannya belum banyak dilakukan. Makalah ini membahas tentang upaya bagaimana menghindari tertangkapnya penyu dan rekomendasi penanganan penyu pada perikanan rawai tuna. Tulisan disusun berdasarkan penelusuran hasil penelitian maupun kegiatan program observer yang telah dilaksanakan sejak tahun 2005, dilengkapi kajian pustaka serta peraturan terkait pengelolaan penyu. Hasil pencatatan selama periode 2005 – 2014 yang dilakukan oleh pemantau ilmiah di kapal rawai tuna di Samudera Hindia dengan jumlah setting sebanyak 72 kali dan 89.441 buah pancing tertangkap 105 ekor penyu, yang terdiri dari penyu belimbing, penyu lekang, penyu sisik, penyu tempayan dan penyu hijau serta penyu yang tidak diketahui jenisnya dimana saat ini status penyu di Samudera Hindia berada dalam kondisi rentan, terancam punah bahkan sangat terancam punah. Penyu lekang, penyu tempayan dan penyu belimbing berada dalam status rentan. Sementara penyu hijau berada dalam keadaan terancam punah dan bahkan penyu sisik berada dalam keadaan sangat terancam punah. Langkah-langkah kebijakan penanganan penyu pada perikanan rawai tuna yang perlu dilaksanakan adalah mengintensifkan penggunaan pancing lingkar, perlu regulasi penggunaan pancing lingkar, implementasi penempatan pemantau penangkapan ikan (observer) di atas kapal rawai tuna agar dapat membantu para nahkoda memonitoring hasil tangkapan penyu dan pelatihan penanganan penyu bagi para nahkoda maupun anak buah kapal yang bertujuan agar penyu-penyu yang tertangkap dapat ditangani secara langsung di atas kapal sehingga menurunkan tingkat kematian penyu-penyu tersebut kemudian dapat dilepas kembali ke laut dalam kondisi hidup.

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

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).

Rawai tuna merupakan alat tangkap yang efektif untuk menangkap tuna dan ikan pelagis besar lainnya di perairan laut dalam. Pengoperasian rawai tuna bersifat pasif, sehingga tertangkapnya tuna ditentukan oleh tertariknya ikan untuk memakan umpan. Jenis umpan yang sering digunakan adalah lemuru, layang, bandeng dan cumi. Adanya perbedaan waktu setting pada rawai tuna mempengaruhi jenis umpan yang akan digunakan. Penelitian ini bertujuan untuk mengetahui pengaruh jenis umpan yang digunakan pada rawai tuna terhadap hasil tangkapan tuna, pada saat setting pagi dan sore hari. Metode penelitian dengan ujicoba penangkapan selama 2 trip menggunakan KM Putra Jaya 05 di Samudera Hindia. Trip 1 pada tanggal 18 Maret sampai 29 April 2007, sedangkan trip 2 pada tanggal 15 Juli sampai 23 September 2008. Hasil penelitian menunjukkan bahwa penggunaan jenis umpan layang, lemuru dan cumi pada setting sore hari berpengaruh nyata terhadap hasil tangkapan tuna, sedangkan penggunaan jenis umpan bandeng, lemuru dan cumi pada setting pagi hari tidak berpengaruh nyata terhadap hasil tangkapan tuna. Umpan cumi adalah jenis umpan terbaik yang digunakan untuk setting sore hari pada rawai tuna di Samudera Hindia. Tuna longline is an effective fishing gear to catch tuna and other large pelagic fish in the ocean. As a passive gear, the capture of tuna is depended on the attraction of fish to bait. The type of baits commonly used are sardine, milkfish, scad and squid. The different in setting time on tuna longline also influences the type of bait to be used. This research aims to determine the influence of bait used in the tuna longline on tuna catch, during setting in the morning and afternoon. Research methods to test the capture for 2 trips using the KM Putra Jaya 05 in Indian Ocean. First trip was on 18 March to 29 April 2007,and second trip was on 15 July to 23 September 2008. The results showed the use of bait type, i.e., scad, sardine and squid on the afternoon setting significantly affect the catch of tuna, while the use type of bait, i.e., milkfish, sardine and squid in the morning setting did not significantly affect the catch of tuna. Squid bait is the best type of bait used for the afternoon setting on tuna longline in the Indian Ocean.

Parameter biologi seperti umur dan pertumbuhan sangat penting untuk pengkajian stok sumber daya ikan dan pengelolaan perikanan agar pemanfaatan sumber daya ikan dapat dilakukan secara berkelanjutan. Informasi mengenai parameter pertumbuhan dari ikan madidihang di Samudera Hindia khususnya di Indonesia masih sangat terbatas. Penelitian ini ditujukan untuk memberikan informasi mengenai parameter pertumbuhan ikan madidihang. Pengumpulan data dilakukan selama tahun 2011, dengan cara pengukuran dan pengamatan langsung terhadap hasil tangkapan rawai tuna yang didaratkan di Pelabuhan Benoa, Bali. Total sampel yang diamati berjumlah 3.092 ekor. Kisaran panjang cagak (FL; fork length) ikan madidihang antara 75-179 cm dan kisaran bobot antara 8-101 kg. Dari hasil analisis data frekuensi panjang ikan madidihang diperoleh parameter pertumbuhan sebagai berikut: panjang asimtotik (L∞) 185,85 cm, koefisien pertumbuhan (K) 0,59 dan umur pada saat panjang 0 cm (t0) -0,22. Estimasi umur ikan madidihang yang didaratkan di Benoa tahun 2011 berkisar antara 1-5 tahun dengan laju pertumbuhan sebesar 2,95 cm/tahun. Pola pertumbuhan madidihang bersifat allometrik negatif. Pertumbuhan madidihang tidak akan mencapai ukuran panjang maksimum karena laju eksploitasi (E = 0,75) yang melebihi laju eksploitasi optimum (E opt = 0,5). Biological parameters suchas age and growth are very important information for accuracy of stock assessments and management to ensure that fisheries develop sustainably. Growth parameter information of Indian Ocean yellowfin tuna in Indonesia is still very limited. This research was aimed to determine the age and growth rate of yellowfin tuna that landed at Benoa port, Bali. Data of fork length (FL) and weight was collected during 2011. The data were measured and observed directly on the catch of tuna longline at Benoa Port, Bali. With numbers of fish samples was 3.092 fish. Age and growth rate was analyzed based on the FL using Von Bertalanffy model. The results showed that yellowfin tuna had range of FL between 75-179cm and weight range of 8-101kg. The growth parameter of yellowfin tuna has asymtotic length (L∞) 185,85 cm, K = 0,59 and t0 = -0,22. The age of yellowfin tuna landed in Benoa estimated between 1-5 years and growth rate was 2.95cm/year. Growth pattern of yellowfin tuna was allometric negative. The yellowfin growth will not reach the maximum length because the exploitation rate (E = 0,75) exceeds the optimum exploitation rate (E opt = 0,5).

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.

Knowledge of reproduction biology provides valuable information to better understanding population dynamics, including a population's resilience to fishing. The yellowfin tuna reproductive biology in the eastern Indian Ocean was studied by analyzing some essential characteristics: size at maturity, the spawning season, frequency of spawning, egg diameter, and batch fecundity. From 2018 to 2020, 206 female yellowfin tuna were sampled (23-170 cmFL). They were using histological and morphological analysis, resulting in the size at maturity (Lm50) of yellowfin tuna being 92.73 cmFL. The spawning season of yellowfin tuna occurred between September and May, spawning every 1.55 days within the spawning period. The oocytes size ranged between 27.1 – 570.5 μm, and the mean size of oocytes (mean ± standard deviation) was 189.5±129.4 μm. The mean batch fecundity was 3.1±1.7 million oocytes, and the mean relative batch was 82.4±38.4 oocytes gram-1 of GGT weight. The uncertainties in current yellowfin stock assessment models can be reduced by providing complete information on the reproductive traits in the region to achieve a sustainable fishery.

Tongkol komo (Euthynnus affinis) merupakan salah satu komoditas ekonomis tinggi perikanan tuna neritik, terutama bagi armada tuna skala kecil. Seiring dengan meningkatnya intensitas penangkapan pada satu dekade terakhir, diperlukan kajian kuantitatif terkait keberlangsungan stok. Akan tetapi, minimnya data yang tersedia pada perikanan jenis ini merupakan tantangan terbesar dalam melakukan usaha pengelolaan. Penelitian ini bertujuan untuk menduga parameter populasi dan rasio potensi pemijahan (SPR) berbasis ukuran panjang, sebagai titik acuan biologis kondisi stok dalam menghadapi tekanan penangkapan. Total 1.321 data ukuran panjang dikumpulkan secara acak setiap bulan selama Januari hingga Desember 2016 di Tanjung Luar. Parameter populasi meliputi pertumbuhan, kematian, rekrutmen, dan laju pemanfaatan diestimasi dengan metode ELEFAN. Analisis SPR juga dilakukan dengan melibatkan parameter reproduksi yang disintesis dari penelitian sebelumnya dengan paket LB-SPR. Hasil penelitian menunjukkan bahwa formula pertumbuhan von Bertalanffy diekspresikan dengan persamaan Lt = 85,0 (1-e-0,7 (t+0,173)). Meskipun rata-rata sampel tongkol komo diprediksi telah matang gonad/memijah (SL50>L50), namun sumberdaya tongkol komo mengalami tekanan yang tergolong tinggi dan mengganggu rekrutmen individu baru ke dalam stok yang diindikasikan dengan parameter lainnya seperti rasio mortalitas penangkapan relatif (F/M) = 2,15, laju eksploitasi (E) = 0,68, dan SPR = 23%. Oleh karena itu, diperlukan penyusunan pengelolaan yang efektif untuk kelestarian perikanan. Eastern little tuna or commercially known as kawakawa is listed as one of the most economically important species of neritic tuna, especially caught by small-scale tuna fisheries. Increasing fishing pressure in the last decade should be responded by a quantitative analysis on its stock. The problem arises when this typical fishery usually possesses limited time-series data. This study intended to estimate population parameters and spawning potential ratio (SPR) as a biological reference point to state the healthiness of fishery corresponding to the fishing pressure around coastal areas. A total of 1,321 length measurement data were randomly sampled monthly from January to December 2016 in Tanjung Luar. Population parameters including growth, mortality, recruitment, and exploitation rate were estimated by applying the ELEFAN method. SPR analysis was also carried out by involving reproduction parameters synthesized from previous studies using the LBSPR package. The results showed that the von Bertalanffy growth functions were expressed by the equation Lt = 85.0 (1-e-0.7(t + 0.173)). Although the majority of kawakawa was predicted in maturity as indicated by SL50>L50, high exploitation has occurred to the fishery that can be interfered the recruitment to the stock, as confirmed by other parameters, such as relative fishing mortality (F/M) = 2.15, exploitation rate (E) = 0.68, and SPR = 23%. Hence, the establishment of appropriate management strategies is needed to aim fishery sustainability.

Cakalang (Katsuwonus pelamis) adalah salah satu hasil tangkapan penting bagi nelayan di Samudera Hindia. Penelitian ini bertujuan untuk mengetahui perkembangan gonad dan panjang pertama kalimatang gonad cakalang di Samudera Hindia. Sampel cakalang dikumpulkan dari beberapa tempat di Pantai Selatan Jawa yaitu: Palabuhanratu, Cilacap, Pacitan, Sendang Biru, Kedonganan, Tanjung Luar, Labuhan Lombok dan Oeba dari bulan April 2012 sampai November 2013. Panjang cagak dari 136 sampel berkisar antara 35-68 cm. Tingkat kematangan gonad (TKG) diamati secara histologi dan analisis Gonadosomatic index (GSI). Hasil penelitian ini menunjukkan bahwa TKGcakalang didominasi oleh TKGIV sebesar 43%, diikuti dengan TKG III (21%), TKG I (17%), TKG II (16%) dan TKG V (2%). Panjang pertama kali matang gonad terjadi pada ukuran 42,9 cm. Skipjack tuna (Katsuwonus pelamis) is the one of the important catch for fishermen in the Indian Ocean. The objectives of this research are to investigate gonad maturity and length at first maturity for female cakalang in Indian Ocean. Skipjack tuna were sampled from several places in South Coast of Java i.e.: Palabuhanratu, Cilacap, Pacitan, Sendang Biru, Kedonganan, Tanjung Luar, Labuhan Lombok and Oeba from April 2012 to November 2013. Fork length of the sampled 136 fish ranged from 35 to 68 cm.Maturity stage (TKG) investigate using histological analysis and Gonadosomatic index (GSI) calculation. The results showed that maturity stage of skipjacktuna dominated by TKG IV with 43%, followed by TKG III (21%), TKG I (17%), TKG II (16%) dan TKG V (2%). Length at first maturity occurred at 42.9 cm.

Cakalang tergolong kelompok jenis ikan pelagis besar yang keberadaanya cukup melimpah di perairan Samudera Hindia termasuk perairan selatan Bali. Informasi biologi reproduksi sangat penting terutama untuk mengetahui kapan ikan tersebut memijah sehingga dapat digunakan sebagai dasar pengelolaannya. Cakalang memijah beberapa kali (multiple spawner), hal ini diketahui berdasarkan tingkat perkembangan oosit yang lebih dari satu tingkatan dalam satu gonad aktif. Sampel gonad cakalang betina diperoleh dari Pangkalan Pendaratan Ikan Kedonganan, Bali. Sebanyak 106 ekor cakalang betina dengan kisaran panjang cagak 37-71 cmFL dan kisaran bobot 902-7.214 gram yang teramati. Sampel gonad dalam keadaan segar langsung difiksasi menggunakan larutan buffer-formalin 10% kemudian dianalisis secara histologis menggunakan metode parafin dan pewarnaan HE (Harris-Haemotoxilin dan Eosin). Cakalang betina yang diklasifikasikan sebagai ikan yang belum dewasa (immature) memiliki karakteristik oosit unyolked (UY) yang lebih gelap pewarnaannya, memiliki diameter