scholarly journals Population Dynamics of Bullet Tuna (Auxis rochei Risso 1881) from the Indian Ocean, West Nusa Tenggara, Indonesia

2021 ◽  
Vol 13 (2) ◽  
pp. 144
Author(s):  
Evron Asrial ◽  
Ruly Isfatul Khasanah ◽  
Fathurriadi Fathrurriadi ◽  
Yasir Arapat ◽  
Usma Kurniawan Hadi ◽  
...  

Highlight Research:The bullet tuna (Auxis rochei) was identified and analysed.The length at first maturity (Lm) of bullet tuna (Auxis rochei) was analyzedThe eligibility status of bullet tuna (Auxis rochei) has been analyzed and estimatedThe LWR curve can be used to estimate age groups of fish compared to the sigmoid curveThe CF cannot be automatically used to estimate fish worth selling AbstractThe bullet tuna (Auxis rochei), BLT or tongkol lisong (Indonesian) is a species of neritic tuna which is one of the target fish for small scale fishers. The problem of bullet tuna fisheries was that it has reached overexploitation and the immature bullet tuna are still caught. This study aimed to assess the population dynamics of the BLT and its size composition caught by small scale fishers in the Indian Ocean, West Nusa Tenggara area was carried out in Bangko-Bangko (West Lombok), Cemplung Beach (South Sumbawa) and Tanjung Luar Fishing Port (East Lombok) between July 2019 and June 2020. The data was derived from the measurement and weighing results of 1,217 BLT collected from the respective collector traders at each sampling location. The growth pattern of BLT was isometric () which meant the ideal body shape (mesomorph) and length at first maturity (FLm) was 31.11 cm. The length-weight relationship curve showed that BLT was in an immature age group (adolescent fish). Meanwhile, the composition of BLT is worth selling (Condition Factor > 1.00), fit for catch (FLc / FLm > 1.00) and worthy of maturity (FLc > FLm), respectively 99.92%, 0.82% and 0.00%. The BLT fish composition indicates that the stocks of resources and populations do not support current sustainable fisheries management.

2017 ◽  
Vol 3 (2) ◽  
pp. 123
Author(s):  
Dian Novianto ◽  
Budi Nugraha ◽  
Andi Bahtiar

Ikan todak berparuh pendek atau ikan tumbuk atau shortbill spearfish (Tetrapturus angustirostris) merupakan salah satu hasil tangkapan sampingan rawai tuna. Informasi mengenai ikan todak berparuh pendek seperti komposisi ukuran, perbandingan kelamin, dan tingkat kematangan gonadsangat terbatas. Tulisan ini bertujuan untuk menyajikan data dan informasi mengenai aspek biologi ikan todak berparuh pendek yang merupakan hasil tangkapan sampingan dari rawai tuna yang beroperasi di Samudera Hindia. Penelitian ini dilakukan pada bulan September sampai Desember 2008 di perairan Samudera Hindia. Hasil penelitian menunjukan bahwa ikan todak berparuh pendek memiliki kisaran panjang tubuh 135-175 cmLJFL dan modus pada kisaran 155-165 cmLJFL.Perbandingan jenis kelamin ikan jantan dan betina 1:13,5, berdasarkan atas hasil uji chi-square menunjukan bahwa rasio ikan jantan dan betina pada periode penelitian ini tidak seimbang. Pada bulan September ikan todak berparuh pendek betina didominansi oleh tingkat kematangan gonad IIsebesar 66,7%, bulan Oktober oleh tingkat kematangan gonad V sebesar 46,2%, bulan Nopember oleh tingkat kematangan gonad II sebesar 53,3%, sedangkan pada bulan Desember oleh tingkat kematangan gonad III sebesar 42,9%. Pada bulan Nopember sampai Desember terlihat bahwa tingkat kematangan gonad V mulai berkurang, hal ini menunjukan bahwa pada bulan Nopember sampai Desember diduga banyak ikan todak berparuh pendek betina yang sudah memijah. Shortbill Spearfish (Tetrapturus angustirostris) is one of bycatch of tuna longline. Information about shortbill spearfish on the size composition, sex ratio, and maturity stage is still very limited. The objective this paper is to present the data and information about shortbill spearfish which is a bycatch of tuna longline that operated in the Indian Ocean. Research was conducted during September until December 2008 in Indian Ocean. The results showed that the shortbill spearfish have body length about 135-175 cmLJFL and modes in 155-165 cmLJFL. Sex ratio of the male and female was 1:13.5. Based on chi-square test showed that the ratio of male and female in the period of the study was not balanced. In September, the female stage maturity was dominated by level II of 66.7%, October by level V of 46.2%, November by level II of 53.3%, and December by level III of 42.9%. During November until December showed that the maturity stage of level V was decreased, this shows that in this time the female of shortbill spearfish was spawned.


2017 ◽  
Vol 23 (2) ◽  
pp. 77
Author(s):  
Arief Wujdi ◽  
Bram Setyadji ◽  
Suciadi Catur Nugroho

Ikan cakalang (Katsuwonus pelamis Linnaeus, 1758) yang tersebar luas di Samudra Hindia selatan Jawa, Bali dan Nusa Tenggara telah dieksploitasi secara terus menerus dengan berbagai alat tangkap. Pengelolaannya saat ini belum rasional karena masih diasumsikan sebagai unit stok tunggal tanpa adanya bukti ilmiah sehingga rentan mengalami lebih tangkap. Penelitian ini bertujuan untuk mengindentifikasi struktur stok ikan cakalang dengan teknik analisis bentuk otolith. Sampel otolith (saggittae) dikumpulkan pada bulan April, Agustus, dan September tahun 2016 di 4 lokasi, yaitu: Binuangeun, Sadeng, Prigi, dan Labuhan Lombok. Rekonstruksi bentuk otolith dilakukan dengan pendekatan outline analysis menggunakan teknik transformasi discrete wavelet. Uji statistik multivariate dengan kluster analisis menggunakan canonical analysis ofprincipal (CAP) dan uji ANOVA-like permutation juga diterapkan untuk menentukan signifikansi antar populasi. Hasil penelitian menunjukkan bahwa analisis bentuk otolith dapat digunakan sebagai penanda yang akurat untuk mengidentifikasi struktur stok. Bentuk otolith ikan cakalang bervariasi khususnya pada bagian rostrum, namun tidak berbeda nyata antar populasi (p>0,001). Hal tersebut berarti struktur stok ikan cakalang di Samudra Hindia (WPP NRI573) terdiri dari 1 populasi yang bergerak mengikuti pola perubahan lingkungan perairan di sepanjang Samudra Hindia. Skipjack tuna (Katsuwonus pelamis Linnaeus, 1758) distributed vastly along the Indian Ocean south of Java, Bali and Nusa Tenggara. It has been exploited by various fishing gear yet it always assumed to be a single stock. It was not based on scientific evidence but merely based on “a scientific assumption”, so that vulnerable to subject of overfishing. This research aims to examine the alternative tool for identifying the stock structure based on the otolith shape. Sampling location took place in four regions, namely: Binuangen, Sadeng, Prigi and Labuhan Lombok. The otolith (sagittae) samples was collected during April, August, and September 2016. The otolith shape was reconstructed using outline analysis with discrete wavelet transformation technique. A multivariate statistic using canonical analysis of principal (CAP) and ANOVA-like permutation test were also used to determine the signification among populations. The result showed that skipjack’s otolith shape was varied from one and another, especially in the rostrum. But it was not statistically different among regions (p>0.001), which means a single stock for skipjack in the Indian Ocean (Indonesian territory of FMA 573). This study also proved that otolith shape can be useful marker tool to identify stock structure for management purpose.


2021 ◽  
Vol 322 ◽  
pp. 03004
Author(s):  
Ignatius Tri Hargiyatno ◽  
Regi Fiji Anggawangsa ◽  
Moh. Natsir ◽  
I. Gede Bayu Sedana ◽  
Agustinus Anung Widodo ◽  
...  

There are two essential landing sites for handline tuna in Indonesia: Palabuhanratu (in the Indian Ocean) and Kendari (in the Banda Sea). This paper analyzes handline catches from the Indian Ocean and Banda Sea waters as the main fishing ground. The catch composition of the handline tuna landed in Kendari is more varied than Palabuhanratu. Several species commonly caught are yellowfin tuna (Thunnus albacares), skipjack tuna (Katsuwonus pelamis), bigeye tuna (Thunnus obesus) as a target species, and some billfish species as bycatch. Mean CPUE for handline tuna landed in Palabuhanratu is lower than Kendari. A significant difference is based on the monthly mean CPUE variation between Palabuhanratu and Kendari landing sites (p < 0.001). Handline catches in Palabuhanratu had a more comprehensive range of length sizes than Kendari, using a two-sample K-S test showed significant differences (p < 0.001). The fish size landed in Kendari is relatively smaller than Palabuhanratu. The average length of fish caught by handline is smaller than the length at first maturity (Lm) value in both landing sites. The use of large size hook for hand lines is recommended for catching tunas in this area.


2019 ◽  
Vol 25 (2) ◽  
pp. 135
Author(s):  
Hety Hartaty ◽  
Gussasta Levi Arnenda

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 <156 µm dan Early yolked (EY) yang memiliki diameter 114-249 µm. Cakalang dewasa (mature) memiliki karakteristik perkembangan ovari berupa adanya oosit pada tingkat yang lebih tinggi yaitu advanced yolked (AY) dengan diameter oosit berkisar antara 180-448 µm, migratory nucleus (MN) 239-468 µm dan hydrated (Hy) dimana ukuran oositnya sangat besar yaitu sekitar 459-552 µm dan berbentuk seperti noda merah muda (pink stain). Cakalang betina di perairan Samudera Hindia selatan Bali memiliki perkembangan oosit yang asynchronous (tidak seragam) yang ditandai oleh munculnya beberapa tingkat perkembangan oosit dalam satu ovari. Ukuran panjang pertama kali matang gonad (Lm) cakalang betina yaitu 44,7 cmFL. Cakalang betina dewasa yang berstatus memijah aktif (actively spawning) ditemukan di setiap bulan pengamatan (April-September) dan diduga memijah sepanjang tahun. Skipjack tuna is classified as a large pelagic fish species and has abundant presence in the waters of the Indian Ocean including the waters of southern Bali. Information related to reproductive biology is very important especially to find out when the fish spawn so that they can be used as a basis for its management. Skipjack spawns several times (multiple spawner), this is known based on the level of oocyte development that was more than one level in one active gonad. Samples of female skipjack gonads were obtained from Kedonganan, Bali. A total of 106 female skipjack tuna with length range of 37-71 cmFL and weight range of 902-7,214 grams were observed. Gonad samples in fresh condition were immediately fixed using a 10% buffer-formalin solution then histologically analyzed using the paraffin method and HE staining (Harris-Haemotoxilin and Eosin). Female skipjack classified as immature fish has the characteristics of unyolked oocytes (UY) which are darker in coloration, have a diameter <156 ìm and Early yolked (EY) which has a diameter of 114-249 ìm. Adult skipjack (mature) has the characteristics of ovarian development in the form of oocytes at a higher level, namely advanced yolked (AY) with oocyte diameter ranging from 180-448 µm, migratory nucleus (MN) 239-468 µm and hydrated (Hy) where oocyte size is very large, which is around 459-552 µm and shaped like a pink stain. Female skipjack in the waters of the Indian Ocean south of Bali has an asynchronous (non-uniform) oocyte development which is characterized by the appearance of several levels of oocyte development in one ovary. Size at first maturity (Lm) of female skipjack in Indian Ocean southern Bali was 44.7 cmFL. Adult skipjack females with active spawning status are found every month of observation (April-September) and suspected to spawn throughout the year.


2021 ◽  
Author(s):  
Helen E. Phillips ◽  
Amit Tandon ◽  
Ryo Furue ◽  
Raleigh Hood ◽  
Caroline Ummenhofer ◽  
...  

Abstract. Over the past decade, our understanding of the Indian Ocean has advanced through concerted efforts toward measuring the ocean circulation and its water properties, detecting changes in water masses, and linking physical processes to ecologically important variables. New circulation pathways and mechanisms have been discovered, which control atmospheric and oceanic mean state and variability. This review brings together new understanding of the ocean-atmosphere system in the Indian Ocean since the last comprehensive review, describing the Indian Ocean circulation patterns, air-sea interactions and climate variability. The second International Indian Ocean Expedition (IIOE-2) and related efforts have motivated the application of new technologies to deliver higher-resolution observations and models of Indian Ocean processes. As a result we are discovering the importance of small scale processes in setting the large-scale gradients and circulation, interactions between physical and biogeochemical processes, interactions between boundary currents and the interior, and between the surface and the deep ocean. In the last decade we have seen rapid warming of the Indian Ocean overlaid with extremes in the form of marine heatwaves. These events have motivated studies that have delivered new insight into the variability in ocean heat content and exchanges in the Indian Ocean, and climate variability on interannual to decadal timescales.This synthesis paper reviews the advances in these areas in the last decade.


Omni-Akuatika ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 92
Author(s):  
Heri Widiyastuti ◽  
Andina Ramadhani Putri Pane ◽  
Moh Fauzi ◽  
Thomas Hidayat

Mackerel scad (Decapterus macarellus) is one of the important economical caught in the Indian Ocean West Sumatra waters captured using purse seine. Increased production of mackerel scad will lead to increased exploitation, causing population changes. Therefore, research was carried out to find out the biological aspects of the fish so that resource management can be done. The sampling was conducted in Lampulo, Sibolga, and Air Bangis from February to November 2016 with total samples of 716 fishes. This research was conduct to study some biological aspects which consist of size distribution, length-weight relationship, sex ratio, gonad maturity level, the length at first capture, and length of the first maturity in Indian ocean west Sumatera waters. The results showed that the size of the mackerel scad had ranged between 16 - 33.6 cm FL and the average was 24.5 cm. Growth patterns are allometric negative, sex ratio male and female in an unbalanced condition. The mackerel scad is most caught by purse seine in maturity condition. The average length at first captured was 25.08 cm FL and length at first mature was 20.47 cm FL. These were an ideal biological condition and must be maintained because it provides an opportunity for fish to increase the population. The mesh size purse must follow the Ministry of Maritime Affairs and Fisheries Regulation Number 71/2016 that adjusted for minimum at 1 inch. Keywords: Mackerel scad, Indian Ocean, purse seine


2020 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Yoke Hany Restiangsih ◽  
Anthony Sisco Panggabean ◽  
Erfind Nurdin

Sumberdaya ikan cakalang (Katsuwonus pelamis) merupakan ikan ekonomis penting dan utama di Indonesia. Tingginya tingkat pemanfaatan ikan cakalang di Samudra Hindia menjadi hal yang sangat rawan dan perlu kehati-hatian dalam pengelolaannya. Tersedianya data dan informasi tentang musim pemijahan merupakan bagian dari pengetahuan yang diperlukan untuk mengetahui status sumberdaya bagi upaya pengelolaannya. Penelitian ikan cakalang dilakukan berdasarkan pengambilan contoh biologi dibeberapa tempat pendaratan ikan (Palabuhan Ratu, Prigi dan Labuhan Lombok). Penelitian dilaksanakan pada bulan Januari sampai dengan Nopember 2016. Pendugaan musim pemijahan menggunakan pendekatan indeks kematangan gonad (IKG) bulanan. Distribusi ukuran ikan yang tertangkap dengan menggunakan pancing tonda berkisar antara 24 – 66 cm. Ukuran rata-rata pertama kali tertangkap (Lc) pada panjang 41,6 cm, ukuran pertama kali matang gonad (Lm) 42,5 cm. Berdasarkan fluktuasi IKG musim pemijahan ikan diduga berlangsung pada bulan April dan Nopember.Skipjack tuna (Katsuwonus pelamis) are most important and economically fish in Indonesia. The highest exploitation skipjack in the Indian Ocean is very vulnerable are requires caution in its management. The availability of data and information about the spawning season is a part of the knowledge needed to determine the status of resources for management efforts. This research was carried out based on biological sampling at several fish landing sites (Palabuhanratu, Prigi, and Labuhan Lombok). This research was conducted from January until to November 2016. Estimating of the spawning season was used a monthly Gonado Somatic Index (GSI) approach. The range of size distribution from of fish caught using troll line were 24 until 66 cm. The average size of first caught (L50%) at a length was 41.6 cm, the size of the length of first maturity (Lm) was 42,5 cm. Based on the GSI fluctuation, spawning season was done in April and November.


2020 ◽  
Vol 26 (1) ◽  
pp. 11
Author(s):  
Agustinus Anung Widodo ◽  
Ignatius Trihargiyatno ◽  
Regi Fiji Anggawangsa ◽  
Wudianto Wudianto

Dalam rangka mendeskripsikan pemanfaatan dan inisiasi pengelolaan perikanan tuna neritik di WPPNRI 573, telah dilakukan penelitian dengan mengambil kasus perikanan tuna neritik berbasis di PPN Prigi-Jawa Timur. Data diperoleh melalui program port sampling pada tahun 2013-2017. Hasil penelitian menunjukkan produksi tuna neritik yaitu tongkol lisong (BLT), tongkol krai (FRI), tongkol komo (KAW), dan tongkol abu-abu (LOT) rata-rata sebesar 8.120 ton per tahun. Dari jumlah tersebut, 99,56% diproduksi melalui perikanan pukat cincin (PS) dan sisanya dari perikanan jaring insang hanyut (dGN), payang (DS), dan pancing tonda-pancing ulur (TR-sHL dan dHL). CPUE nominal PS selama 5 tahun terakhir terus menurun, rata-rata 0,891 ton/hari. Komposisi jenis tangkapan PS meliputi BLT (91,52 %), FRI (6,68 %), KAW (1,78 %) dan LOT (0,01 %). Sebanyak 99% BLT yang tertangkap PS merupakan ikan yuwana, sedangkan FRI, KAW, dan LOT sebagian besar tertangkap pada ukuran dewasa masing sebanyak 73%, 70%, dan 55%. Tuna neritik termasuk spesies peruaya jauh, maka pengelolaannya di WPPNRI 573 harus mengacu pada acuan pengelolaan Indian Ocean Tuna Commission (IOTC). Mengacu hasil Work Party Neritic Tuna (WPNT) IOTC tahun 2016 dan 2018, maka pengelolaan perikanan tuna neritik di WPPNRI 573 berbasis di PPN Prigi adalah sebagai berikut: (1) hingga 2025 jumlah hasil tangkapan BLT dan FRI harus dikendalikan masing-masing pada jumlah 9.818 ton dan 48 ton per tahun; (2) hingga 2023 tangkapan KAW ditetapkan pada jumlah ± 98 ton per tahun (80% jumlah tangkapan tahun 2013); dan (3) hingga tahun 2025 jumlah tangkapan LOT disarankan sama dengan tangkapan 2015 yaitu ± 1.13 ton per tahun. To describe the utilization and management initiation of tuna neritic fisheries in the Indonesian FMA-RI 573, a research has been conducted by taking the case at the Prigi Fishing Port, East Java. Data were obtained through the port sampling program in 2013-2017. Results show that the production of neritic tuna, namely bullet tuna (BLT), frigate tuna (FRI), kawa-kawa (KAW), and longtail tuna (LOT) was 8,120 tons per year on average. 99.56% of the amount were produced by purse seine (PS) fisheries, the rest came from drifting gill nets (dGN), danish-seine (DS), and the combination of trolling line and surface-deep hand line (TR-sHL and dHL) fisheries. The nominal CPUE of PS over the past 5 years has continued to decline, averaging 0.891 tons/day. The composition of PS catches includes BLT (91.52%), FRI (6.68%), KAW (1.78%) and LOT (0.01%). Large numbers (99%) of the BLT caught by PS were juvenile fish, while at the same time FRI, KAW, and LOT were mostly caught at the adult stage. Neritic tuna is a highly migratory species, so its management in the Indonesian FMARI 573 must refer to the Indian Ocean Tuna Commission-IOTC recommendations. Referring to the results of WPNT-IOTC in 2016 and 2018, the management of neritic tuna fisheries in the Indonesian FMA-RI 573 based at Prigi Fishing Port is as follows: (1) up to 2025, the catches of BLT and FRI must be controlled at 9,818 and 48 tons per year, respectively; (2) up to 2023, the catches of KAW are set at ± 98 tons per year (80% of the total catch in 2013); and (3) up to 2025, the catch of LOT is recommended the same as in 2015, which is ± 1.13 tons per year.


Author(s):  
Tom Hoogervorst

Southeast Asian history has seen remarkable levels of mobility and durable connections with the rest of the Indian Ocean. The archaeological record points to prehistoric circulations of material culture within the region. Through the power of monsoon sailing, these small-scale circuits coalesced into larger networks by the 5th century bce. Commercial relations with Chinese, Indian, and West Asian traders brought great prosperity to a number of Southeast Asian ports, which were described as places of immense wealth. Professional shipping, facilitated by local watercraft and crews, reveals the indigenous agency behind such long-distance maritime contacts. By the second half of the first millennium ce, ships from the Indo-Malayan world could be found as far west as coastal East Africa. Arabic and Persian merchants started to play a larger role in the Indian Ocean trade by the 8th century, importing spices and aromatic tree resins from sea-oriented polities such as Srivijaya and later Majapahit. From the 15th century, many coastal settlements in Southeast Asia embraced Islam, partly motivated by commercial interests. The arrival of Portuguese, Dutch, and British ships increased the scale of Indian Ocean commerce, including in the domains of capitalist production systems, conquest, slavery, indentured labor, and eventually free trade. During the colonial period, the Indian Ocean was incorporated into a truly global economy. While cultural and intellectual links between Southeast Asia and the wider Indian Ocean have persisted in the 21st century, commercial networks have declined in importance.


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