Kebiasaan Makan Hiu Kejen (Carcharinus Falciformis): Studi Kasus Pendaratan Hiu Di Ppp Muncar Jawa Timur (Feeding Habit of Silky Shark (Carcharinus Falciformis): Case Study of Landing Shark in Muncar Coastal Fishing Port East Java)

Indonesia is the biggest country which produced shark in the world. Muncar Coastal Fishing Port, Banyuwangi, is a shark fishing center in East Java. Caught sharks were dominated by silky shark (Carcharinus falciformis). Primary data collected by in situ sampling and stomach content analysis. Stomach content was collected by sectio. It preserved by 10% formaline in coolbox. Silky shark had caught by shark long line and gillnet. Shark is the fish target of longline and by-catch of gillnet. Silky shark preys were grouper fish (Epinephelus sp.) as main prey and squid (Loligo sp.), beltfish (Trichiurus lepturus), sardine (Sardinella lemuru) as complementary preys. Based on stomach content analysis, silky shark was identified on 4.7 trophic level. Silky shark preys were grouper on trophic level 4.1, squid, beltfish on trophic level 4.4, sardine on trophic level 2.1. Silky shark as apex predator could be found in Bali Strait and Makassar Strait, which it classified as fertility water. The existence of silky sharks whicht prey fish in several trophic level layers made silky shark as one of the key species in Bali Strait and Makassar Strait. Catching sharks will have implications for trophic level is high or low

KEBIASAAN MAKAN HIU KEJEN (Carcharinus falciformis): STUDI KASUS PENDARATAN HIU DI PPP MUNCAR JAWA TIMUR (Feeding habit of Silky Shark (Carcharinus falciformis): Case Study of Landing Shark in Muncar Coastal Fishing Port East Java)

ABSTRACTIndonesia is the biggest country which produced shark in the world. Muncar Coastal Fishing Port, Banyuwangi, is a shark fishing center in East Java. Caught sharks were dominated by silky shark (Carcharinus falciformis). Primary data collected by in situ sampling and stomach content analysis. Stomach content was collected by sectio. It preserved by 10% formaline in coolbox. Silky shark had caught by shark long line and gillnet. Shark is the fish target of longline and by-catch of gillnet. Silky shark preys were grouper fish (Epinephelus sp.) as main prey and squid (Loligo sp.), beltfish (Trichiurus lepturus), sardine (Sardinella lemuru) as complementary preys. Based on stomach content analysis, silky shark was identified on 4.7 trophic level. Silky shark preys were grouper on trophic level 4.1, squid, beltfish on trophic level 4.4, sardine on trophic level 2.1. Silky shark as apex predator could be found in Bali Strait and Makassar Strait, which it classified as fertility water. The existence of silky sharks whicht prey fish in several trophic level layers made silky shark as one of the key species in Bali Strait and Makassar Strait. Catching sharks will have implications for trophic level is high or low.Keywords: feeding habit, silky shark, trophic level-------ABSTRAKIndonesia merupakan negara penghasil hiu terbesar di dunia. PPP Muncar, Banyuwangi merupakan salah satu pusat penangkapan hiu di Jawa Timur. Hiu yang tertangkap oleh nelayan didominasi oleh hiu kejen (Carcharinus falciformis). Data primer didapatkan dari pengambilan sampel dan analisis isi lambung. Isi lambung didapatkan dari proses pembedahan. Isi lambung diawetkan dalam formalin 10% dalam coolbox. Hiu kejen tertangkap menggunakan rawai dan gillnet. Hiu menjadi ikan target pada alat tangkap rawai dan by-catch pada gillnet. Mangsa hiu kejen adalah kerapu sebagai makanan utama dan lemuru, cumi-cumi, layur merupakan makanan pelengkap. Hiu kejen (C.falciformis) yang tertangkap di Selat Bali berada pada trofik level 4,7. Mangsa utama hiu kejen adalah kerapu (trofik level 4,1) dan mangsa pelengkap lemuru (trofik level 2,1), layur (trofik level 4,4) dan cumi-cumi. Hiu kejen sebagai salah satu apex predator dapat ditemukan di Selat Bali maupun Selat Makassar yang memiliki kesuburan tinggi. Keberadaan hiu kejen yang memangsa beberapa ikan di beberapa lapisan trofik level menjadikan hiu kejen sebagai salah satu spesies kunci di perairan Selat Bali dan Selat Makassar. Penangkapan hiu akan memberi implikasi terhadap trofik level yang tinggi maupun rendah.Kata kunci: kebiasaan makan, hiu kejen, trofik leve

Shark and ray monitoring on the marine critical habitat in Aceh Province

Aceh is the leading province in Indonesia, where the marine protection area for juvenile sharks and rays was first established, precisely in Aceh Jaya waters. Rigaih is the fishing port located closest to Aceh Jaya waters, where the angler fish closely with the marine protected area and even intersect with the juvenile’s habitat. This study aimed to examine shark and ray catches in Aceh Jaya before and after establishing the marine protection area. We conducted landing monitoring from 2017 to 2019 (before establishing a conservation area) and monitored in 2020 when the conservation area was established. We recorded that 73% of sharks and ray caught on set gill net. The composition of sharks and rays landed at PPI Rigaih consisted of Sphyrna lewini (75%, n=1783), Chiloscyllium punctatum (8%), Neotrygon caeruleopunctata (7%, n =175), and other species (10%). This study aimed to provide scientific recommendations to support shark conservation action in Aceh Jaya Waters. We found that Aceh Jaya waters are an important area for the life stages of several threatened species, including Scalloped Hammerhead Sharks (S.lewini) and Bottlenose Wedgefish (R.australiae) that are listed in Critically Endangered and listed in Appendix II CITES. Management to support the conservation action needs to be strengthened not only limited to Marine Protected Areas but also fisheries management to reduce the incidental catch of threatened sharks and ray species. Further studies need to be conducted to delineate the habitat range of threatened shark and ray species and identify fishing behaviours that pose a risk for incidental catches of sharks and rays

Opportunities and challenges in value chain analysis for sustainable management of sharks and rays

Studies on elasmobranch trade have often focused on a single commodity, shark fins. Such a narrow focus can result in an incomplete understanding of the socio-cultural importance of sharks, limiting discussion on the range and efficacy of potential management interventions. Assessments must be performed across the value chain from fisher to retail vendor to better conserve vulnerable elasmobranch species, offering a broader view of capture, use, and trade. Here, we collate insights from shark value chain assessments conducted in eight countries (Mexico, Peru, Guinea-Bissau, India, Bangladesh, Sri Lanka, Indonesia and Fiji) spanning five continents. Approaches and processes implemented in a shark value chain analysis (VCA) were reviewed to: (1) understand better approaches and tools and (2) collate shared experiences. Our results demonstrate that VCAs broaden the outlook of fishery and trade assessments when capturing a more comprehensive range of economic and socio-cultural aspects (e.g., livelihoods, cultural use of commodities) of trade in all shark commodities. Time invested in various components of assessments produced different outcomes, with considerable returns from stakeholder selection, survey design, and assessor/stakeholder relationship building. Contrastingly, results demonstrated that efforts in communication with stakeholder groups and policymakers could be further streamlined to focus on key results using a variety of communication formats. Outcomes from this study offer guidance to those embarking on shark VCAs, facilitating improving the assessment process and outcomes

ASPEK BIOLOGI DAN KELIMPAHAN HIU MAKO SIRIP PENDEK (Isurus oxyrinchus) DI SAMUDRA HINDIA BAGIAN TIMUR BERDASARKAN PROGRAM OBSERVER ILMIAH 2015-2019

Hiu mako sirip pendek (Isurus oxyrinchus) termasuk kedalam Famili Lamnidae dan banyak dieksploitasi sehingga telah dimasukkan ke dalam daftar merah IUCN serta Apendiks II CITES sejak 2019. Penangkapan dan perdagangannya perlu dipantau secara global untuk menghindari kepunahan. Penelitian ini bertujuan untuk mengkaji laju tangkap, kelimpahan, dan estimasi ukuran hiu mako yang tertangkap perikanan rawai tuna. Pengumpulan data dilakukan dengan menempatkan tenaga observer ilmiah diatas kapal penangkap ikan yang berbasis di empat pelabuhan utama rawai tuna pada rentang waktu tahun 2015 hingga 2019. Bobot tubuh ikan diestimasi dari ukuran panjang cagaknya berdasarkan persamaan hubungan panjang dan bobot dari penelitian-penelitian sebelumnya. Hasil penelitian mengungkap bahwa terjadi peningkatan upaya rawai tuna seiring dengan peningkatan cakupan sampling. Laju tangkap mencapai puncaknya pada tahun 2017 (0,2 ekor/1000 pancing), kemudian mengalami penurunan seiring dengan peningkatan upaya penangkapan. Secara spasial, hiu mako tersebar di wilayah perairan tropis dan subtropis, khususnya kurang dari 10o Lintang Selatan. Pertumbuhan hiu mako bersifat isometrik dengan ukuran panjang cagak berkisar antara 50-211 cm. Rata-rata ukuran hiu yang tertangkap cenderung semakin besar dari tahun ke tahun sehingga dimungkinkan memiliki implikasi pada upaya pengelolaan dan konservasinya jenis yang terancam punah ini.Shortfin mako shark (Isurus oxyrinchus) belongs to the Family Lamnidae and is widely exploited so it has been included in the IUCN red list as well as Appendix II CITES since 2019. Hence, its capture and trade need to be monitored globally to avoid extinction. This study aimed to investigate the catch rate, abundance, and size estimation of the shortfin mako shark caught by tuna longline. Data collection was conducted through the on-board scientific observer program on the fishing vessel at four main tuna longline ports during the period of 2015 to 2019. The whole-body weight was estimated by its length and weight relationship revealed from previous studies. The results showed that there was an increase in fishing efforts along with an increased sampling coverage. The catch rates peaked in 2017 (0.2 fish/1000 hooks), then, it decreased due to increased fishing efforts. Shortfin mako sharks were distributed spatially in both tropic and subtropic waters, mostly caught in area below than 10-degree South. An isometric growth was identified with the length size ranged between 50-211 cm. The average size of harvested fish tends to rise every year that may have implications to the establishment of management and conservation strategies for the endangered species

Genetic connectivity of the scalloped hammerhead shark Sphyrna lewini across Indonesia and the Western Indian Ocean.

Scalloped Hammerhead shark (Sphyrna lewini) is an endangered species which its populations have been declining globally including in Indonesia, the world's top shark fishing country. However, there is a lack of information on the recent population structure of this species to promote proper management and its conservation status. This study aimed to investigate the genetic diversity, population structure, and connectivity of the S. lewini population, in three major shark landing sites: Aceh (n = 41), Balikpapan (n = 30), and Lombok (n = 29). Meanwhile, additional sequences were retrieved from West Papua (n = 14) and the Western Indian Ocean (n = 65) populations. From the analyses of the mitochondrial CO1 gene, a total of 179 sequences of S. lewini, with an average size of 594 bp, and 40 polymorphic loci in four and eight haplotypes for the Indonesian population and the Western Indian Ocean population were identified. The overall values of genetic diversity were high (h = 0.717; π = 0.013), with the highest values recorded in Aceh (h = 0.668; π = 0.002) and the lowest in Papua (h = 0.143; π = 0.000). On the contrary, the overall value was fairly low in the Western Indian Ocean (h = 0.232; π = 0.001). Furthermore, AMOVA and FST showed three significant subdivisions in Indonesia (FST = 0.442; P < 0.001), with separated populations for Aceh and West Papua, and mixed between Balikpapan and Lombok (FST = 0.044; P = 0.091). In contrast, genetic homogeneity was observed within the population of the Western Indian Ocean (FST = -0.013; P = 0.612). The establishment of a haplotype network provided evidence of a significantly different population and a limited genetic distribution between the Indonesian and the Western Indian Ocean populations (FST = 0.740; P < 0.001). This study showed the presence of a complex population of S. lewini with limited connectivity only in Indonesia separated from the Western Indian Ocean and requiring specific management measures based on the population structure at the regional level