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1
Nugroho, Duto, e Suherman Banon Atmaja. "KEBIJAKAN RUMPONISASI PERIKANAN PUKAT CINCIN INDONESIA YANG BEROPERASI DI PERAIRAN LAUT LEPAS". Jurnal Kebijakan Perikanan Indonesia 5, n. 2 (30 novembre 2013): 97. http://dx.doi.org/10.15578/jkpi.5.2.2013.97-106.
Testo completoAbstract (sommario):
<p>Penggunaan rumpon laut-dalam telah mengubah taktik dan strategi perikanan pukat cincin pelagis kecil yang beroperasi di perairan dangkal untuk bergeser pada perikanan tuna neritik tropis. Rumponisasi perikanan pukat cincin yang dirancang untuk meningkatkan produktivitas telah menjadi masalah serius pada perikanan neritik tuna. Hal ini terjadi karena tertangkapnya ikan berukuran kecil dalam jumlah yang dominan sehingga dalam jangka panjang akan berpotensi konflik dengan perikanan lainnya. Para ilmuwan yang tergabung dalam pengelolaan perikanan regional merekomendasikan bahwa pengembangan terkendali terhadap penggunaan rumpon di daerah asuhan juvenile tuna tropis. Pengendalian dalam jangka panjang dapat meminimalkan ancaman bagi kelangsungan hidup kelompok jenis tuna. Hal ini terkait dengan pentingnya memperbesar peluang masuknya sediaan kelompok jenis ini pada tingkat yang layak untuk dimanfaatkan. Di Indonesia, pilihan kebijakan perikanan tangkap baik melalui peralihan sasaran kelompok spesies maupun diversifikasi usaha penangkapan akan selalu bertumpu pada pertimbangan sosial. Bagaimanapun juga, proses mengubah pemahaman nelayan nelalui pengendalian jumlah dan teknologi kapal penangkap ikan serta penutupan sementara daerah penangkapan yang akan melalui proses panjang harus tetap dijalankan untuk mencegah runtuhnya perikanan yang saat ini sedang berjalan.</p><p>The use of Fish Aggregating Devices (FADs) has radically changing the tactic and strategy shallow waters small pelagic purse seiner into high seas tropical neritics tuna fisheries. Applying FADs on purse seine fishery which initiated to increase its productivity became a serious problem to neritics<br />tuna fishery. This indicated by the negative impact on neritics and tropical tuna populations due to large number of small size of tunas being caught and uncertain of number and of FADS position in the high seas. In the long run it will generate a potential conflict to other existing fisheries. The member scientists of regional fisheries management organization (RFMO) recommends that the development of the use of FADs, especially in the area which dominated of juvenile of tropical tuna, should be strongly regulated. FADs management through control system should be applied to minimize impact on recruitment process that associated with the importance of long term availability of its fisheries. Management option through shifting target species and diversification of the fishing activities in<br />Indonesia would always be rely on social dimension. Nevertheles, reorientation on fishers understanding on controllable number of fishing vessels and its technological creeps should strongly be implemented to avoid collapse their existing fisheries.</p>
2
Castro, C., K. Van Waerebeek, D. Cárdenas e JJ Alava. "Marine mammals used as bait for improvised fish aggregating devices in marine waters of Ecuador, eastern tropical Pacific". Endangered Species Research 41 (12 marzo 2020): 289–302. http://dx.doi.org/10.3354/esr01015.
Testo completoAbstract (sommario):
Fish aggregating devices (FADs) are floating objects typically used to attract and capture pelagic fish in industrial tuna fisheries. This study documents 9 cases, involving 31 marine mammals, of incidentally captured, killed or otherwise retrieved cetaceans and pinnipeds which were used, or presumably used, as bait for improvised fish aggregation devices (IFAD) by artisanal fishers in coastal Ecuador. At least 3 species of small cetaceans were affected, including pantropical spotted dolphin Stenella attenuata, short-finned pilot whale Globicephala macrorhynchus, pygmy killer whale Feresa attenuata and an unidentified small delphinid, as well as South American sea lions Otaria byronia which were reportedly killed on purpose for this fishing practice. A sperm whale Physeter macrocephalus and a humpback whale Megaptera novaeangliae were presumably found floating at sea and opportunistically exploited as FADs. The South American sea lion represented 80.6% of marine mammals used as bait associated with FADs (25 sea lions out of 31 marine mammals), while the remaining 5 (possibly 6) cetacean species represented 19.4%. This is the first report of baited FADs in Ecuador, the extent of which is still unknown. This fishing technique has not been documented in other nations along the west coast of South America, although baiting of gillnets with marine mammal parts is common in Peru. Without fisheries management and regulation, this illegal fishing practice could rapidly expand and lead to further direct kills and conservation problems for targeted marine mammal populations in the eastern tropical Pacific. A bottom-up fisheries policy in concert with community-based conservation to ban the use of marine mammals as FAD bait is recommended.
3
ALGHOZALI, FAQIH AKBAR, DIAH PERMATA WIJAYANTI e AGUS SABDONO. "Short Communication: Genetic diversity of scalloped hammerhead sharks (Sphyrna lewini) landed in Muncar Fishing Port, Banyuwangi". Biodiversitas Journal of Biological Diversity 20, n. 4 (29 marzo 2019): 1154–59. http://dx.doi.org/10.13057/biodiv/d200430.
Testo completoAbstract (sommario):
Abstract. Alghozali FA, Wijayanti DP, Sabdono A. 2019. Short Communication: Genetic diversity of scalloped hammerhead sharks (Sphyrna lewini) landed in Muncar Fishing Port, Banyuwangi. Biodiversitas 20: 1154-1159. The majority of sharks caught in Indonesian fisheries were bycatch products from the tuna longline fisheries, but some regions in Indonesia fish the sharks as their main target. One of these regions is located in Muncar, Banyuwangi, which fishes the endangered Scalloped Hammerhead sharks (Sphyrna lewini) as target species. This research aimed to study the genetic diversity of the endangered Scalloped Hammerhead sharks landed in Muncar Fishing Port, Banyuwangi. Genetic analysis was done through PCR (Polymerase Chain Reaction) amplification and sequencing of the mitochondrial DNA COI (Cytochrome Oxidase subunit I) gene. Out of the 37 samples collected, 30 were successfully amplified and sequenced.The results showed moderate haplotype diversity (Hd: 0,582 ± 0,079) and low nucleotide diversity (π: 0,00392± 0,0024) with five haplotypes (h) and 26 polymorphic sites (S). Tajima’s D neutrality model values indicated a population expansion event. Two different clades were determined through phylogenetic analysis and by GenBank sequences comparison. These results provided basic information and present status of the Scalloped Hammerhead sharks population genetically within the fishing ground (Makassar Strait-Kangean Islands).
4
Shafait, Faisal, Euan S. Harvey, Mark R. Shortis, Ajmal Mian, Mehdi Ravanbakhsh, James W. Seager, Philip F. Culverhouse, Danelle E. Cline e Duane R. Edgington. "Towards automating underwater measurement of fish length: a comparison of semi-automatic and manual stereo–video measurements". ICES Journal of Marine Science 74, n. 6 (27 febbraio 2017): 1690–701. http://dx.doi.org/10.1093/icesjms/fsx007.
Testo completoAbstract (sommario):
Abstract Underwater stereo–video systems are widely used for counting and measuring fish in aquaculture, fisheries, and conservation management. Length measurements are generated from stereo–video recordings by a software operator using a mouse to locate the head and tail of a fish in synchronized pairs of images. This data can be used to compare spatial and temporal changes in the mean length and biomass or frequency distributions of populations of fishes. Since the early 1990s stereo–video has also been used for measuring the lengths of fish in aquaculture for quota and farm management. However, the costs of the equipment, software, the time, and salary costs involved in post processing imagery manually and the subsequent delays in the availability of length information inhibit the adoption of this technology. We present a semi-automatic method for capturing stereo–video measurements to estimate the lengths of fish. We compare the time taken to make measurements of the same fish measured manually from stereo–video imagery to that measured semi-automatically. Using imagery recorded during transfers of Southern Bluefin Tuna (SBT) from tow cages to grow out cages, we demonstrate that the semi-automatic algorithm developed can obtain fork length measurements with an error of less than 1% of the true length and with at least a sixfold reduction in operator time in comparison to manual measurements. Of the 22 138 SBT recorded we were able to measure 52.6% (11 647) manually and 11.8% (2614) semi-automatically. For seven of the eight cage transfers recorde,d there were no statistical differences in the mean length, weight, or length frequency between manual and semi-automatic measurements. When the data were pooled across the eight cage transfers, there was no statistical difference in mean length or weight between the stereo–video-based manual and semi-automated measurements. Hence, the presented semi-automatic system can be deployed to significantly reduce the cost involved in adoption of stereo–video technology.
5
Griffiths, Shane P., Gary C. Fry, Fiona J. Manson e Richard D. Pillans. "Feeding dynamics, consumption rates and daily ration of longtail tuna (Thunnus tonggol) in Australian waters, with emphasis on the consumption of commercially important prawns". Marine and Freshwater Research 58, n. 4 (2007): 376. http://dx.doi.org/10.1071/mf06197.
Testo completoAbstract (sommario):
The feeding ecology of longtail tuna was studied in northern and eastern Australia. Diet biomass data were used to estimate daily ration and consumption of individual prey taxa, particularly penaeids targeted by Australia’s valuable Northern Prawn Fishery (NPF). Overall, the 497 stomachs contained 101 prey taxa. In both regions, small pelagic and demersal fishes comprised the majority of the diet biomass. Fish in both regions showed a marked increase in prey diversity, variation in prey composition and stomach fullness index in autumn and winter (March–August). This increase in apparently opportunistic feeding behaviour and feeding intensity showed an inverse relationship with reproductive activity, indicating a possible energy investment for gonad development. Daily ration decreased with increasing fish size, while annual consumption by fish increased with size. Total prey consumption in the Gulf of Carpentaria was estimated at 148178 t year–1. This includes 599 t year-1 of penaeids, equivalent to 11% of the annual NPF catch. This study demonstrated that longtail tuna play an important ecological role in neritic ecosystems. Their interaction with commercial fisheries highlights the need for targeted dietary studies of high order predators to better understand trophic pathways to facilitate ecosystem-based fisheries management.
6
Espenilla, Jacqueline Joyce F. "Sharing Fish: The Philippine Experience". Korean Journal of International and Comparative Law 8, n. 2 (15 dicembre 2020): 178–204. http://dx.doi.org/10.1163/22134484-12340136.
Testo completoAbstract (sommario):
Abstract Straddling and highly migratory fish such as tuna are the subject of immense interest from countries like the Philippines, whose populations are highly dependent on the oceans for both sustenance and livelihood. As these fish are transboundary by nature, they are deemed as “shared resources” that need to be cooperatively managed by country stakeholders in order to safeguard against depletion. This is the primary reason for the increasing number of international fisheries agreements as well as in the sudden prominence of regional fisheries management organizations (RFMO s). In that context, this article presents and analyzes the domestic drivers as well as the various international legal considerations that helped shape the current Philippine framework for the governance of shared fish, and reflects on how the twin goals of consumption/exploitation and conservation figure in the country’s fisheries policy.
7
Senina, Inna, Patrick Lehodey, John Sibert e John Hampton. "Integrating tagging and fisheries data into a spatial population dynamics model to improve its predictive skills". Canadian Journal of Fisheries and Aquatic Sciences 77, n. 3 (marzo 2020): 576–93. http://dx.doi.org/10.1139/cjfas-2018-0470.
Testo completoAbstract (sommario):
SEAPODYM is a model developed for investigating spatiotemporal dynamics of fish populations under the influence of both fishing and the environment. The model simulates age-structured population dynamics using advection–diffusion–reaction equations describing movement, recruitment, and natural and fishing mortality. The dynamic processes are constrained by environmental data and distributions of prey species. Model parameter estimation using fishing data was implemented earlier based on a maximum likelihood estimation (MLE) approach and adjoint technique. Here, we describe the integration of tagging data into the existing MLE approach with application to skipjack tuna (Katsuwonus pelamis) in the Pacific Ocean. We find that tagging data improve estimates of species habitat parameters and movement rates and hence allow better representation of spatial dynamics of fish population. Due to estimated lower diffusion and higher advection rates, the model predicts less non-observed “cryptic” biomass, which leads to the stock sizes being closer to those estimated by stock assessment models commonly used by tuna commissions.
8
Hearn, William S., Thomas Polacheck, Kenneth H. Pollock e Wade Whitelaw. "Estimation of tag reporting rates in agestructured multicomponent fisheries where one component has observers". Canadian Journal of Fisheries and Aquatic Sciences 56, n. 7 (1 luglio 1999): 1255–65. http://dx.doi.org/10.1139/f99-059.
Testo completoAbstract (sommario):
For many tagging experiments, it is vital that fishers find and report all tags to scientists. If not, the tag reporting rate needs to be estimated so that fishing and natural mortality rates can be estimated. One way to estimate this rate is to have one fishery component (e.g., with observers) report every tag found from all fish that it catches. If the numbers of fish caught by all fishery components are also known and the tagged fish are mixed with the population (or subpopulation) being harvested, then one can estimate the reporting rate of underreporting fishery components. This procedure can fail if data are pooled over ages. We obtain maximum likelihood estimators for the reporting rate for each age and (or) each fishery component. We show how to estimate reporting rates if mixing of tagged and untagged fish occurs with some delay. We also obtain overall age-dependent reporting rates, which combine reporting rates from all components of the fishery. Our likelihood is part of an integrated likelihood that allows estimation of age-dependent fishing and natural mortalities in addition to the reporting rates. Our procedures are illustrated with some southern bluefin tuna (Thunnus maccoyii) tagging data.
9
Widodo, Agustinus Anung, Fayakun Satria e Lilis Sadiyah. "STATUS PEMANFAATAN DAN PENGELOLAAN SUMBERDAYA IKAN TUNA NERITIK DI SAMUDERA HINDIA WPP 572 DAN 573". Jurnal Kebijakan Perikanan Indonesia 6, n. 1 (1 maggio 2014): 23. http://dx.doi.org/10.15578/jkpi.6.1.2014.23-28.
Testo completoAbstract (sommario):
<p>Dalam rangka mendeskripsikan status pemanfaatan dan pengelolaan sumberdaya tuna neritik di perairan Samudera Hindia (WPP 572 dan 573) telah dilakukan analisis terhadap informasi tentang jenis dan produksi tuna neritik yang disajikan dalam Statistik Perikanan Tangkap di Laut Menurut WPP tahun 2005-2012 (DJPT, 2013) serta data hasil penelitian berbasis di PPS Cilacap dan PPN Sibolga tahun 2011. Rekomendasi ‘working party’ tentang tuna neritik dari IOTC dikaji sebagai langkah pengelolaan perikanan tuna neritik di Indonesia. Hasil analisis dan kajian menunjukkan bahwa sumberdaya ikan tuna neritik yang tertangkap nelayan Indonesia di perairan WPP 572 dan 573 meliputi tongkol lisong (<em>Auxis rochei</em>), tongkol krai (<em>Auxis thazard</em>), tongkol komo atau kawakawa (<em>Euthynnus affinis</em>) dan tongkol abu-abu (<em>Thunnus tonggol</em>). Tuna neritik tertangkap sebagai by-product dari pukat cincin, jaring insang hanyut, pancing tonda, pancing ulur dan bagan. Tahun 2011 produksi neritik tuna di Samudera Hindia khususnya WPP 572 dan 573 mencapai 121.818 ton atau 29,4% dari total produksi tuna neritik nasional. Tuna neritik jenis tongkol lisong dan krai yang tertangkap jaring insang hanyut yang berbasis di Cilacap > 70% merupakan ikan yang telah dewasa. Adapun tongkol komo yang tertangkap pukat cincin yang berbasis di Sibolga sekitar 55,5% merupakan ikan dewasa. Belum ada langkah-langkah pengelolaan secara spesifik terhadap sumberdaya tuna neritik di Indonesia. Merujuk hasil Working Party on Neritic Tuna pertama dan kedua tahun 2011 dan 2012, Indian Ocean Tuna Commission (IOTC) merekomendasikan adanya kerjasama antar negara anggota IOTC yang saling berdekatan didalam melakukan pengelolaan sumberdaya neritik tuna. Langkah pertama adalah dilakukan perelitian mengenai populasi melalui studi mtDNA untuk memastikan status stok dan populasinya.</p><p> </p><p>The species of neritic tuna caught by fishers in the Indian Ocean particularly FMAs 572 and 573 consisted of frigate tuna (<em>Auxis thazard</em>), bullet tuna (<em>Auxis rochei</em>), longtail tuna (<em>Thunnus tonggol</em>) and kawa-kawa/eastern little tuna (<em>Euthynnus affinis</em>). These species are by-product of purse seine, drifting gillnet, trolling lines, and lift net. In 2011, production of the neritic tuna from FMAs 572 and 573 reached 121,818 mt or about 29.4% of the national production. More than 70% of catch of neritic tuna especially frigate and bullet tuna caught by drifting gillnet based at Cilacap were matured fish, and kawa-kawa caught by purse seine based at Sibolga about 55.5% of total catch was mature. There are no specific management measures for neritic tuna resources in Indonesia. First and Second IOTC Working Parties on Neritic Tuna in 2011 and 2012 recommended among IOTC’s member countries that are geographically close to each other to conduct a management collaboration of neritic tuna which begins with identifying the status of stock and population through a study mtDNA or other proper methodology.</p>
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Jatmiko, Irwan, Fathur Rochman e Maya Agustina. "VARIASI GENETIK MADIDIHANG (Thunnus albacares; Bonnaterre, 1788) DENGAN ANALISIS MIKROSATELIT DI PERAIRAN INDONESIA". Jurnal Penelitian Perikanan Indonesia 24, n. 3 (8 ottobre 2018): 157. http://dx.doi.org/10.15578/jppi.24.3.2018.157-164.
Testo completoAbstract (sommario):
Madidihang (Thunnus albacares) merupakan spesies yang bermigrasi jauh yang distribusinya di perairan tropis hingga perairan subtropis. Spesies ini ditemukan di Samudra Atlantik, Hindia dan Pasifik. Informasi genetik ikan dengan migrasi jauh seperti tuna penting diketahui untuk kepentingan pemanfaatan secara lestari. Penelitian ini bertujuan untuk memperoleh informasi keragaman genetik dan struktur populasi yang dieksploitasi dan kekerabatan populasi madidihang di perairan Indonesia. Pengumpulan sampel genetik dilakukan di tiga lokasi yaitu di Barat Sumatra, Selatan Bali dan perairan Sulawesi Utara. Metode yang digunakan adalah analisis mikrosatelit yang terdiri dari ekstraksi, purifikasi, amplifikasi polymerase chain reaction (PCR) dan elektroforesis. Hasil analisis terhadap 3 loci DNA mikrosatelit menunjukkan bahwa tingkat kekerabatan ketiga kelompok sampel relatif dekat yaitu berkisar antara 0,132-0,206. Hal ini menunjukkan bahwa Populasi madidihang di perairan Indonesia merupakan stok tunggal dan terjadi perkawinan acak. Meskipun demikian, sebagai spesies yang bermigrasi jauh lintas negara, pengelolaan madidihang juga memerlukan kerjasama yang baik antar negara yang tergabung dalam organisasi pengelolaan perikanan tuna regional.Yellowfin tuna (Thunnus albacares) is a highly migratory species that distribute from tropical to subtropical waters. This species can be found in the Atlantic, Indian and Pacific Oceans. Genetic information in fish with long distance migration such as tuna is very important for sustainable use. This study aims to obtain information on genetic diversity and population structure exploited and kinship of yellowfin tuna populations in Indonesian waters. Genetic sampling of yellowfin tuna was conducted in three locations in Indonesian waters in western Sumatra, southern Bali and North Sulawesi waters. The methods used was microsatellite analysis which consist of extraction, purification, polymerase chain reaction (PCR) amplification and electrophoresis. The result of 3 microsatellite DNA locus analysis showed that the level of kinship between the three sample groups in Indonesian waters was relatively close, ranging from 0.132 to 0.206. This shows that yellowfin tuna population in Indonesian waters is a single stock and random copulation. However, as a highly migratory species that migrate across the nations, yellowfin tuna management also requires good cooperation among countries incorporated in regional tuna fisheries management organizations.
11
Escalle, Lauriane, Daniel Gaertner, Pierre Chavance, Alicia Delgado de Molina, Javier Ariz e Bastien Mérigot. "Forecasted consequences of simulated FAD moratoria in the Atlantic and Indian Oceans on catches and bycatches". ICES Journal of Marine Science 74, n. 3 (13 dicembre 2016): 780–92. http://dx.doi.org/10.1093/icesjms/fsw187.
Testo completoAbstract (sommario):
Given the increasingly extensive use of drifting fish aggregation devices (FADs) by the purse-seine fisheries targeting tropical tunas, fishing effort restrictions have been introduced to manage tropical tuna stocks. However, these measures are focused on the protection of juvenile tunas and do not take account of the potential impact on bycatch or associated megafauna (whales and whale sharks). An iterative “fishing-day” Monte Carlo simulation model was developed to investigate the consequences on tropical tunas and bycatch of introducing extensive area 6-month moratoria on FAD activities. The model allowed for variability in a range of plausible values of the parameters characterizing the fishing operations conducted by European purse-seiners in the eastern tropical Atlantic and western Indian Oceans for the period 2005–2014. Monte Carlo simulations, using probabilities based on these fishery data, were carried out for the French and Spanish fishing fleets separately to account for differences in fishing strategies. The models predicted a decrease in FAD sets and an increase in free school sets. As a consequence, the catch of small tuna (<10 kg) decreased while the catch of large tuna (≥10 kg) increased, leading to an overall increase in tuna catch of 100–200 tons/year/vessel in the Atlantic Ocean, and a decrease of 400–1500 tons/year/vessel in the Indian Ocean. The bycatch decreased in the Indian Ocean, while in the Atlantic Ocean billfishes, turtles and chondrichthyans bycatch increased slightly and other bony fishes decreased. Because fishing practices were modified, whale and whale shark associated sets increased slightly in the Indian Ocean.
12
Juan-Jordá, M. J., I. Mosqueira, J. Freire e N. K. Dulvy. "Population declines of tuna and relatives depend on their speed of life". Proceedings of the Royal Society B: Biological Sciences 282, n. 1811 (22 luglio 2015): 20150322. http://dx.doi.org/10.1098/rspb.2015.0322.
Testo completoAbstract (sommario):
Larger-bodied species in a wide range of taxonomic groups including mammals, fishes and birds tend to decline more steeply and are at greater risk of extinction. Yet, the diversity in life histories is governed not only by body size, but also by time-related traits. A key question is whether this size-dependency of vulnerability also holds, not just locally, but globally across a wider range of environments. We test the relative importance of size- and time-related life-history traits and fishing mortality in determining population declines and current exploitation status in tunas and their relatives. We use high-quality datasets of half a century of population trajectories combined with population-level fishing mortalities and life-history traits. Time-related traits (e.g. growth rate), rather than size-related traits (e.g. maximum size), better explain the extent and rate of declines and current exploitation status across tuna assemblages, after controlling for fishing mortality. Consequently, there is strong geographical patterning in population declines, such that populations with slower life histories (found at higher cooler latitudes) have declined most and more steeply and have a higher probability of being overfished than populations with faster life histories (found at tropical latitudes). Hence, the strong, temperature-driven, latitudinal gradients in life-history traits may underlie the global patterning of population declines, fisheries collapses and local extinctions.
13
Morse, Molly R., Lisa A. Kerr, Benjamin Galuardi e Steven X. Cadrin. "Performance of stock assessments for mixed-population fisheries: the illustrative case of Atlantic bluefin tuna". ICES Journal of Marine Science 77, n. 6 (30 giugno 2020): 2043–55. http://dx.doi.org/10.1093/icesjms/fsaa082.
Testo completoAbstract (sommario):
Abstract Accounting for movement and mixing in stock assessment is important for managing sustainable fisheries, particularly for highly migratory species. However, many fisheries management approaches continue to use single-stock, single-area models to assess mixed-population stocks that are known to have complex movement dynamics. We evaluated a single-stock, single-area stock assessment model’s performance on fishery pseudodata generated using a spatially complex operating model that incorporates movement and mixing of simulated Atlantic bluefin tuna-like populations. Structural model misspecification produced positively biased perceptions of size and productivity of the smaller western population, based on supplement by the larger eastern population, and negatively biased perceptions of the size and productivity of the eastern population due to net movement of fish out of the eastern stock area. This bias could lead to unintended overexploitation of the smaller western population and potential for foregone yield of the larger eastern population. Our findings provide a greater understanding of the effects of movement and mixing on single-stock, single-area model-based management approaches and emphasize the importance of explicitly considering these dynamics in ensuring the sustainability of highly migratory species like Atlantic bluefin tuna.
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Campana, Steven E. "Transboundary movements, unmonitored fishing mortality, and ineffective international fisheries management pose risks for pelagic sharks in the Northwest Atlantic". Canadian Journal of Fisheries and Aquatic Sciences 73, n. 10 (ottobre 2016): 1599–607. http://dx.doi.org/10.1139/cjfas-2015-0502.
Testo completoAbstract (sommario):
The shortfin mako (Isurus oxyrinchus), porbeagle (Lamna nasus), and blue shark (Prionace glauca) are three frequently caught shark species in the northwestern Atlantic Ocean. Satellite tagging studies show that all three species range widely across many national boundaries but spend up to 92% of their time on the high seas, where they are largely unregulated and unmonitored. All are caught in large numbers by swordfish and tuna fishing fleets from a large number of nations, usually unintentionally, and all are unproductive by fish standards, which makes them particularly sensitive to fishing pressure. Landing statistics that grossly underrepresent actual catches, unreported discards that often exceed landings, and high discard mortality rates are threats to the populations and roadblocks to useful population monitoring. The influence of these threats is greatly magnified by inattention and ineffective management from the responsible management agency, the International Commission for the Conservation of Atlantic Tunas (ICCAT), whose prime focus is the more valuable swordfish and tuna stocks. Although practical management options are available, none will be possible if organizations like ICCAT continue to treat sharks like pests.
15
Lehodey, P., J. Alheit, M. Barange, T. Baumgartner, G. Beaugrand, K. Drinkwater, J. M. Fromentin et al. "Climate Variability, Fish, and Fisheries". Journal of Climate 19, n. 20 (15 ottobre 2006): 5009–30. http://dx.doi.org/10.1175/jcli3898.1.
Testo completoAbstract (sommario):
Abstract Fish population variability and fisheries activities are closely linked to weather and climate dynamics. While weather at sea directly affects fishing, environmental variability determines the distribution, migration, and abundance of fish. Fishery science grew up during the last century by integrating knowledge from oceanography, fish biology, marine ecology, and fish population dynamics, largely focused on the great Northern Hemisphere fisheries. During this period, understanding and explaining interannual fish recruitment variability became a major focus for fisheries oceanographers. Yet, the close link between climate and fisheries is best illustrated by the effect of “unexpected” events—that is, nonseasonal, and sometimes catastrophic—on fish exploitation, such as those associated with the El Niño–Southern Oscillation (ENSO). The observation that fish populations fluctuate at decadal time scales and show patterns of synchrony while being geographically separated drew attention to oceanographic processes driven by low-frequency signals, as reflected by indices tracking large-scale climate patterns such as the Pacific decadal oscillation (PDO) and the North Atlantic Oscillation (NAO). This low-frequency variability was first observed in catch fluctuations of small pelagic fish (anchovies and sardines), but similar effects soon emerged for larger fish such as salmon, various groundfish species, and some tuna species. Today, the availability of long time series of observations combined with major scientific advances in sampling and modeling the oceans’ ecosystems allows fisheries science to investigate processes generating variability in abundance, distribution, and dynamics of fish species at daily, decadal, and even centennial scales. These studies are central to the research program of Global Ocean Ecosystems Dynamics (GLOBEC). This review presents examples of relationships between climate variability and fisheries at these different time scales for species covering various marine ecosystems ranging from equatorial to subarctic regions. Some of the known mechanisms linking climate variability and exploited fish populations are described, as well as some leading hypotheses, and their implications for their management and for the modeling of their dynamics. It is concluded with recommendations for collaborative work between climatologists, oceanographers, and fisheries scientists to resolve some of the outstanding problems in the development of sustainable fisheries.
16
Bardey, Daniel Jonathan. "Overfishing: pressure on our oceans". Research in Agriculture Livestock and Fisheries 6, n. 3 (1 gennaio 2020): 397–404. http://dx.doi.org/10.3329/ralf.v6i3.44805.
Testo completoAbstract (sommario):
An increased demand for fish, combined with ever-growing global populations our oceans cannot keep up with the rate at which we are fishing our seas. As coastal fisheries declined, fishing started to expand into using open oceans as a resource leading to an 80% decline in bluefin tuna (Thunnus thynnus) and swordfish (Xiphias gladius) in just 5 years. Though overfishing for specific species can be beneficial, and even more surprisingly it’s encouraged. Off the coast of America, a new threat has been growing in recent years, the red lion fish (Pterois volitans). This species originally native to coral reefs in the South Pacific has recently found a new home the Atlantic Ocean. Target fishing the Lionfish will not only help reduce population size, minimize the chances of the Lion fish causing greater ecological damage on the Atlantic Ocean. Is moving public perception and demand towards invasive the next steps in protecting our fisheries?
Res. Agric., Livest. Fish.6(3): 397-404, December 2019
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Steadman, David W., e Sharyn Jones. "Long-Term Trends in Prehistoric Fishing and Hunting on Tobago, West Indies". Latin American Antiquity 17, n. 3 (settembre 2006): 316–34. http://dx.doi.org/10.2307/25063055.
Testo completoAbstract (sommario):
AbstractWe compare the bone assemblages of Milford 1 (TOB-3) and Golden Grove (TOB-13) in Tobago, West Indies. Milford 1 is a small preceramic occupation (ca. 3000-2800 cal B.P.), whereas Golden Grove is a large ceramic-period village (ca. 1700-900 cal B.P.). Species richness at TOB-13 is greater than at TOB-3, both in marine (67 vs. 39 fishes) and terrestrial (32 vs. 9) taxa. Major shifts in marine exploitation from the preceramic to ceramic periods can be seen in relative abundance of tuna, toadfishes, and in fishes inhabiting mangrove and brackish water environments, and decreases in relative abundance of parrotfish, carnivorous reef fishes, and sea turtles. The abundance of tuna bones at TOB-13 is uniquely high among West Indian archaeological sites. For terrestrial taxa, the difference in species richness exceeds the expected, including decreased specialization on big game (peccaries) at TOB-13, with a greater tendency to hunt reptiles, birds, and mammals of all sizes at TOB-3. Factors underlying the shifts in fishing and hunting may include different collection methods and food preferences of non-Arawakan (preceramic) vs. Arawakan (ceramic) peoples, as well as human-induced declines in populations of peccaries, sea turtles, and selected fish species. Another possible factor is site setting, with the inhabitants of TOB-13 having enhanced access to mangrove habitats.
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Shahul Hameed, Pentam Veli Pura, Aliyyathumada Ishyyapura Muhsin, Pathummathada Pookoya e Kutty Ranjeet. "Length–weight analysis of ten species (Actinopterygii) supporting subsistence fishery in Lakshadweep waters, southern Arabian Sea". Acta Ichthyologica et Piscatoria 51, n. 3 (9 settembre 2021): 257–61. http://dx.doi.org/10.3897/aiep.51.e64632.
Testo completoAbstract (sommario):
The length–weight relations of ten fish species representing eight genera and four families and that formed the backbone of the subsistence fishery in the Lakshadweep islands were estimated. These fishes which included four species of tuna [Katsuwonus pelamis (Linnaeus, 1758); Thunnus albacares (Bonnaterre, 1788); Auxis thazard (Lacepède, 1800); Euthynnus affinis (Cantor, 1849)], three species of needlefishes[Ablennes hians (Valenciennes, 1846); Tylosurus crocodilus (Péron et Leseur, 1821); Tylosurus acus melanotus (Bleeker, 1850)], two species of bait fishes [Spratelloides delicatulus (Bennett, 1832); Spratelloides gracilis (Temminck et Schlegel, 1846)], and one species of halfbeak (Hemiramphus archipelagicus Collette et Parin, 1978) contributed to 96% of the total fish landings. The samples were collected from fish landing centers of ten inhabited islands of Lakshadweep from 2015 to 2017. Katsuwonus pelamis showed isometric growth, S. delicatulus and S. gracilis exhibited positive allometry, while negative allometric growth was seen in other species. The coefficient a of the LWR ranged from 0.001 (A. hians) to 0.035 (T. albacares), while b ranged from 2.7 (T. acus melanotus) to 3.4 (S. delicatulus). The results of the presently reported study provide useful biological information on the stock of ten commercially important pelagic fish species supporting the traditional fisheries in Lakshadweep waters.
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Shahul Hameed, Pentam Veli Pura, Aliyyathumada Ishyyapura Muhsin, Pathummathada Pookoya e Kutty Ranjeet. "Length–weight analysis of ten species (Actinopterygii) supporting subsistence fishery in Lakshadweep waters, southern Arabian Sea". Acta Ichthyologica et Piscatoria 51, n. 3 (9 settembre 2021): 257–61. http://dx.doi.org/10.3897/aiep.51.64632.
Testo completoAbstract (sommario):
The length–weight relations of ten fish species representing eight genera and four families and that formed the backbone of the subsistence fishery in the Lakshadweep islands were estimated. These fishes which included four species of tuna [Katsuwonus pelamis (Linnaeus, 1758); Thunnus albacares (Bonnaterre, 1788); Auxis thazard (Lacepède, 1800); Euthynnus affinis (Cantor, 1849)], three species of needlefishes[Ablennes hians (Valenciennes, 1846); Tylosurus crocodilus (Péron et Leseur, 1821); Tylosurus acus melanotus (Bleeker, 1850)], two species of bait fishes [Spratelloides delicatulus (Bennett, 1832); Spratelloides gracilis (Temminck et Schlegel, 1846)], and one species of halfbeak (Hemiramphus archipelagicus Collette et Parin, 1978) contributed to 96% of the total fish landings. The samples were collected from fish landing centers of ten inhabited islands of Lakshadweep from 2015 to 2017. Katsuwonus pelamis showed isometric growth, S. delicatulus and S. gracilis exhibited positive allometry, while negative allometric growth was seen in other species. The coefficient a of the LWR ranged from 0.001 (A. hians) to 0.035 (T. albacares), while b ranged from 2.7 (T. acus melanotus) to 3.4 (S. delicatulus). The results of the presently reported study provide useful biological information on the stock of ten commercially important pelagic fish species supporting the traditional fisheries in Lakshadweep waters.
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Pertiwi, Lia Amelia, Hadi Susilo e Nurullah Asep Abdilah. "Microbiological and formaline test on the big eye tuna (Thunnus obesus Lowe, 1839) from fish auction place (TPI) and moving fish trader (PIK) in Panimbang Pandeglang Village Banten". Biological Environment and Pollution 1, n. 1 (30 giugno 2021): 38–45. http://dx.doi.org/10.31763/bioenvipo.v1i1.391.
Testo completoAbstract (sommario):
Big Eye Tuna (Thunnus obesus Lowe, 1839) is one of the fish species that can increase sources of animal protein and has high economic value in the world of trade because it is the second-largest export commodity after shrimp. The purpose of this study was to test the content of microbial and formalin contamination in the flesh of T. obesus fish from the Fish Auction Place (TPI) and Mobile Fish Trader (PIK) in Panimbang Village, Pandeglang, Banten. The research was carried out at the Regional Technical Implementation Unit (UPTD) Testing and Application of Quality of Fishery Products, Department of Marine Affairs, and Fisheries of Banten Province. This research is a descriptive laboratory study with purposive sampling. Twelve samples of T. obesus fish obtained from TPI (6 fishes) and PIK (6 fishes) were taken for 25 g of meat. The tested for microbial contamination content with Total Plate Count (TPC) using Butterfield's phosphate (BFP) media, and Plate Count Agar (PCA), Coliform-Test, and E. coli-Test using Lauryl Tryptose Broth (LTB). Brilliant Green Lactose Bile (BGLB), EC Broth and Levine's Eosin Methylene Blue (LEMB), and Formaldehyde-Test using Formaldehyde-Test Kits. The results showed that the flesh of T. obesus fish contained microbial contamination with the average values of TPC, Coliform MPN, and E. coli MPN, respectively, namely 1.6 103 colony/g, 15.2 MPN/g and < 3 MPN/g ( TPI), and 1,7103 colony/g, 61.3 MPN/g and < 3 MPN/g (PIK). Therefore, fish in TPI and PIK are safe for consumption as stipulated in SNI.
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Farley, Jessica H., Naomi P. Clear, Bruno Leroy, Tim L. O. Davis e Geoff McPherson. "Age, growth and preliminary estimates of maturity of bigeye tuna, Thunnus obesus, in the Australian region". Marine and Freshwater Research 57, n. 7 (2006): 713. http://dx.doi.org/10.1071/mf05255.
Testo completoAbstract (sommario):
Biological parameters such as age, growth and age (or size) at maturity are vital for accurate stock assessments and management plans to ensure that fisheries develop sustainably. Despite this, very few validated age studies have been conducted for large tropical pelagic species within the Australian region. Age and growth parameters were estimated for bigeye tuna, Thunnus obesus (Lowe, 1839), sampled from longline fisheries in the Australian region using validated techniques based on counts of annual increments. Poor increment clarity reduced the number of otoliths included in the final analysis to only 50% of the 3200 selected for reading (39–178-cm fork length). Microincrement analysis confirmed the position of the first two annual increments in these otoliths. A maximum age of 16 years was obtained, but over 80% of fish in the Australian catch were <5 years old. Growth is most rapid in the first few years of life and asymptotic length is reached at about age 9 to 10 years. The von Bertalanffy growth parameters were estimated at L∞ = 169.09, k = 0.238, and to = –1.706 for the south-west Pacific Ocean and L∞ = 178.41, k = 0.176, and to = –2.500 for the eastern Indian Ocean. These parameters were significantly different, suggesting that there is little mixing between populations in the Pacific and Indian Oceans. Length at 50% maturity for females sampled in northern Queensland was estimated to be 102.4-cm fork length.
22
Yusfiandayani, Roza, Mulyono S. Baskoro e Daniel Monintja. "IMPACT OF FISH AGGREGATING DEVICE ON SUSTAINABLE CAPTURE FISHERIES". KnE Life Sciences 2, n. 1 (1 febbraio 2015): 224. http://dx.doi.org/10.18502/kls.v1i0.107.
Testo completoAbstract (sommario):
The use of rumpon, a type of Fish Aggregating Device (FAD), has been traditional in Indonesia, particularly in eastern Indonesia waters since time immemorial (Reuter 1938; Nasution et al. 1986; Monintja 1976). The traditional tuna fishermen in Mamuju waters in the Province of South Celebes have used rumpons for a long time, although there is no record when the device was first used (Nasution et al. 1986). Any structure designed or made to attract free schooling fishes: rumpon (Indonesia), tendak (West Java), uncang (Sumatera), rompong (Sulawesi), payaos (Philippines). Local fishermen claimed that they learned how to construct the rumpon from their ancestors, but did not apply the device extensively until 1985 because of the low profitability of catching the swift swimming fishes. The use of rumpon for fishing activities has improved the effectiveness and efficiency of several fishing gear. However, the fast growing of rumpon utilization has raised a great concern on the sustainability of the fish resources. The rumpon management for responsible fisheries should consider the aspects of biology, location, environment, fishing gear, social and economic. The existing condition of rumpon has not fully understood and its usage in a responsible manner further elaboration also needed. For that purpose, the information of the past and present situation of rumpon in Indonesia will be important for further management. The main data were collected and compiled from various references, annual report of the Directorate General of Fisheries and research report of Central Research Institute for Fisheries. Additional data were made available from local fisheries agencies or related institutions. Structure of the rumpon installed in the Provinces of North Sumatera, West Sumatra, Lampung, West Java, East Java, North Celebes, Central Celebes, South Celebes, maluku and Papua are given in detail. There are 2 types of rumpon : the deep sea rumpon and shallow water rumpon. The differences among the rumpons in those areas are mostly found in material of mooring line, shape and material of float and structure of the attracting components. The mooring line is mostly made of polyethylene of 12-25 mm in diameter or nylon of 5-10 mm in diameter. There are wide variations of shape of floats. Generally they are divide into pontoon type or box shape made of steel and raft type made of bamboos. Attractors are made of coconut leaves, nipah leaves and pinag leaves. Some attractors are attached to the mooring line and the others are hung down from the float. They are operated in wide range of water depth from 20 to 1500 m. The fishing ground conditions, bottom topography and bottom configuration are among the factors considered for the rumpon design and construction. The differences in construction are mainly due to the rumpon location, target species in each area and the fishing gear applied. Keywords : fish aggregating device, rumpon, sustainable fisheries, Indonesia
23
Ladino, Felipe, Sandra Martínez, María Duarte, Natalia Vélez e Sandra Bessudo. "Monitoring of the status of eleven bony and cartilaginous fish populations in the Malpelo Sanctuary of Fauna and Flora, Colombian Pacific". Boletín de Investigaciones Marinas y Costeras 50, n. 1 (30 giugno 2021): 105–20. http://dx.doi.org/10.25268/bimc.invemar.2021.50.1.1084.
Testo completoAbstract (sommario):
To determine trends over time in the relative abundance of species prioritized in the Malpelo Fauna and Flroa Sanctuary Management Plan, underwater visual censuses were done from April 2009 to August 2019. Data were collected for five species of bonefish: bluefin trevally (Caranx melampygus), longfin yellowtail (Seriola rivoliana), yellowfin tuna (Thunnus albacares), leather bass (Dermatolepis dermatolepis) and sailfin grouper (Mycteroperca olfax), and six cartilaginous fish: spotted eagle ray (Aetobatus laticeps), silky shark (Carcharhinus falciformis), Galapagos shark (Carcharhinus galapagensis), whitetip reef shark (Triaenodon obesus), whale shark (Rhincodon typus) and scalloped hammerhead shark (Sphyrna lewini). A negative non-significant trend in abundance through time was observed for most of the evaluated species, except A. laticeps and T. obesus, which showed positive non-significant trends. The hammerhead shark (S. lewini) was the only species that showed a statistically significant decrease in abundance over time. The results of this study highlight the urgent need to establish more effective fisheries management and regulation measures that promote the conservation of important fish species, not just inside the sanctuary but also within the Tropical Eastern Pacific.
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Maunder, Mark N., John R. Sibert, Alain Fonteneau, John Hampton, Pierre Kleiber e Shelton J. Harley. "Interpreting catch per unit effort data to assess the status of individual stocks and communities". ICES Journal of Marine Science 63, n. 8 (1 gennaio 2006): 1373–85. http://dx.doi.org/10.1016/j.icesjms.2006.05.008.
Testo completoAbstract (sommario):
AbstractDespite being one of the most common pieces of information used in assessing the status of fish stocks, relative abundance indices based on catch per unit effort (cpue) data are notoriously problematic. Raw cpue is seldom proportional to abundance over a whole exploitation history and an entire geographic range, because numerous factors affect catch rates. One of the most commonly applied fisheries analyses is standardization of cpue data to remove the effect of factors that bias cpue as an index of abundance. Even if cpue is standardized appropriately, the resulting index of relative abundance, in isolation, provides limited information for management advice or about the effect of fishing. In addition, cpue data generally cannot provide information needed to assess and manage communities or ecosystems. We discuss some of the problems associated with the use of cpue data and some methods to assess and provide management advice about fish populations that can help overcome these problems, including integrated stock assessment models, management strategy evaluation, and adaptive management. We also discuss the inappropriateness of using cpue data to evaluate the status of communities. We use tuna stocks in the Pacific Ocean as examples.
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Rick, Torben, Virginia L. Harvey e Michael Buckley. "Collagen fingerprinting and the Chumash billfish fishery, Santa Barbara Channel, California, USA". Archaeological and Anthropological Sciences 11, n. 12 (21 novembre 2019): 6639–48. http://dx.doi.org/10.1007/s12520-019-00930-4.
Testo completoAbstract (sommario):
AbstractBillfish from the families Xiphiidae (swordfish) and Istiophoridae (marlins and sailfish) are large, often pelagic fishes that are highly migratory. Although some billfish have been the target of global commercial and sport fisheries for decades, prehistoric billfish foraging is relatively rare, but includes systematic swordfish (Xiphias gladius) and/or striped marlin (Kajikia audax) exploitation in the Santa Barbara Channel region of California, the Gulf of Maine, and the northern coast of Chile. While whole vertebrae, rostra, and other elements can often be identified to species, fragments of these, or other non-diagnostic elements such as fin ray spines, as well as modified bones, are difficult to determine to species-level beyond general identification as billfish or “large fish.” We performed collagen fingerprinting on modern (n = 17) and archaeological (n = 30) billfish and large tuna (Scombridae) remains from museum collections and Chumash archaeological sites in California’s Santa Barbara Channel region to test this method for determining the species of fragmentary remains. These data demonstrate that collagen fingerprinting can distinguish between the families Istiophoridae, Xiphiidae, and Scombridae, although distinguishing between species within Istiophoridae needs additional research. All but one of our archaeological specimens are from swordfish, with just one striped marlin, suggesting that the Chumash were likely encountering or targeting swordfish more frequently than other billfish species. Our study demonstrates that collagen fingerprinting is an important technique for documenting ancient billfish and other fisheries around the world.
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Tsai, Wen-Pei, Chi-Lu Sun, Sheng-Ping Wang e Kwang-Ming Liu. "Evaluating the impacts of uncertainty on the estimation of biological reference points for the shortfin mako shark, Isurus oxyrinchus, in the north-western Pacific Ocean". Marine and Freshwater Research 62, n. 12 (2011): 1383. http://dx.doi.org/10.1071/mf11010.
Testo completoAbstract (sommario):
Biological reference points (BRPs) are commonly used to assess the harvest level and stock status of marine fish populations. However, BRP estimates may be influenced by uncertainties about life-history parameters and fishing practices. The shortfin mako shark, Isurus oxyrinchus, is one of the most important by-catch species for tuna longline fisheries; however, its stock status remains poorly understood. To understand its population dynamics, the present study examined fishery statistics data and biological measurements of the shortfin mako in the north-western Pacific, and evaluated the impact of uncertainties associated with various sources of uncertainty, by using a simulation approach. The simulations indicated that BRPs are especially sensitive to changes in weight–length relationship and the growth parameters. Failure to take this into account may lead to inaccurate estimates and have serious consequences for management decision-making. To improve the accuracy of BRP estimates, biological measurements and life-history parameters should be updated regularly to account for changes in size composition and population structure. Further research could focus on increasing the sex-ratio sample size, updating the weight–length relationship and growth equations, incorporating ageing error into BRP calculations and determining BRPs by using appropriate levels of spawning-potential ratio.
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Dharmadi, Dharmadi, Mas Tri Djoko Sunarno e Isa Nagib Edrus. "PERIKANANDANASPEKBIOLOGI IKANPARI LAMPENGAN, Mobula japanica DI PERAIRANSELATAN JAWA". BAWAL Widya Riset Perikanan Tangkap 3, n. 6 (6 febbraio 2017): 369. http://dx.doi.org/10.15578/bawal.3.6.2011.369-376.
Testo completoAbstract (sommario):
Ikan pari merupakan salah satu jenis ikan yang banyak didaratkan berasal dari Selatan Jawa. Salah satu jenis ikanpari yang belum banyak dilakukan penelitian adalah ikan pari lampengan (Mobula japanica). Tujuan penelitian ini adalah untuk mengetahui tentang perikanan dan aspek biologi jenis ikan tersebut di perairan Selatan Jawa sebagai informasi dasar bagi penentuan kebijakan pengelolaan perikanan Elasmobranchii. Penelitian menggunakan metode survei yang berlangsung dari Januari hingga Desember 2010 di Pelabuhan Perikanan Samudera Cilacap-Jawa Tengah. Sejumlah 165 ikan pari yang tertangkap oleh jaring insang diamati tingkat kematangan seksual, tingkat kematangan gonad, jenis kelamin dan ukuran lebar cawannya.Wawancara dilakukan terhadap para nelayan dan nahkoda kapal yang menangkap ikan pari lampengen tersebut secara langsung dan atau oleh enumerator. Hasil penelitian menunjukkan bahwa tangkapan per satuan usaha (CPUE) ikan pari lampengan bervariasi, yakni tertinggi pada bulan Juli (22,6 kg/ hari) dan terendah pada bulan Oktober (6,6 kg/hari). Frekuensi lebar tubuh ikan pari lempengen terendah terdapat pada ukuran antara 100-140 cmdenganmodus 120 cmyang termasuk kelompokmuda, sedangkan ukuran antara 150- 200 cm dengan modus 170 cm, termasuk kelompok dewasa. Frekuensi lebar tubuh tertinggi terdapat pada ukuran antara 200-260 cmdenganmodus 230 cm. Ikan pari lempengen sedikitnya terdiri atas 3 kelompok umur dengan modus sebaran lebar tubuh masing-masing 120, 170, dan 230 cm. Hubungan lebar tubuh (y) dan panjang klasper (x)mengikuti persamaan y=0,3784e0,0131x (r2=0,85), semakin bertambah lebar tubuh semakin bertambah panjang klaspernya.Perbandingan kelamin jantan dan betina adalah tidak seimbang (1,5:1). Sebagian besar kelompok umur ikan pari lampengan yang tertangkap tergolong usia muda, yang belummencapai pertumbuhan optimum(growth over fishing). Stingray is one of the species of fish that many landed came from the South of Java. One of the species that have not many research is JapaneseDevilray (Mobula japanica). The purpose of this study was to determine fisheries and biological aspects of Japanese Devilray, Mobula japanica in Indian Ocean as basic information for managing the elasmobranches fisheries. This study was conducted from January to December 2010 in the Ocean Fishing Port of Cilacap, Central Java. A total number of 165 individu of M. japanica caught by seine net and tuna longline were observed during the sampling periods. Body wide, sex, and gonadmaturation of those fishes were analyzed. Interviewswere also done to the fisherman and fishing master. The results showed that the body width of stingrays, M. japanica had the lowest frequency between 100-140 cm with mode of 120 cm,and grouped as young fish.Other groups has body width between 150-200 cm with mode 170 cm, and grouped as adult fishes. While the frequency of the highest body width was between 200-260 cm and 230 cmmode. At least, there were 3 cohorts ofM. japanica found in this study with the body width mode of 120, 170 and 230 cm. Exponential relationship between body width (y) and claspers’ length (x) was observed forM. japanica, that expressed by equation: y=0.3784e 0.0131x (r2=0.85), that mean the more width fish body, the more increase claspers’ length. Unbalance sex ratio of 1.5:1 was observed for this fish. CPUE for M. japanica were varied between 6,6 kg/day during October and 22,6 kg/day 0n July. Most of fish caught were young fishes under their maturity stages that indicated a tendency of growth over fishing.
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Mira, Mira, e Subhechanis Saptanto. "PENGARUH KEBIJAKAN PERUBAHAN TARIF IMPOR TERHADAP KINERJA SEKTOR KELAUTAN DAN PERIKANAN". Jurnal Kebijakan Sosial Ekonomi Kelautan dan Perikanan 7, n. 1 (15 gennaio 2018): 13. http://dx.doi.org/10.15578/jksekp.v7i1.5745.
Testo completoAbstract (sommario):
Adapun tujuan dari penelitian ini adalah melihat pengaruh kebijakan perubahan tarif impor terhadap kinerja sektor kelautan dan perikanan. Data dari tabel Input dan Output dianalisis dengan menggunakan computable general equilibrium mode (CGE). Simulasi dilakukan dengan Focus Group Discussion, pertama menggunakan tarif impor yang berlaku saat ini untuk produk perikanan yaitu sebesar 5%, kedua menggunakan tarif impor 10 persen jika tarjadi peningkatan tarif, dan ketiga menggunakan tarif 0 % dimana terjadi penurunan tarif impor karena kesepakatan kerjasama regional (Masyarakat Ekonomi Asean). Akibat pemberlakukan Masyarakat Ekonomi ASEAN (kebijakan penurunan tarif impor) terhadap kinerja makro sektor kelautan dan perikanan meningkatkan pendapatan pemerintah (GDP) sebesar 0.009%, dan peningkatan ekspor 0.040%. Kebijakan penurunan tarif impor akibat pemberlakukan MEA hanya berpengaruh negatif pada indikator neraca pembayaran, dimana penurunan tarif impor menyebabkan penurunan neraca pembayaran 0.070%. Kebijakan penurunan tarif impor meningkatkan nilai tambah produk TTC, patin, kerapu, dan garam, masing-masing sebesar 0.047%, 0.004%, 0.003%, dan 0.039%. Selain itu, kebijakan penurunan tarif impor akibat pemberlakukan MEA menyebabkan ekspor TTC naik sebesar 3.367%., sedangkan impor perikanan ikan kering dan ikan olahan naik secara signifikan menjadi 11.498% dan 11.010%. Sebaliknya kebijakan peningkatan tarif impor (dalam hal ini menjadi sebesar 10%) maka membuat penurunan pada output ikan kering dan ikan olahan impor masing-masing turun adalah sebesar 18.502% dan -17.873%. Kebijakan peningkatan tarif impor malah menyebakan peningkatan input produksi untuk ikan olahan dan ikan kering dimana masing-masing sebesar 32% dan 34,5%. Dampak kebijakan peningkatan tarif impor terhadap input produk olahan selaras dengan tujuan kebijakan pengenaan tarif impor untuk meningkatkan nilai tambah komoditas, maka diharapkan pemerintah masih mengenakan tarif impor terutama untuk komoditas yang memiliki daya saing.Title: Effect of Import Tariff Change Policy On Marine and Fisheries Sector PerformanceThis research was aimed to analyze the effect of import tariff change policy on marine and fisheries sector performance. Data was collected from Input and Output tables anddata analyzed using Computable General Equilibrium method (CGE). The simulation was conducted by Focus Group Discussion approach method, first simulation using current import tariff for fisheries product 5%, secondly using import tariff of 10% if there is increase ofimport tariff, and third using tariff 0% where there is decrease of import tariff because agreement of regional cooperation ASEAN Economic Community. As a result of the implementation of the ASEAN Economic Community (import tariff reduction policy) on the macro performance of marine and fisheries sector increased government revenue (GDP) by 0.009%, and 0.040% export increase. The import tariff reduction policy due to the imposition of the MEA only negatively affects the balance of payments indicator, where the decline in import tariffs leads to a 0.070% decrease in the balance of payments. The import tariff reduction policy increases the added value of TTC (tuna alike), catfish, grouper and salt products by 0.047%, 0.004%, 0.003% and 0.039% respectively. In addition, the import tariff reduction policy due to the introduction of the MEA caused TTC exports to increase by 3.367%, while dry fish and fish processing imports increased significantly to 11.498% and 11.010%. On the contrary, the policy to increase import tariff (in this case become 10%), the decrease of dried fish and imported fishes decreased by 18.502% and -17,873% respectively. The policy to increase import tariffs led to increased production inputs for processed fish and dried fish which were 32% and 34.5%, respectively. The impact of the policy on increasing import tariffs on refined product inputs is in line with the objective of import tariff policy to increase commodity-added value, it is expected that the government still impose import tariffs, especially for competitively priced commodities.
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Pérez, Géraldine, Laurent Dagorn, Jean-Louis Deneubourg, Fabien Forget, John D. Filmalter, Kim Holland, David Itano et al. "Effects of habitat modifications on the movement behavior of animals: the case study of Fish Aggregating Devices (FADs) and tropical tunas". Movement Ecology 8, n. 1 (10 novembre 2020). http://dx.doi.org/10.1186/s40462-020-00230-w.
Testo completoAbstract (sommario):
Abstract Background Aggregation sites represent important sources of environmental heterogeneity and can modify the movement behavior of animals. When these sites are artificially established through anthropogenic actions, the consequent alterations to animal movements may impact their ecology with potential implications for their fitness. Floating objects represent important sources of habitat heterogeneity for tropical tunas, beneath which these species naturally aggregate in large numbers. Man-made floating objects, called Fish Aggregating Devices (FAD), are used by fishers on a massive scale to facilitate fishing operations. In addition to the direct impacts that fishing with FADs has on tuna populations, assessing the effects of increasing the numbers of FADs on the ecology of tuna is key for generating sound management and conservation measures. Methods This study investigates the effects of increasing numbers of FADs (aggregation sites) on the movements of tunas, through the comparison of electronic tagging data recorded from 146 individuals tunas (yellowfin tuna, Thunnus albacares, and skipjack tuna, Katsuwonus pelamis) tagged in three instrumented anchored FAD arrays (Mauritius, Oahu-Hawaii and Maldives), that differed according to their distances among neighboring FADs. The effect of increasing inter-FAD distances is studied considering a set of indices (residence times at FADs and absence (travel) times between two visits at FADs) and their trends. Results When inter-FAD distances decrease, tuna visit more FADs (higher connectivity between FADs), spend less time travelling between FADs and more time associated with them. The trends observed for the absence (travel) times appear to be compatible with a random-search component in the movement behaviour of tunas. Conversely, FAD residence times showed opposite trends, which could be a result of social behavior and/or prey availability. Conclusion Our results provide the first evidence of changes in tuna associative behavior for increasing FAD densities. More generally, they highlight the need for comparing animal movements in heterogeneous habitats in order to improve understanding of the impacts of anthropogenic habitat modifications on the ecology of wild animals.
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Townhill, Bryony L., Elena Couce, James Bell, Stuart Reeves e Oliver Yates. "Climate Change Impacts on Atlantic Oceanic Island Tuna Fisheries". Frontiers in Marine Science 8 (23 febbraio 2021). http://dx.doi.org/10.3389/fmars.2021.634280.
Testo completoAbstract (sommario):
Climate change is already affecting the distributions of marine fish, and future change is expected to have a particularly large impact on small islands that are reliant on the sea for much of their income. This study aims to develop an understanding of how climate change may affect the distribution of commercially important tuna in the waters around the United Kingdom’s Overseas Territories in the South Atlantic. The future suitable habitat of southern bluefin, albacore, bigeye, yellowfin and skipjack tunas were modelled under two future climate change scenarios. Of all the tunas, the waters of Tristan da Cunha are the most suitable for southern bluefin, and overall, the environmental conditions will remain so in the future. Tristan da Cunha is not projected to become more suitable for any of the other tuna species in the future. For the other tuna species, Ascension Island and Saint Helena will become more suitable in the future, particularly so for skipjack tuna around Ascension Island, as the temperature and salinity conditions change in these areas. Large marine protected areas have been designated around the territories, with those in Ascension and Tristan da Cunha closed to tuna fishing. Although these areas are small relative to the whole Atlantic, these model projections could be useful in understanding whether this protection will benefit tuna populations into the future, particularly where there is high site fidelity.
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AL MALIK, M. DANIE, NI PUTU DIAN PERTIWI, ANDRIANUS SEMBIRING, NI LUH ASTRIA YUSMALINDA, ENEX YUNIARTI NINGSIH e IDA AYU ASTARINI. "Short Communication: Genetic structure of Longtail Tuna Thunnus tonggol (Bleeker, 1851) in Java Sea, Indonesia". Biodiversitas Journal of Biological Diversity 21, n. 8 (21 luglio 2020). http://dx.doi.org/10.13057/biodiv/d210828.
Testo completoAbstract (sommario):
Abstract. Al Malik MD, Pertiwi NPD, Sembiring A, Yusmalinda NLA, Ningsing EY, Astarini IA. 2020. Short Communication: Genetic structure of Longtail Tuna Thunnus tonggol (Bleeker, 1851) in Java Sea, Indonesia. Biodiversitas 21: 3637-3643. Thunnus tonggol (Longtail Tuna) is an economically important fish found in Indonesia waters, however, the information regarding this fish is lacking. Known to be a neritic fish and found in shallow water, Java Sea is one of the ideal habitats for T. tonggol species. Due to high fishing rates activities in Java Sea, a better management plan to ensure the conservation and fisheries sustainability around this area is needed, especially to protect T. tonggol population. In order to complete the Indonesian tuna data, we aim to study the diversity and genetic structure of T. tonggol in Java Sea at three different locations; i.e. Semarang, Banjarmasin, and Jakarta. In this study, population genetic methods with the marker of mitochondrial DNA (mtDNA) control region were used in population structure analysis. A total of 115 specimens were collected from the fish market around the area of study locations and amplified using polymerase chain reaction (PCR) and sequenced using Sanger methods. The result showed genetic diversity (Hd) value of 0.99366, and nucleotide diversity (π) value of 0.01906. Both of these values indicated high genetic diversity. Population analyses using Analysis of Molecular Variance (AMOVA) showed nonsignificant differences between the three populations of study (mixing population), with the ΦST value of 0,00375 (p-value > 0.05). Based on this result, the fisheries management for T. tonggol in Java Sea needs to be managed as one single population management.
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Filmalter, John D., Robert K. Bauer, Fabien Forget, Paul D. Cowley e Laurent Dagorn. "Movement behaviour and fishery interaction of silky sharks (Carcharhinus falciformis) in the tropical tuna purse seine fishery in the Western Indian Ocean". ICES Journal of Marine Science, 21 giugno 2021. http://dx.doi.org/10.1093/icesjms/fsab119.
Testo completoAbstract (sommario):
Abstract The silky shark Carcharhinus falciformis regularly associates with floating objects in the open ocean, resulting in relatively high levels of bycatch in industrial tuna purse seine fisheries using drifting fish aggregating devices (FADs). This bycatch has contributed to concerns regarding the sustainability of this fishery and its impact on silky shark populations. To investigate fishery interactions, movements of 28 silky sharks (86–235 cm TL, mean = 118 cm) fitted with pop-up and archival tags in the western Indian Ocean, between 2010 and 2012, were examined. Monthly overlap between probability surfaces of sharks and two fishery metrics (FAD-tuna catches and FAD positions) were calculated. Vertical habitat use overlapped almost entirely with operational gear depth. Horizontal movements were extensive (3–5024 km) and covered large areas of the western Indian Ocean. Monthly overlap with FAD distributions was consistently high (64.03–100%) highlighting the need for compliance with FAD design regulations to avoid entanglement. Monthly overlap with tuna catches was more variable (8.43–51.83%). The observed movement patterns suggest static spatial management measures would be have limited conservation impact, however dynamic approaches could be appropriate. Limiting fishery activities directly will likely have the greatest conservation outcomes for silky sharks in the purse seine fishery.
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Receveur, Aurore, Valerie Allain, Frederic Menard, Anne Lebourges Dhaussy, Sophie Laran, Andreas Ravache, Karen Bourgeois et al. "Modelling Marine Predator Habitat Using the Abundance of Its Pelagic Prey in the Tropical South-Western Pacific". Ecosystems, 10 agosto 2021. http://dx.doi.org/10.1007/s10021-021-00685-x.
Testo completoAbstract (sommario):
AbstractUnderstanding the ecological mechanisms underpinning distribution patterns is vital in managing populations of mobile marine species. This study is a first step towards an integrated description of the habitats and spatial distributions of marine predators in the Natural Park of the Coral Sea, one of the world’s largest marine-protected areas at about 1.3 million km2, covering the entirety of New Caledonia’s pelagic waters. The study aims to quantify the benefit of including a proxy for prey abundance in predator niche modelling, relative to other marine physical variables. Spatial distributions and relationships with environmental data were analysed using catch per unit of effort data for three fish species (albacore tuna, yellowfin tuna and dolphinfish), sightings collected from aerial surveys for three cetacean guilds (Delphininae, Globicephalinae and Ziphiidae) and foraging locations identified from bio-tracking for three seabird species (wedge-tailed shearwater, Tahiti petrel and red-footed booby). Predator distributions were modelled as a function of a static covariate (bathymetry), oceanographic covariates (sea surface temperature, chlorophyll-a concentration and 20 °C-isotherm depth) and an acoustically derived micronekton preyscape covariate. While distributions were mostly linked to bathymetry for seabirds, and chlorophyll and temperature for fish and cetaceans, acoustically derived prey abundance proxies slightly improved distribution models for all fishes and seabirds except the Tahiti petrel, but not for the cetaceans. Predicted spatial distributions showed that pelagic habitats occupied by predator fishes did not spatially overlap. Finally, predicted habitats and the use of the preyscapes in predator habitat modelling were discussed.
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Brophy, Deirdre, Naiara Rodríguez-Ezpeleta, Igaratza Fraile e Haritz Arrizabalaga. "Combining genetic markers with stable isotopes in otoliths reveals complexity in the stock structure of Atlantic bluefin tuna (Thunnus thynnus)". Scientific Reports 10, n. 1 (7 settembre 2020). http://dx.doi.org/10.1038/s41598-020-71355-6.
Testo completoAbstract (sommario):
Abstract Atlantic bluefin tuna (Thunnus thynnus) from the two main spawning populations in the Mediterranean and Gulf of Mexico occur together in the western, central and eastern Atlantic. Stock composition of catches from mixing areas is uncertain, presenting a major challenge to the sustainable management of the fisheries. This study combines genetic and chemical markers to develop an integrated method of population assignment. Stable isotope signatures (δ13C and δ18O) in the otolith core of adults from the two main spawning populations (adult baselines) showed less overlap than those of yearlings (12–18 months old) from western and eastern nursery areas suggesting that some exchange occurs towards the end of the yearling phase. The integrated model combined δ18O with four genetic markers (SNPs) to distinguish the adult baselines with greater accuracy than chemical or genetic markers alone. When used to assign individuals from the mixing areas to their population of origin, the integrated model resolved some (but not all) discrepancies between the chemistry and genetic methods. Some individuals in the mixing area had otolith δ18O values and genetic profiles which when taken together, were not representative of either population. These fish may originate from another Atlantic spawning area or may represent population contingents that move away from the main spawning areas during the first year of life. This complexity in stock structure is not captured by the current two-stock model.