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The closed cycle aquaculture of Atlantic Bluefin Tuna in Europe: current status, market perceptions and future perspectives
Abstract and Figures
To develop an approach to the sustainable production of Atlantic Bluefin Tuna (Thunnus thynnus) in Europe, the EU and the private sector have started funding research stations and commercial enterprises around the Mediterranean region to close the life cycle of Atlantic Bluefin Tuna (ABT), in the hopes of eventually producing commercial quantities of hatchery-bred fingerlings for farming purposes. To date, hatchery projects are operational or underway in Spain, Malta, Italy, Greece, Egypt, and Turkey. Several of these projects have had major breakthroughs and have successfully started producing small quantities of ABT fingerlings.
Despite these successes, the majority of these projects face a number of challenges that continue to limit the production of fingerlings in commercial quantities. These challenges include a shortage of eggs, early floating and sinking deaths in larvae, cannibalism, wall collisions, and transfer mortality. Each of these challenges is discussed in this literature review and a number of solutions, often drawn from the latest EU and Japanese research, are presented. Solutions include improved broodstock management, modifications in the general tank setup, adjustments in the use of life feeds and an updated protocol for the harvesting and transferring of juvenile tuna. With these improvements in place, the only major remaining challenge is transfer mortality after fingerlings are moved to grow-out cages. When looking at Japan we see that their sector has already overcome these last challenges and is now producing significant quantities of Pacific Bluefin Tuna (PBT) fingerlings, approximately 500,000 pieces annually. Despite this positive outlook, most of the projects working on ABT in Europe seem to be closing down or halting production.
This report also assesses the market perception of hatchery produced ABT with a focus on sustainability issues. Most previous definitions of sustainable tuna do not take aquaculture activities into account, particularly not the closed cycle aquaculture of tunas. For these reasons, this report has provided an updated definition. Additionally this report found that seafood buyers and other stakeholders have difficulties distinguishing between products from capture-based fisheries and fattening operations that use wild seed stock, and products originating from closed cycle aquaculture. Furthermore the main concerns of buyers when buying tuna from aquaculture are quality, sustainability and feed origin.
With the closed cycle aquaculture of ABT, the European Union is in the unique position to solve a number of environmental concerns while developing an enormous economic opportunity. However while the sector for PBT in Japan is starting to flourish, the projects in Europe seem to be having a harder time. To ensure a well-coordinated and sustainable approach, to maximize the potential of this opportunity, this report concludes with the proposed development of a Masterplan for the Sustainable Closed Cycle Aquaculture of Atlantic Bluefin Tuna in Europe. This masterplan focuses on financial support mechanisms for the private sector, emphasis on the development of sustainable artificial feeds, clear and simplified rules and regulations for the sector including a strong offshore approach for grow-out farms and a mandatory uniform traceability system, a training component to ensure the economic viability and sustainability of grow-out farms and finally a strong marketing component which will put sustainable European produced ABT on the map.
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... Tuna species are of great economic import because of the high international market demand for their meat (EFSA, 2009b;FAO, 2020). Increases in the popularity of sushi and sashimi as a luxury item in Japanese and international cuisine post-World War II has led to an exponential increase in demand for bluefin tuna, the preferred source for these dishes (Van Beijnen, 2017). Atlantic bluefin tuna (ABFT; Thunnus thynnus) is now officially the most sought-after fish in the world (Partridge, 2013;Van Beijnen, 2017). ...
... Increases in the popularity of sushi and sashimi as a luxury item in Japanese and international cuisine post-World War II has led to an exponential increase in demand for bluefin tuna, the preferred source for these dishes (Van Beijnen, 2017). Atlantic bluefin tuna (ABFT; Thunnus thynnus) is now officially the most sought-after fish in the world (Partridge, 2013;Van Beijnen, 2017). ...
... In 2017, only 66.6% of tuna stocks were fished at biologically sustainable levels (FAO, 2020). Amidst growing global concerns about food source sustainability, interest has grown regarding closed-cycle tuna aquaculture (i.e., farming the complete fish life cycle from spawning and hatching until slaughter) (Naylor and Burke, 2005;Metian et al., 2014;Van Beijnen, 2017). Domestication of ABFT, with captive production of eggs and juveniles, would aid conservation efforts by reducing the number of wild-caught tunas. ...
There is an increased demand for tuna meat to supply the growing global sushi and sashimi market. Current methods to farm tunas, especially Atlanic bluefin tuna (ABFT; Thunnus thynnus), are unsustainable. This is driving a movement towards closed-cycle ABFT aquaculture, i.e., farming tuna from spawning and hatching to slaughter on land, to try and meet the demand for these fish. Tunas are not domesticated species and thus face different challenges in terms of closed-cycle aquaculture when compared to other farmed fish species. Tunas also possess unique physiological traits such as regional endothermy and ram ventilation which affect their needs and how they are farmed. No current global standards exist to measure or monitor ABFT welfare in captivity, because there are many unknown factors surrounding ABFT welfare in intensive aquaculture beings. There is a need to conduct studies which measure the baseline physiological parameters of ABFT in closed-cycle systems. Issues such as manipulation of breeding cycles, tank design, and slaughter procedures need attention and further research before such welfare indicators can be established. Stress is an overarching concern for animal welfare. In particular, pre-slaughter crowding and stress negatively affects the quality of the meat produced due to lactic acid build up in the red muscle. Further research needs to be conducted throughout all life stages in terms of both animal welfare implications and commercial viability of intensively farmed ABFT.
... Croatian farmed tuna is sold mainly on the Japanese sushi-sashimi market and generally has a lower quality and a lower price than large farmed tuna [19], although according to [9], the fat content of farmed juveniles can be very high, which could lead to higher prices on the Japanese market. In 2016, farmed ABFT from Croatia (ToroCro Maguro, Sashimigrade) won the Superior Taste Award [39]. The award-winning Croatian tuna is an example of how rearing tuna from the juvenile stage onwards can be very profitable even with small tuna sizes due to the high fat content. ...
... In 2022, there were 69 ABFT farms with a maximum potential capacity of 71,440 t: Italy, 18, 17,700 t; Malta, 8, 13,800 t; Croatia, 4, 7092 t; Morocco, 4, 6600 t; Turkey, 6, 6440 t; Spain, 11, 6002 t; Tunisia, 6, 5000 t; Cyprus, 3, 3000 t; Greece, 2, 2100 t; Egypt, 1, 1800 t; Libya, 3, 1800 t; Albania, 1, 500 t; and Portugal, 2, 500 t [16]. According to [39], in 2017 there were 54 ABFT farming companies with 62 farms and a maximum potential capacity of 54,000 t, mostly distributed in clusters (Cartagena in Spain, Naples in Italy, and Zadar in Croatia) ...
... There is also a tendency for most ICCAT member states to under-report their catches to ICCAT and FAO in order to support their national finishing fleets. When they under-report landings, they also under-report catch-based aquaculture production levels to maintain consistency in reporting figures [39]. ...
Atlantic bluefin tuna (Thunnus thynnus) is the most important tuna species in Mediterranean tuna fishery and a valuable commodity on the global fish market. Croatia is a pioneer in tuna farming in the Mediterranean and the only country that has the exclusive right to farm wild-caught juvenile tuna (8 to 30 kg). This paper identifies key challenges to the sustainability of current farming and fattening practices, primarily economic and environmental, and possible solutions to overcome these challenges. This paper analyses data on tuna catch and aquaculture production (FAO FishStatJ and EU-Eurostat database) and updates the latest literature on farming practices, production challenges related to biotechnical, economic and environmental issues, the market and current legislation in Croatia, as well as fattening in other Mediterranean countries. Tuna capture-based aquaculture is attractive to investors because it promises high returns, but the sustainability of intensive tuna farming and fattening is questionable and raises many ethical issues. Tuna farming and fattening relies on wild fish for stocking and feeding, and further expansion of tuna farming and fattening is limited by the size of wild tuna and small fish populations. To meet the growing global demand for tuna and to conserve wild tuna stocks, further investments are needed. The knowledge gained in Croatian tuna farming is valuable for future sustainable close-cycled tuna farming in the Mediterranean. Due to its good environmental status, the availability of small pelagic fish, the availability of a highly qualified and well-organised labour force, the good cooperation between producers and researchers, and the application of modern farming technologies, ABFT farmed in Croatia have high quality and a good reputation on the market. The main weakness of Croatian tuna farming is that the entire industry is dependent on the Japanese market, but this can be overcome by the possibility of product diversification for new markets, including the tourism industry.
... Atlantic bluefin tuna (ABT, Thunnus thynnus, L.) is a high-value species on the market. In recent years, ABT juveniles have been captured from the wild and fattened using bait fish in so-called sea ranches [1]. Recently the production cycle of ABT has been closed, however low survival at larval stages dictates this is still far from commercial production [1,2]. ...
... In recent years, ABT juveniles have been captured from the wild and fattened using bait fish in so-called sea ranches [1]. Recently the production cycle of ABT has been closed, however low survival at larval stages dictates this is still far from commercial production [1,2]. As in other bluefin tuna species, ABT has a very sensitive larval stage characterized by several problematic issues including size variation, low swim bladder inflation rates and skeletal anomalies [3,4]. ...
Selenium (Se) is an essential trace element for fish with more than 40 selenoproteins identified, many exhibiting antioxidant functions. This study investigated the effect of dietary Se supplementation on physiological parameters, selenoprotein and antioxidant enzyme gene expression in Atlantic bluefin tuna (ABT, Thunnus thynnus) larvae. First-feeding ABT larvae were divided into triplicate groups and fed rotifers Brachionus rotundiformis enriched with five different levels of Se (0, 3, 10, 30, and 100 µg Se·L⁻¹) until 14 days after hatching. Both rotifers and ABT larvae effectively accumulated Se achieving maximum levels in the Se100 treatment (30.05 μg Se·g⁻¹ and 194 ± 38 μg Se·g⁻¹ dry mass, respectively). Larvae showed highest total length when fed Se3 rotifers, whereas flexion index was highest in larvae fed Se10. Selenium supplementation increased the gene expression of selenoproteins gpx1, msrb1, trxr2, selenom, selenop, and selenoe compared to the non-supplemented control (Se0), but only marginal differences were detected between supplementation levels. In contrast, expression of the antioxidant enzymes cat and sod1 were lowest in larvae fed Se100. To conclude, non-Se-enriched rotifers may be suboptimal for first feeding ABT larvae, which showed improved selenoprotein and antioxidant gene expression when fed a diet containing 4.42 μg Se·g⁻¹ dry mass.
... Sama halnya pada benih tuna sirip biru Pasifik (PBT) Thunnus orientalis, mortalitas yang tinggi karena perkembangan fungsi mata lebih lambat dibandingkan perkembangan kecepatan berenang (Matsumoto et al., 2011). Produksi benih tuna-sirip biru Atlantik (ABT) Thunnus thynnus, di Uni Eropa juga menghadapi kendala yang sama sehingga sintasan benih pada umur 30 hari setelah menetas paling tinggi 0,44% (Beijnen, 2017). ...
... Memasuki stadia benih, ABT mengalami perubahan sosial yaitu mulai bergerombol dan setelah bergerombol, kanibalisme mulai menurun (Beijnen, 2017) dan ini merupakan sifat ikan tuna pada umumnya. Kondisi lingkungan juga dapat menurunkan sifat kanibalisme, seperti bentuk bak, intensitas cahaya, kepadatan benih, serta penyortiran berdasarkan ukuran secara regular. ...
Sintasan larva hingga benih ikan tuna sirip kuning di hatchery sudah meningkat dari 0,05% menjadi 0,20%-0,50%. Namun mortalitas pada pemeliharaan tahap berikutnya sangat tinggi. Kematian benih karena menabrak dinding bak/jaring, berkaitan dengan kebiasaan renang dan kondisi lingkungan. Oleh karena itu, riset pendederan ini difokuskan pada pengamatan kebiasaan berenang dan pemangsaan, serta kondisi lingkungan. Wadah yang digunakan adalah enam buah bak fiberglass reinforced plastic (FRP) diameter 2,7 m; ketinggian 1,0 m; dan diisi dengan air laut 5 m3. Hewan uji berupa benih ikan tuna sirip kuning dengan panjang total 29,82 ± 2,51 mm hasil produksi dari hatchery, sebanyak 50 ekor benih per bak. Perlakuan dalam riset adalah perbedaan sistem pemeliharaan, yaitu: (A) indoor dan (B) outdoor dengan tiga ulangan dan lama penelitian 21 hari. Pakan yang digunakan adalah ikan segar berupa benih bandeng yang dimatikan dan ikan teri dengan panjang total 15-25 mm dan ikan cincang (minced fish). Frekuensi pemberian pakan adalah enam kali per hari dan diberikan secara satiasi. Parameter meliputi suhu, oksigen terlarut, dan intensitas cahaya diukur setiap hari. Hasil riset menunjukkan bahwa sintasan dalam pendederan sistem indoor sebesar 20,0 ± 4,0% lebih tinggi (P<0,05) dibanding dengan sistem outdoor (6,7 ± 5,0%). Pertumbuhan bobot spesifik 12,4% hari-1 pada sistem indoor lebih baik dibandingkan sistem outdoor yang hanya 9,8% hari-1 (P<0,05). Dari hasil penelitian ini dapat disimpulkan bahwa intensitas cahaya dan suhu yang lebih stabil pada pendederan sistem indoor memberikan sintasan dan pertumbuhan yang lebih baik dibandingkan pada sistem outdoor. Namun demikian, disarankan bahwa pendederan dalam bak FRP sebaiknya tidak lebih dari dua minggu agar diperoleh sintasan yang lebih tinggi dan selanjutnya dipindahkan ke karamba jaring apung (KJA).The survival rate of reared yellowfin tuna from larvae to juvenile stages in hatchery has been improved from 0.05% to 0.20%-0.50%. Unfortunately, the fish’s mortality rate during the nursery phase is still very high. Unpredicted swimming and feeding behaviors have resulted the reared juveniles to uncontrollably hit the tank wall and died. Therefore, this research was carried out to study the swimming and feeding habits of yellowfin tuna juveniles and its response to different rearing environments. Six fiberglass reinforced plastic (FRP) tanks with a diameter of 2.7 m, height 1.0 m, and filled with 5 m3 of filtered sea water were used in the study. Yellowfin tuna juveniles with an average total length of 29.82 ± 2.51 mm were harvested from a hatchery and placed into each tank at a density of 50 fish tank-1. The treatments applied were two nursery systems: (A) indoor and (B) outdoor system with three replicates. The rearing treatment lasted for 21 days. Raw fish was given as feed consisting of mixed of defrosted milkfish fry and small anchovy with total length ranged between 15-25 mm as well as minced fish meat. Feed was given six times per day at satiation. The observed parameters were temperature, dissolved oxygen, and light intensity measured daily. The results showed that the survival rate of juvenile in the indoor system was 20.0 ± 4.0%, which was higher (P<0.05) than that of the outdoor system (6.7 ± 5.0%). Weight specific growth rate of fish reared in the indoor system was 12.4% day-1 which was better than that of the outdoor system which was only 9.8% day-1 (P<0.05). This research concludes that a stable light intensity and water temperature in the indoor nursery system gives better survival and growth rate on yellowfin tuna juvenile. Nevertheless, this research recommends that the nursery phase of yellowfin tuna juvenile in FRP tank should be carried out not more than two weeks in order to produce a higher survival rate and then transferred to floating net cages.
... It is, therefore, puzzling why NCM selected to concentrate its domestication R&D on the carnivorous pelagic tuna (Thunnus thynnus and Thunnus albacares). As explained above, high production costs and expected fall in prices are expected to make the large-scale production of tuna and other super carnivores unsustainable and unprofitable, even had their domestication succeeded (e.g., Zertuche-González et al. 2008;Van Beijnen 2017;Teletchea et al. 2021). ...
An upbringing typical of the Israeli countryside, and the statutory military service, were followed by academic education, which concluded with a PhD in oceanography and marine biology at the Scripps Institution of Oceanography, University of California, San Diego. During that time, I started a family. With my wife and two sons, we returned to Israel in early 1986, right after graduation. A research position ensued for over three decades at the Israeli National Center for Mariculture in Eilat, where I pursued my passion for sustainable aquaculture. My education in field-crop agriculture, algal physiology and growth dynamics, marine biology, photosynthesis, and biological oceanography, prepared me for an exciting career. It involved several oceanographic research cruises in several oceans and seas, visits to all seven continents, and experimental and conceptual research programs in several fields of marine biology, biological oceanography, and genuinely sustainable aquaculture. Over the years, I visited as a sabbatical visitor and other capacities universities and research institutes worldwide. My main legacy is the establishment of the role of algae in aquaculture, particularly as a key component in IMTA (integrated multi-trophic aquaculture).
... Atlantic bluefin tuna (ABT, Thunnus thynnus, L.) is a species with high market value although its closed aquaculture is currently inefficient and far from large-scale commercial production with low survival of larval stages, (De la Gandara et al., 2016;Van Beijnen, 2017). In order to optimize the ABT production cycle, further knowledge of the nutritional requirements of the species is pivotal, and understanding biological mechanisms of nutrient assimilation in larvae is a key area. ...
Taurine appears to be a crucial nutrient for teleosts, especially top predator species such as Atlantic bluefin tuna (Thunnus thynnus, L.; ABT). While dietary taurine supplementation has been highly recommended, there is a lack of studies on taurine assimilation and biosynthesis for this iconic species. The present study aims to provide insight into the molecular mechanisms involved in taurine biosynthesis and transport in ABT by studying tissue distribution and ontogenetic development of expression of cysteine dioxygenase (cdo), cysteine sulfinic acid decarboxylase (csad), 2-aminoethanethiol dioxygenase (ado) and taurine transporter (tauT) in response to graded levels of dietary taurine supplementation. The full open reading frame (ORF) for cdo and partial sequences for csad, ado and tauT were obtained, with the translated polypeptides being 202, 176, 166 and 324 amino acids, respectively. All three showed characteristics such as cupin motifs in Cdo and predicted N-glycosylation sites in Taut that are common to these genes in other species. Phylogenetic analysis showed that the ABT sequences clustered with sequences of other teleosts, and separately from mammals and molluscs. Tissue distribution varied, with adipose tissue, kidney, white muscle and testis/brain showing highest expression of cdo, csad, ado and tauT, respectively. Whole larvae expression of csad peaked at 15 dah, whereas the other genes generally increased throughout development to show highest expression at 25 dah. The nutritional trial was carried out by feeding ABT larvae from mouth opening to 14 days after hatching (dah) with rotifers (Brachionus rotundiformis) enriched with 4 different levels of taurine: 0.0 (tau0), 0.5 (tau0.5), 1.0 (tau1), and 2.0 g taurine per 10⁶ rotifers (tau2). Rotifers effectively accumulated taurine with ABT larvae fed on treatment tau2 attaining the highest concentration of taurine. However, ABT larvae fed tau1 displayed higher growth and survival, and flexion index at 14 dah, than larvae fed the other taurine levels. Larvae fed tau1 also showed generally higher expression of tauT and cdo and digestive and antioxidant enzyme genes. While this study showed that larval ABT express taurine metabolism genes, suggesting possible synthesis that could contribute to the taurine pool in the fish, larval performance was enhanced by a level of dietary taurine (3.7 mg taurine g⁻¹ rotifer) supplied by enrichment of rotifers at 1 g taurine per 10⁶ rotifers.
The tuna cages are a vortex, a maelstrom of giants. In the deep blue water the shoal of bluefin circles slowly around an invisible axis somewhere in the middle of the cage of circular nets. There must be many dozens of them, in a deep whirlpool of fish that reaches to the bottom of the sea. They inch forward, their tailfins swishing majestically through the water. The stately calm disappears as soon as the engine of the boat with fresh fish comes within earshot. Once the sardines, herring and cuttlefish are thrown over the raised edge that keeps the nets of the circular cage afloat, the surface of the water transforms into a whirling mass of dorsal fins, splashing foam and gaping jaws into which the fish disappears. Feeding time at the tuna farm. Tuna is always hungry.
Elongation of very long-chain fatty acid 4 (Elovl4) proteins are involved in the biosynthesis of very long-chain (>C24) fatty acids and in many teleost fish species they are key enzymes in the pathway for the production of docosahexaenoic acid (DHA; 22:6n-3) from eicosapentaenoic acid (EPA; 20:5n-3). Therefore, Elovl4 may be particularly important in Atlantic bluefin tuna (ABT; Thunnus thynnus) characterised by having high DHA to EPA ratios. The present study cloned and characterised both the function and expression of an elovl4 cDNA from ABT. The Elovl4 had an open reading frame of 915 base pairs encoding a putative protein of 304 amino acids. Alignment and phylogenetic analyses indicated that the Elovl4 isoform identified in the present study was an Elovl4b. Functional characterisation demonstrated that the Elovl4b enzyme had elongase activity towards all the polyunsaturated fatty acid (PUFA) substrates assayed. The ABT Elovl4b contributed to DHA biosynthesis by elongation of EPA and DPA to 24:5n-3, the latter being desaturated to 24:6n-3 by the action of fads2 (Δ6 desaturase). Additionally, the ABT Elovl4b has a role in the biosynthesis of very long-chain PUFA up to C34, compounds of key structural roles in neural tissues such as eye and brain, which had high levels of elovl4b transcripts. Surprisingly, while the relative expression of fads2, required for the production of DHA from EPA, was increased in liver of ABT fed a diet with reduced levels of EPA and DHA, expression of elovl4b was reduced. Results indicated that ABT has enzymes necessary for endogenous production of DHA from EPA and demonstrate that Elovl4b can effectively compensate for absence of Elovl2.
The Mediterranean Sea has been defined “under siege” because of intense pressures from multiple human activities; yet there is still insufficient information on the cumulative impact of these stressors on the ecosystem and its resources. We evaluate how the historical (1950–2011) trends of various ecosystems groups/species have been impacted by changes in primary productivity (PP) combined with fishing pressure. We investigate the whole Mediterranean Sea using a food web modelling approach. Results indicate that both changes in PP and fishing pressure played an important role in driving species dynamics. Yet, PP was the strongest driver upon the Mediterranean Sea ecosystem. This highlights the importance of bottom-up processes in controlling the biological characteristics of the region. We observe a reduction in abundance of important fish species (~34%, including commercial and non-commercial) and top predators (~41%), and increases of the organisms at the bottom of the food web (~23%). Ecological indicators, such as community biomass, trophic levels, catch and diversity indicators, reflect such changes and show overall ecosystem degradation over time. Since climate change and fishing pressure are expected to intensify in the Mediterranean Sea, this study constitutes a baseline reference for stepping forward in assessing the future management of the basin.
The yellowfin tuna (Thunnus albacares) (YFT) exhibits strong potential as a candidate species for full-life-cycle aquaculture. The Inter-American Tropical Tuna Commission (IATTC) has maintained a spawning population and studied the reproductive biology and early life history of YFT for research purposes at its Achotines Laboratory, Republic of Panama, since 1996. The broodstock YFT have spawned in land-based tanks at near-daily intervals as long as water temperatures have exceeded 23.3 °C. Courtship and spawning behaviors and the effects of physical and biological factors on spawning dynamics have been studied, and growth and survival rates of broodstock fish have been estimated. Experimental investigations of the early life history from the egg stage to 115 days after hatching (dah) have been conducted. The larval and early-juvenile stages are characterized by fast growth, high metabolic requirements, and high mortality. The refinement of rearing protocols that increase survival in the yolksac and first-feeding larval stages, and the development of improved artificial diets and sea cage rearing of juveniles, will hold the key to successful development of full-life-cycle aquaculture of YFT.
Wild southern bluefin tuna caught in the Great Australian Bight off Australia’s southern coast are ranched to add quality and value to products sold both domestically and internationally. Since its beginning in 1990, the Australian southern bluefin tuna ranching industry has grown steadily, and is a valuable sector of Australia’s aquaculture industry. To become the economic success that it is today, the southern bluefin tuna ranching industry has overcome a number of challenges. To remain economically and ecologically viable, however, the industry must continue to build understanding of tuna stocks and biology while focusing on innovative husbandry methods including widespread replacement of baitfish feed with manufactured diets.
Understanding the reproductive biology of Atlantic bluefin tuna (ABFT) is important to both managing its fishery and developing hatchery technologies to close its life cycle in aquaculture. Globally, ABFT is comprised of two populations, the eastern and western stocks, with known breeding areas in the Mediterranean Sea and the Gulf of Mexico, respectively. Gametogenesis takes place during spring and early summer, and spawning usually occurs from May to July, coinciding with the rise of water temperature. Females display an asynchronous ovarian development, typical of a batch spawner. Comparing the endocrine-reproductive cycle in wild and captive ABFT led to the development of a hormone-based therapy to induce spawning in captive broodstock. While captivity affects gametogenesis in ABFT, at least some of the captive fish spawn spontaneously, which can be enhanced and prolonged using hormonal induction. Massive spawning of captive ABFT enabled the first aquaculture production of marketable fish, demonstrating the biological feasibility of this industry. Current research on hormonal regulation of its puberty may lead to the use of smaller ABFT broodstock, simplifying their husbandry and management. This, together with the establishment of land-based broodstock operations, will enable efficient and cost-effective on-demand and year-round production of ABFT seeds to drive the consistent farming of this fish.
Advances in Tuna Aquaculture: From Hatchery to Market provides detailed overviews on the current status of tuna fisheries, fattening, and farming practices, as well as advances in closed-cycle tuna aquaculture. Contributors are renowned scientists, internationally recognized as authorities in their fields. This book addresses all basic and applied aspects of tuna aquaculture, presenting and discussing the global status of tuna fisheries, reproduction, broodstock management, spawning, larval rearing and early developmental stages including nursery and grow out methods. It presents incorporates the most comprehensive and updated data, statistics, and trends in tuna fisheries and aquaculture, covering and addresses a variety of topics ranging fromfrom endocrinology, nutrition, diseases, and genetics to economics and markets. It covers describes recent up-to-date progress on tuna aquaculture and hatchery development. It also provides a synopsisn overview of the challenges presently confronted by tuna aquaculturists,facing tuna aquaculture and and offers innovative views on the challengesbottle-neck issues faced by the industry with the current shift from fisheries to fattening to closed-cycle aquaculture. This is the first book to encompass all aspects related to the tuna aquaculture industry, and merges them into a state-of-the-art compendium that will serve as seminal reference for students, researchers, and professionals working with tuna biology, fisheries, and aquaculture worldwide. Incorporates and reviews the most recent information on tuna fisheries and aquaculture. Presents the most innovative production technologies in tuna aquaculture, from hatchery to market. Includes important information on tuna, derived from industry experience and academic research on larval rearing technology and grow out operations. Encompasses and discusses key topics such as genetics, diseases, nutrition, endocrinology, and reproduction, as well as developments, challenges, and future opportunities in tuna aquaculture. Provides the latest scientific methods and technologies to maximize efficiencies and production. Presents the independent and collective assessments, viewpoints, and visions of various scientists, all internationally recognized as authorities in the field.
The development of Atlantic bluefin tuna farm production in the Mediterranean, which relies on collecting tunas from the ocean, has created a number of recent challenges to managers of the wild stock. As a result, additional monitoring requirements have being imposed on fishing fleets and farming operations. Although the development of farming may have contributed to higher catches of tuna in the Mediterranean and may have shifted fishing toward more purse seine caught fish, such tendencies began before farming started in earnest. Since farming started, however, there has been a decline in the proportion of tuna harvested by longline fleets. Such changes in the mix of gears used to harvest tuna may have led to changes in the composition and amount of bycatch. The possible ecosystem effect of such changes in fishing practices are still to be evaluated and can only partially be associated with the development of farming. Other reported effects of farming include changes in ecosystem balance related to the shift in tuna diet of farmed fish from wild to human-provided, cages acting as fish aggregating devices and impacts of excess feed and tuna waste on benthos from cages set in relatively shallow areas. Ultimately, the major challenges remaining are to reduce the dependence which farming has on wild-caught tuna and seafood-based farm diets. Overcoming such challenges would benefit not only the farming industry but also the sustainability of the wild stock.
The current status of tuna fiseries, fattening and farming practices, as well as advances in closed-cycle tuna aquaculture, are summarized. The emergence and expansion of tuna fattening and farming activities during the last four decades have led to a shift from traditional fisheries toward aquaculture. This change is entirely reshaping the tuna fishery industry and the management of their stocks worldwide. Tuna fattening and farming operations still rely primarily on wild-caught juveniles that are fattened using small pelagic fish, blurring the line between fisheries and aquaculture and merging these activities to the point that it is no longer possible to analyze them separately. Progress in fattening operations has been limited to improved management and decreased mortalities during the capture, towing, transferring, and feeding stages of the tuna in cages. However, tuna aquaculture is now rapidly changing due to remarkable progress in closed-cycle tuna aquaculture production through advancements in broodstock maturation, spawning, larval rearing, and juvenile production technologies. Indeed, following the pioneering achievement of closing the life cycle of the Pacific bluefin tuna (PBFT) in Japan, researchers the world over are now making significant progress in hatchery technology. Closing their life cycle and the development of ecologically and economically efficient feeds that meet the specific nutritional requirements of tuna are required to ensure the future of tuna production and the conservation of tuna species. Collective efforts by researchers, academics, and the global industry are making it possible to achieve these goals.
The production of hatchery reared southern bluefin tuna (SBFT, Thunnus maccoyii) fingerlings is needed for further sustainable expansion of production from the Australian tuna aquaculture industry. Clean Seas Tuna Ltd (CST) has pioneered progress toward closing the SBFT life cycle in captivity since broodstock held in an onshore tank system first spawned in 2008. Since then, CST has collaborated with key Australian research agencies on a range of scientific programs supported by Australian Seafood Cooperative Research Centre (SfCRC). These investigations have developed a preliminary SBFT propagation husbandry protocol that has been implemented at CST Arno Bay hatchery in South Australia, including the techniques for broodstock management and induced spawning in the land-based facility, as well as larvae and juvenile fish rearing until the end of the nursery stage. Some major obstacles still remain unsolved for SBFT, such as unreliable egg supply from captive broodstock, low survival in late larval and early juvenile stages, sub-optimal weaning diets, cannibalism, wall collisions, and a high level of handling stress following transfer of fingerlings to ponds and sea cages. However, significant knowledge and hands-on experience toward closing the SBFT life cycle have been achieved.
Among Mediterranean fishes, the Atlantic bluefin tuna (ABFT, Thunnus thynnus) is remarkably well adapted to its habitat. Many consider it and its relatives to be physiological wonders, owing to their warm-bodied nature and capacity for rapid growth and fast swimming. ABFT today are threatened by the one thing to which this species has not been able to adapt, overfishing. The superb taste of the ABFT’s flesh has made it a prized target for human consumption in the Mediterranean world, over the ages. Europe is rich in historic accounts and traditions involving human–tuna interactions. As one of the most valuable fishery species in the world, the ABFT has attracted international interest in assuring its permanence and sustainability of its stocks. Attention to both wild and ranched ABFT populations has accelerated since the late 1990s, and significant strides have been made toward true aquacultural farming to replace ranching of wild-caught animals. Building on previously successful aquaculture models, European aquaculture is now on the verge of closing the life cycle for this species. Significant advances have also been made, through collaborative research, on other fronts also related to tuna aquaculture. This chapter provides an up-to-date and comprehensive account of the state-of-the-technology in tuna aquaculture in Europe.
The economic aspets of tuna production significantly vary when shifting from the wild fishery to aquaculture. The farming industry has made significant biological and technical advances in recent years, but is still strongly dependent on catches as a source of livestock. However, the differences in production, management, and market orientation make tuna ranching a source of supply radically different, from an economic point of view, to wild fisheries and general aquaculture. Global tuna production is driven by two main markets, the traditional canned tuna market mainly supplied by white meat species and the Japanese sushi and sashimi market, in which red meat species are dominant. This chapter describes the sources of tuna supply for the world markets and considers the economic management of tuna farming, describing the production stages and cost structure. Finally, the evolution of the market for tuna species is presented with focus on bluefin and the Japanese market. Issues affecting public opinion with regards to tuna consumption and their effects on health and the environment are discussed.