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This article examines, from the perspective of international institutional law, the variety of procedural problems which arose following an online vote by secret ballot taken by the Indian Ocean Tuna Commission (IOTC) in 2021. By providing a detailed case-study of this novel instance of practice and the challenges it represents, this article aims to contribute to a better understanding of the institutional governance and procedural legal framework of regional fisheries management organizations (RFMO s). It first analyses the vote and the challenge to its validity. This article then constructs a taxonomy of the various procedural irregularities that were found to have occurred, the responsibility of institutional actors for their occurrence, and their legal consequences. The final substantive sections of this article examine how the IOTC ultimately dealt with the situation and what potential role the available dispute settlement procedures could have had in addressing the discussed procedural irregularities. [ABSTRACT FROM AUTHOR]

Aquaculture is the fastest growing primary industry worldwide. Marine finfish culture in open ocean net pens, or pontoons, is one of the largest growth areas and is currently the only way to rear high value fish such as bluefin tuna. Ranching involves catching wild juveniles, stocking in floating net pens and fattening for 4 to 8 months. Tuna experience several parasite-induced disease challenges in culture that can be mitigated by application of praziquantel (PZQ) as a therapeutic. In this study, we characterized the microbiome of ranched southern Bluefin Tuna, Thunnus maccoyii, across four anatomic sites (gill, skin, digesta, and anterior kidney) and evaluated environmental and pathological factors that influence microbiome composition, including the impact of PZQ treatment on microbiome stability. Southern bluefin tuna gill, skin, and digesta microbiome communities are unique and potentially influenced by husbandry practices, location of pontoon growout pens, and treatment with the antiparasitic PZQ. There was no significant relationship between the fish mucosal microbiome and incidence or abundance of adult blood fluke in the heart or fluke egg density in the gill. An enhanced understanding of microbiome diversity and function in high-value farmed fish species such as bluefin tuna is needed to optimize fish health and improve aquaculture yield. Comparison of the bluefin tuna microbiome to other fish species, including Seriola lalandi (yellowtail kingfish), a common farmed species from Australia, and Scomber japonicus (Pacific mackerel), a wild caught Scombrid relative of tuna, showed the two Scombrids had more similar microbial communities compared to other families. The finding that mucosal microbial communities are more similar in phylogenetically related fish species exposes an opportunity to develop mackerel as a model for tuna microbiome and parasite research.

Tunas are among the most economically important fish species and play critical roles in food composition and nutrition of humans. As apex predators, they also keep the marine ecosystem healthy and balanced. Both natural and human factors influence the status of this important marine resource and their habitats. There is a large cadre of studies on how tunas are of great significance to the exploitation and management of their fisheries, yet there are few summaries of this research. We aimed to quantitatively and qualitatively synthesize the global knowledge structure and emerging trends in tuna research using bibliometric software. References with ''Tuna'', ''Katsuwonus'', or ''Thunnus'' as the subject in the Web of Science Core Collection Database from 1995 to 2019 were visually analyzed using CiteSpace. Publication rate and output, active countries, institutions, authors, and co-cited references were performed. Results suggested that the number of international tuna research papers increased significantly between 2000 and 2010, as a considerable number of high-impact articles emerged during this period. Researchers paid more attention to 19 main topics during this period, notably ''overfishing'', ''bycatch'', ''climate change'', ''marine pollution'', and ''fish management'', which all posed potential risks and challenges to tuna survival. Future research should emphasize resolving these challenges and building international cooperation for the proper management of tuna populations.

Despite the ubiquity of ultrasonography in nondestructive inspection, its application to high-attenuation materials is challenging. At frequencies less than 1 MHz, ultrasound can inspect high-attenuation materials owing to its high penetration ability. Such ultrasound data are acquired using a single-element transducer that generates single-channel signals (A-mode). However, low-frequency A-mode ultrasound signals have low-resolution caused by long wavelengths, and less information than B-mode images generated by multi-channel transducers. Discriminating low-resolution data is made possible by recent advances in machine learning technology. This study employs machine learning to develop an inspection method for high-attenuation frozen materials. This study focuses on the inspection of the freshness of frozen tuna, which has a large market but uses a destructive inspection method. We applied eight typical machine learning algorithms to A-mode signal data (43 samples, 3168 signals) of frozen tuna to calculate freshness scores; we used fast Fourier transform in the feature extraction process. Our experiments show that all algorithms could classify the freshness of frozen tuna with statistical significance ( ${p}$ < 0.05, one-tailed ${t}$ -test). Furthermore, we investigated the performance improvement in the mean (standard deviation) of the area under the receiver operating characteristic curves by taking the mean of the freshness scores on 24 signals. We observed that the best performance (quadratic discriminant analysis) increased from 0.619 (0.041) using a single signal to 0.724 (0.080) using 24 signals with statistical significance ( ${p}$ < 0.05, paired one-tailed ${t}$ -test). This is the first study that inspects frozen tuna using ultrasound and machine learning technology.

The coast of Sadeng Beach is a large potential for marine and fishery resources, which is, one of the potentials is tuna fish commodities. However, the utilization of these resources is still not optimal. The limited use of technology has hampered the processing and marketing of the products, resulting in a decrease in the economic value of tuna products. This Program Kemitraan Masyarakat (PKM) activity aims to boost community development by empowering the processing of marine fish products. So that, they become products that are worth selling higher. Empowerment carried out includes the provision of materials, equipment, and training in the manufacture of processed tuna products aimed at self-reliance and community self-reliance. The training covers how to process tuna raw materials from start to finish which includes raw material preparation, storage, additional seasoning, packaging, and distribution. The activity was carried out in Pucung Village, Girisubo District, Gunungkidul Regency by involving members of the Usaha Peningkatan Pendapatan Keluarga Sejahtera (UPPKS) Harapan. The method used in this activity is the Participatory Rural Appraisal (PRA) method which involves active community participation and empowerment. Activities include providing materials and practices for processing tuna fish into tuna cracker products, tuna nuggets, and tuna tofu. The program impacts increasing knowledge and skills of tuna fish processing for empowering partners. Through this activity, the women of the UPPKS Harapan group can contribute economically to the household. The training activities were held on June 11 2022 for the assistance stage for the introduction of tuna processing materials, June 12-October 2022 for product marketing assistance, November 2 2022 assistance for creating social media content until the final evaluation stage is ongoing.

Abstract Archival (data-storage) and telemetry (acoustic and radio) tags are commonly used to provide data on the behavior and physiology of organisms, as well as data on their surrounding environment. For fishes, it is often advantageous to implant tags in the peritoneal cavity (i.e., intracoelomic implantation). The literature on best practices is limited for marine species, and near absent for tunas despite their regular application. We identify recommended practices using laparotomy in tropical tuna species following observations from thousands of tags implantations undertaken during implementation of several tagging programs across the Pacific. These recommended practices include descriptions of preferred tagging stations and equipment, fish selection, surgical procedures, and return of the fish to the wild. While these recommended practices were developed specifically for tropical tuna species, they are also likely applicable for other pelagic fishes. We present these guidelines to guide and promote the development of best practices for such procedures on pelagic species.

The Neolithisation process altered human dependence on wild food sources, and dominant models of the Neolithic transition in Scandinavia still focus on cultural divisions. This study emphasises the evidence of creolization processes, in particular the exploitation of Atlantic Bluefin tuna (Thunnus thynnus) among Neolithic fisher-farmers north and east of the Skagerrak Sea in Scandinavia (4000–2350 cal BCE). The site Jortveit in Southern Norway, where Bluefin tuna was caught with toggling harpoons, is used as a point of departure. In order to understand this phenomenon, the first empirical review of prehistoric toggling harpoons in Central and Eastern Europe is presented. Toggling harpoons first appeared in the late Vinĉa Culture, then in the Gumelniţa, Cucuteni-Trypillia, and Sredny Stog cultural complexes further east, and finally in Central Europe and Scandinavia during the time of the Funnel Beaker Culture. Considering the accumulated evidence of long distance contact from Eastern to Central Europe and Scandinavia in the early fourth millennium BCE, it is argued that toggling harpoon technology was distributed through trade networks. Its appearance around the Skagerrak Sea in the Neolithic reflects fisher-farmers using a creolized fishing technology, inspired by Eneolithic societies.

Tuna and tuna-related fish are valuable marine species lacking standardized quality assessment parameters. This study assessed the physico-chemical and sensory properties of skipjack (Katsuwonus pelamis), bigeye (Thunnus obesus), yellowfin (Thunnus albacares), and kawakawa (Euthynnus affinis) tuna fish fillets marketed in Tanga and Mtwara, Tanzania. Laboratory AOAC methods evaluated total volatile basic-nitrogen (TVB-N), pH, color (lightness L*), and texture (hardness) properties. The quality index method (QIM) assessed tuna fillets’ sensory properties (color, texture, and odor). The pH ranged between 5.60 ± 0.08 and 6.10 ± 0.30, the TVB-N between 34 ± 7.00 mg/100 g and 38.04 ± 10.50 mg/100 g, color lightness (L*) between 24.33 ± 1.82 and 40.10 ± 1.50, and texture (hardness) from 3.84 ± 1.20 N to 8.56 ± 1.84 N. The tuna fillets got an overall score of 2 in the sensory analysis, which indicated good quality according to the QIM. Furthermore, the present study showed significant differences (p .05) in average TVB-N results across all tuna fillets. There were significant correlations among the assessed quality properties. Based on the combined quality properties results and correlation analysis, the tuna and tuna-related fish marketed in the study areas were of good quality. This study recommends the establishment of standardized quality assessment parameters for tuna and related fish species.

The objective of this work was to study the application of high-pressure processing (HPP) on the quality change and extending the shelf-life of yellowfin tuna (Thunnus albacares) stored at low temperature. The effects of HPP treatments (200, 300, 400, 500, and 600 MPa for 5 min) on microbiological and chemical quality, and histamine content of tuna flesh stored at 4°C and 15°C, respectively, were evaluated. With the increased pressure, the levels of aerobic plate count (APC) and coliform in tuna flesh significantly decreased. It was also found that the L* (lightness), b* (yellowness), W (whiteness), ΔE (color difference), and texture (hardness, cohesiveness and chewiness) of fish flesh increased significantly with the increased pressure; however, a* (redness) value decreased. Furthermore, HPP with a pressure of >300 MPa on tuna samples significantly delayed the increase in APC during storage at 4°C or 15°C, respectively, while the samples pressurized more than 200 MPa had significantly lower levels of total volatile basic nitrogen (TVBN) and histamine compared to the control samples during storage. The results indicated that tuna flesh pressurized at least 300 MPa for 5 min could be a technique employed to extend the shelf-life to 1 d at 15°C and 6 d at 4°C, based on the APC limit standard (6.47 log CFU/g). In this study, HPP can be seen as a potential useful technique to preserve tuna flesh due to its ability to reduce bacterial load and retard TVBN and histamine production.

Seven different methods of DNA extraction were performed and compared in order to have the better DNA recovery in terms of quality and quantity. A PCR assay was realised based on the Cytb mitochondrial gene to identify 53 commercial food products of wide range diversity (Scombridae Thunnus species) commercialised in the Tunisian market, and we checked whether these products were correctly labelled under European and national legislations. Phylogenetic analyses on Cytb mitochondrial gene were used to study the relationships among the considered species. Tuna species was easily differentiated and confirmed by direct sequencing. The results showed a high deficiency in labelling: 96% of canned tuna did not specify the species, although the name of the species had to be mentioned. Partial least squares regression (PLS) showed relatively high values (45%) in all analysed data, suggesting substantial difference between the extraction procedures and matrices with SDS/PCI method being the most convenient.

Background: Fish is a food ingredient that is consumed throughout the world. When fishes die, their freshness begins to decrease. The freshness of the fish can be determined by the aroma it produces. The purpose of this study is to monitor the odor of fish using a collection of gas sensors that can detect distinct odors. Methods: The sensor was tested with three kinds of samples, namely Pseudomonas aeruginosa, tuna, and tuna that was contaminated with P. aeruginosa bacteria. During the process of collecting sensor data, all samples were placed in a vacuum so that the gas or aroma produced was not contaminated with other aromas. Eight sensors were used which were designed and implemented in an electronic nose (E-nose) device that can withstand aroma. The data collection process was carried out for 48 h, with an interval of 6 h for each data collection. Data processing was performed by using the principal component analysis and support vector machine (SVM) methods to obtain a plot score visualization and classification and to determine the aroma pattern of the fish. Results: The results of this study indicate that the E-nose system is able to smell fish based on the hour with 95% of the cumulative variance of the main component in the classification test between fresh tuna and tuna fish contaminated with P. aeruginosa. Conclusion: The SVM classifier was able to classify the healthy and unhealthy fish with an accuracy of 99%. The sensors that provided the highest response are the TGS 825 and TGS 826 sensors.

To scientifically evaluate the nutritional components and flavor substances of different muscle parts of bigeye tuna, yellowfin tuna and bluefin tuna, the differences among different species and parts of three tuna species were compared through basic nutrients, amino acid composition, fatty acid composition and volatile flavor substances, which detected using national standard method and gas chromatography-ion migration spectrometer. The results showed that moisture content of three tuna species was quite different. The moisture content of different muscle parts was varied from 50.16 to 79.37 g/100 g, while the moisture content of bluefin tuna was significantly lower than the other two tuna species (P

Inadequate calcium intake during childhood and adolescence is detrimental to bone metabolism. Here, we postulated that calcium supplement prepared from tuna bone with tuna head oil should benefit for skeletal development than CaCO3. Forty female 4-week-old rats were divided into calcium-replete diet (0.55% w/w, S1, n = 8) and low-calcium groups (0.15% w/w for 2 weeks; L; n = 32). Then L were subdivided into 4 groups (8/group), i.e., remained on L, L + tuna bone (S2), S2 + tuna head oil + 25(OH)D3 and S2 + 25(OH)D3. Bone specimens were collected at week 9. We found that 2 weeks on low calcium diet led to low bone mineral density (BMD), reduced mineral content, and impaired mechanical properties in young growing rats. Intestinal fractional calcium absorption also increased, presumably resulting from higher plasma 1,25(OH)2D3 (1.712 ± 0.158 in L vs. 1.214 ± 0.105 nM in S1, P < 0.05). Four-week calcium supplementation from tuna bone further increased calcium absorption efficacy, which later returned to the basal level by week 9. Calcium supplementation successfully restored BMD, bone strength and microstructure. However, 25(OH)D3 + tuna head oil + tuna bone showed no additive effect. Voluntary running also effectively prevented bone defects. In conclusion, both tuna bone calcium supplementation and exercise are effective interventions for mitigating calcium-deficient bone loss. [ABSTRACT FROM AUTHOR]

The shape of sagitta otoliths was used to compare individuals of little tunny (Euthynnus alleteratus) harvested on board commercial fishing vessels from the coastal areas along the Eastern Atlantic, including the Mediterranean Sea. Fish sampling and selection was designed to cover possible seasonal changes and tuna size. The research encompassed both morphometric and shape analyses of left sagittal otoliths extracted of 504 fish specimens. Four shape indices (Circularity, Roundness, Rectangularity, and Form-Factor) were significantly different between two groups, showing a statistical differentiation between two clear spatial units. The degree of divergence was even more pronounced along the rostrum, postrostrum, and excisura of the generated otolith outlines between these two groups. One group corresponds to the samples from the coastal areas in the Northeast Temperate Atlantic and Mediterranean Sea (NETAM Area) and a second group from the coastal areas off the Eastern Tropical Atlantic coast of Africa (ETA Area). This study is the first to use otolith shape to differentiate tunas from separate spatial units. These results could be used to re-classify previously collected samples and to correct time series of data collected. [ABSTRACT FROM AUTHOR]

The genus Thunnus (family Scombridae) comprises eight species of tunas of which all but one are targeted by industrialized fisheries. Although intact individuals of these species can be distinguished by morphological characteristics, researchers and managers often rely on dressed, frozen, juvenile or larval fish samples, which often necessitates the identification of molecular species. Here the authors investigate short amplicon (SA) and unlabelled probe high‐resolution melting analysis (UP‐HRMA) as a low‐cost, high‐throughput molecular genotyping assay capable of distinguishing between albacore tuna (Thunnus alalunga), blackfin tuna (Thunnus atlanticus), bigeye tuna (Thunnus obesus), Atlantic bluefin tuna (Thunnus thynnus) and yellowfin tuna (Thunnus albacares) in the Gulf of Mexico. Although SA‐HRMA of variable regions in the NADH dehydrogenase subunit 4 (ND4) and subunit 5 (ND5), and subunit 6 (ND6) of the mtDNA genome did yield some species‐specific diagnostic melting curves (e.g., ND4 assay can reliably distinguish Atlantic bluefin tuna), genotype masking produced excessive variation in melting curves for reliable multi‐species identification. To minimize the genotyping masking of SA‐HRMA a 26 base pair long UP containing four SNPs was developed within a 133 bp segment of ND4. The UP‐HRMA is able to reliably distinguish Gulf of Mexico species T. thynnus, T. obesus, T. albacares and T. atlanticus by UP melting temperature at 67, 62, 59 and 57°C, respectively. The developed UP‐HRMA assay is a lower‐cost, higher‐throughput, alternative to previously published molecular assays for tuna identification that can be easily automated for large data sets, including ichthyological larval surveys, fisheries specimens lacking distinguishing morphological characteristics or detection of fraudulent trading of tuna species. [ABSTRACT FROM AUTHOR]

Morphological evolution of the vertebrate skull has been explored across a wide range of tetrapod clades using geometric morphometrics, but the application of these methods to teleost fishes, accounting for roughly half of all vertebrate species, has been limited. Here we present the results of a study investigating 3D morphological evolution of the neurocranium across 114 species of Pelagiaria, a diverse clade of open-ocean teleost fishes that includes tuna and mackerel. Despite showing high shape disparity overall, taxa from all families fall into three distinct morphological clusters. Convergence in shape within clusters is high, and phylogenetic signal in shape data is significant but low. Neurocranium shape is significantly correlated with body elongation and significantly but weakly correlated with size. Diet and habitat depth are weakly correlated with shape, and nonsignificant after accounting for phylogeny. Evolutionary integration in the neurocranium is high, suggesting that convergence in skull shape and the evolution of extreme morphologies are associated with the correlated evolution of neurocranial elements. These results suggest that shape evolution in the pelagiarian neurocranium reflects the extremes in elongation found in body shape but is constrained along relatively few axes of variation, resulting in repeated evolution toward a restricted range of morphologies. [ABSTRACT FROM AUTHOR]

Manta rays and tunas are outstanding representatives of propulsion by MPF (median and/or paired fin) and BCF (body and/or caudal fin), respectively, and it is an interesting topic to see what kind of fluid effects will be generated when they meet during the swimming process. In the present study, numerical simulations were performed for the individual swimming state of manta ray/tuna and the group swimming of manta ray and tuna in a tandem arrangement. In individual swimming conditions, increasing amplitude helps to improve manta ray thrust and increasing wave number helps to improve manta ray efficiency; increasing frequency, tuna thrust increases monotonically and efficiency increases first and then decreases. In the tandem group swimming state, the manta ray thrust and efficiency are enhanced at most spacings, the smaller the spacing, the greater the enhancement, as seen in the vortex structure, which benefits from the merging of the rear tuna wake. The thrust and efficiency curves of the tuna fluctuate greatly with spacing, which is related to the position of the manta ray wake field where the tuna are located. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the nutritional quality and concentration of heavy and toxic metals in the fresh and canned tuna Thunnus tonggol at different storage periods. The content of iron, zinc, copper, mercury, and also macronutrient compounds in the Iranian fresh and canned tuna fish and the effects of thermal processing and subsequent storage on metal contents were evaluated using atomic absorption spectroscopy. The results showed that the levels of iron, zinc, copper, and mercury after the 6th, 9th, and 11th months of storage were 26.52, 10.83, 6.22, and 0.04 mg/kg, respectively. The concentrations of iron, zinc, copper, and mercury in the fresh fish were 11.03, 7.11, 1.71, and 0.03 mg/kg, respectively. The results of the statistical analysis of the samples showed that canning process and sterilization by autoclave increased the contents of elements except mercury to a significant level (p <.05). The results showed that the amount of fat significantly increased in all samples after storage (p <.05), but the ash and protein content significantly decreased (p <.05). The moisture content significantly increased (p <.05) except for the 9th month of storage. The obtained results showed that the energy value after 6 months of storage was the highest (297.53 kcal/100 g). The results showed that the bioaccumulation of copper, iron, zinc, and mercury in the fresh and canned muscles was lower than the standard concentration recommended by the FAO and WHO. This type of fish was a high‐quality food source and it was safe after 11 months of storage and was suitable for human consumption. Therefore, the consumption of Iranian canned tuna can be safe for human health despite the possible contamination with heavy metals. [ABSTRACT FROM AUTHOR]

Interest in retail seafood sales increased dramatically with the onset of the COVID‐19 pandemic. The diversity of species, types of products, product forms, and packaging of the seafood sold at retail, combined with diverse consumer preferences across the United States, requires detailed data and analysis to provide guidance and understanding of emerging trends. Weekly, store‐based, Nielsen Scantrack data for the period of September 2016 through August 2021 were used to compare trends in US retail (supermarket) seafood sales across the 5‐year study period, in continental regions, cities, and species categories sold. Results showed continuous increases in retail seafood sales over the study period at an average annual growth rate of 8.1%, much of which was fueled by the 21% increase in total sales (19.5% increase in quantity sold) the first year after the onset of the pandemic. The South Atlantic region was found to have the greatest total sales and sales per capita among regions. New York City had the greatest total seafood sales, followed by Los Angeles and Philadelphia. The top five most important species categories in terms of sales were, in declining order, shrimp, salmon, tuna, crab, and tilapia, although regional variability became apparent from the fourth‐ranked species. The most important package sizes were 454‐ and 907‐g packs. Frozen and refrigerated categories dominated sales (70% in 2021), with little growth in entrées and a decline in market share of shelf‐stable seafood products in 2021. Retail supermarket seafood sales increased dramatically following the onset of the pandemic, with especially notable percentage increases in lobster (77%) and crab sales (70%) and the lowest percentage increases in tuna (1%) and tilapia (13%). Given that US per capita seafood consumption did not show a corresponding increase over the study period, study results likely indicate a shift to greater relative consumption at home and not an overall increase in US seafood sales. [ABSTRACT FROM AUTHOR]

Catch-and-effort data are among the primary sources of information for assessing the status of terrestrial wildlife and fish. In fishery science, elaborate stock-assessment models are fitted to such data in order to estimate fish-population sizes and guide management decisions. Given the importance of catch-and-effort data, we scoured a comprehensive dataset pertaining to albacore tuna (Thunnus alalunga) in the north Pacific Ocean for novel ecological information content about this commercially valuable species. Specifically, we used unsupervised learning based on finite mixture modelling to reveal that the north Pacific albacore-tuna stock can be divided into four pseudo-cohorts. We discovered that smaller body mass pseudo-cohorts inhabit relatively high—subtropical to temperate—latitudes, with hotspots off the coast of Japan. Larger body mass pseudo-cohorts inhabit lower—tropical to subtropical—latitudes, with hotspots in the western and central north Pacific. These results offer evidence that albacore tuna prefer different habitats depending on their body mass, and point to long-term migratory routes for the species that the current tagging technology is unlikely to capture in full. We discuss the implications of the results for data-driven modelling of albacore tuna in the north Pacific, as well as the management of the north Pacific albacore-tuna fishery. [ABSTRACT FROM AUTHOR]

Dry-cured tuna is a traditional product manufactured in the Mediterranean region of Spain, known as mojama. The traditional salting-drying elaboration process attributes new organoleptic characteristics to the final product, changing its flavor, color, and nutritional value. This study aimed to evaluate the changes in physicochemical, biochemical, and microbiological parameters taking place during the process. The physicochemical parameters were affected by the processing steps (salting, salt-washing, and drying), except for total acidity and pH. The water activity value and relative moisture percentage decreased to 0.86 and 33.03%, respectively. Moreover, the addition of salt and the drying step increased the water-holding capacity. The lipid oxidation values increased from raw tuna loins to the final product (1.37 vs. 5.56 mg malondialdehyde/kg). Moreover, the total volatile basic nitrogen values increased in the final product, fundamentally due to the concentration effect caused by the water loss, although may also be due to the degradation of proteins during processing. The microbiological analysis showed that the values obtained in the dry-cured tuna were below the limits established by the reference regulation for dry-cured fish products. [ABSTRACT FROM AUTHOR]

Sample cross-contamination remains a pervasive issue in genetics and genomics. With growing reliance on molecular methods for managing marine resources, the need to ensure the integrity of tissue samples that underpin these methods has never been more pressing. We conducted an experiment on wild-caught bigeye tuna (Thunnus obesus) to assess cross-contamination risk under seven at-sea and laboratory-based tissue sampling treatments. The six at-sea treatments (T1–T6) differ in sampling equipment, cleaning, and storage procedures. Combining observed heterozygosity (H o) and relatedness coefficients (r) to flag cross-contamination, treatments T2–T6 proved effective at mitigating contamination risk. Each exhibited significantly smaller mean H o and less H o variability compared with intentionally contaminated samples in the T1 treatment. In T2-T6, no samples flagged as contaminated based on H o outlier thresholds and elevated r were traced to the point of sampling at sea. Laboratory-based subsampling of T1 tissue (T7) also led to significantly smaller, less variable H o values compared to T1, suggesting that recovery of samples contaminated onboard, or those of unknown provenance, is possible. We show that simple adjustments to current tissue sampling protocols dramatically reduce cross-contamination risk for downstream genetic analyses on tunas and potentially on other species and fisheries. [ABSTRACT FROM AUTHOR]

Blackfin tuna (Thunnus atlanticus) is a small tuna distributed in the western Atlantic Ocean where it is exploited by growing recreational and commercial regional fisheries. In this work, genome-wide genetic variation was analysed to investigate the occurrence of stock subdivision. A de novo assembly of the blackfin tuna genome was generated using Illumina paired-end sequencing data and applied as a reference for population genomic analysis of specimens from nine localities (average sample size per locality n  = 72) spanning most of the blackfin tuna distribution range. A total of 2139 single-nucleotide polymorphisms were discovered and genotyped using the double-digest restriction associated DNA sequencing. Pairwise exact homogeneity tests were significant in 24 out of 36 population pairs and significant spatial autocorrelation of genotypes was observed for specimens collected within 2250 km of each other. However, divergence among locality samples was very low (pairwise F ST range 0.0002–0.0025) and significant temporal variations were detected in localities sampled multiple times. Approaches to detect cryptic groups de novo were unsuccessful. Additional sampling is warranted to determine if multiple stocks need to be defined for management and assess temporal and spatial patterns of gene flow connecting them. [ABSTRACT FROM AUTHOR]

Tuna fisheries provide over 5 million tonnes of seafood annually to the global market but have historically raised conservation concerns due to weak management measures and impacts on non‐target wildlife. The focus of the first environmental awareness campaigns in seafood focused on dolphin bycatch in tuna fisheries in the 1980s. Since then, the sustainable seafood movement has evolved considerably, with philanthropic foundations playing a key role as agenda‐setters and funders of work carried out by non‐governmental organizations (NGOs). Here, we used tuna as a case study and investigated how three US foundations and associated NGOs have affected tuna fisheries reform through two primary pathways: advocacy for improved fishery management at intergovernmental meetings, and engagement with fishing companies in fishery improvement projects (FIPs). We found a total of USD 28.65 million was allocated to tuna‐related work from 2013 to 2021. While each foundation had different funding profiles, 65% of all grant funds were directed to two key priority areas: market leverage and RFMO advocacy. Further, almost 60% of all funding was allocated to only three NGOs, all of which are central actors at RFMO meetings, and which are collectively engaged in over 85% of all tuna FIPs (by volume). We reflect on how this concentrated funding relates to the overarching sustainable seafood agenda of these foundations and provide recommendations to ensure financial support and objectives remain transparent and do not perpetuate inequities between tuna fishing countries. [ABSTRACT FROM AUTHOR]

A specimen of bull ray Aetomylaeus bovinus was captured dead by a diver around a tuna sea cage farm. It was female, measured 2310 mm in total length (TL) and 1460 mm in disc width (DW) with body weight estimated as about 20 kg. This case was reported from a tuna farm for the first time. The bull ray entered the sea cage about three months ago, but no attack occurred to the tuna in the cage. It was grazing on fouling organisms that attached to the nets. However, the cage nets were replaced with clean ones four days ago before the capture, and the bull ray did not find enough fouling organisms or uneaten fish feed and was starved to death. [ABSTRACT FROM AUTHOR]

To achieve high-precision forecasting of different grades of albacore fishing grounds in the South Pacific Ocean, we used albacore fishing data and marine environmental factors data from 2009 to 2019 as data sources. An ensemble learning model (ELM) for albacore fishing grounds forecasting was constructed based on six machine learning algorithms. The overall accuracy (ACC), fishing ground forecast precision (P) and recall (R) were used as model accuracy evaluation metrics, to compare and analyze the accuracy of different machine learning algorithms for fishing grounds forecasting. We also explored the forecasting capability of the ELM for different grades of fishing grounds. A quantitative evaluation of the effects of different marine environmental factors on the forecast accuracy of albacore tuna fisheries was conducted. The results of this study showed the following: (1) The ELM achieved high accuracy forecasts of albacore fishing grounds (ACC = 86.92%), with an overall improvement of 4.39~19.48% over the machine learning models. (2) A better forecast accuracy (R2 of 81.82–98%) for high-yield albacore fishing grounds and a poorer forecast accuracy (R1 of 47.37–96.15%) for low-yield fishing grounds were obtained for different months based on the ELM; the high-yield fishing grounds were distributed in the sea south of 10° S. (3) A feature importance analysis based on RF found that latitude (Lat) had the greatest influence on the forecast accuracy of albacore tuna fishing grounds of different grades from February to December (0.377), and Chl-a had the greatest influence on the forecast accuracy of albacore tuna fishing grounds of different grades in January (0.295), while longitude (Lon) had the smallest effect on the forecast of different grades of fishing grounds (0.037). [ABSTRACT FROM AUTHOR]

Tuna is one of the most popular fish and therefore among the most commercially valuable seafood. However, inadequate refrigeration during the whole supply chain causes serious economic loss and food poisoning. One important result of tuna spoilage is the accumulation of biogenic amines such as histamine, which can be used as a sensitive indicator for Tuna freshness. Thus, the development of rapid, sensitive, and economic analytical methods for biogenic amines in Tuna is highly desired. This research developed a method that combines high-performance liquid chromatography (HPLC) and electrospray ionization ion mobility spectrometry (ESI-IMS) to detect 7 kinds of biogenic amines including tryptamine, tyramine, spermidine, cadaverine, β-phenylethylamine, putrescine, and histamine in tuna. The limit of detections (LODs) for 7 biogenic amines are 0.01, 0.02, 0.02, 0.17, 0.03, 0.04, and 0.15 mg L−1 respectively. The linear range of histamine and spermidine is 2–100 mg kg−1, and the linear range of other biogenic amines is 0.5–10 mg L−1. The recoveries of biogenic amines are between 69.39 and 112.65%. Compared to the traditional HPLC-based analytical method, the proposed method does not involve any derivatization steps, which greatly decreased the sample preparation time and cost. Another advantage of the developed method is the supplementary separation to the HPLC, in which coeluted biogenic amines can clearly be separated in the ion mobility dimension. The proposed method is applied to determining the concentration of biogenic amines in tuna storage, which showed that this method can quickly and accurately monitor the changes of biogenic amines in tuna during storage. [ABSTRACT FROM AUTHOR]

Bigeye tuna (Thunnus obesus) is economically vital in the Indian Ocean, targeted extensively for commercial fishing. Research using a blend of quantitative and qualitative Indian Ocean Tuna Commission (IOTC) data from 1950 to 2021 uncovered insights. Around 35 countries participated in Indian Ocean bigeye tuna fishing, annually yielding 21 to 162,220 t over the study period. Yet, since 1999, catches dwindled, dipping below 100,000 t from 2014 to 2021. The highest quantity of bigeye tuna captured in the Indian Ocean during this period was by longliners under the flag of Taiwan, Province of China, accounting for 24.08% of the total catch. Thailand's catch, by contrast, accounted for 14,676 t (0.30%) and came from purse seines and longlines. The Western Indian Ocean was the primary fishing ground for bigeye tuna, followed by the Eastern Indian Ocean. However, the stock of bigeye tuna is currently overfished and subject to overfishing, with 2021 catches amounting to 95,400 t, representing a 5% increase from 2020. To address this issue, an allocation based on the catch during 2012-2016 was recommended for Contracting Parties and Cooperating Non-Contracting Parties. A conceptual model has been created to ensure bigeye tuna sustainability through four processes: apply management regulations, recommend total allocation catch (TAC) for 2024-2025, control actual catch, and revisit/readjust TAC if needed. The model promotes long-term sustainability. To ensure compliance with IOTC Conservation and Management Measures for bigeye tuna, Thailand must align national law with the IOTC Resolution, notably Royal Ordinance on Fisheries B.E. 2558 (2015) and its B.E. 2560 (2017) amendment. This legal synchronization is crucial, especially for quota transfers and chartering. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate and compare between some local and imported canned tuna products sold in supermarkets of Kafr El Sheikh Governorate, through physicochemical, bacteriological and sensory parameters assessment also, determining mercury and histamine level to ensure product safety. The results revealed that all examined tuna samples physiochemical parameters (pH, total volatile nitrogen (TVN), and thiobarbituric acid (TBA)) were compatible with the Egyptian specifications and considered safe for consumption. The microbial examinations indicated that samples show incidence of S. aureus was 44% for imported tuna. While for local chunk and shredded were 56% and 67%, respectively. In addition to detection of its enterotoxins, which were 11% and 22% for local chunk and shredded samples, respectively. The enterotoxins of isolated S. aureus were type A, detected from local chunk and types A, C, and D from local shredded samples. The incidence of anaerobic bacteria was 22% and 33% for local chunk and shredded samples, respectively, but not detected in imported samples with no detection of Clostridium perfringens in all local and imported samples. However, the imported and local samples were significantly different. All local tuna samples contained high level of mercury exceeded the permissible limits of 0.5 mg/kg while, the imported samples within the limit. Also, histamine levels were found within the Egyptian Standards of (20 mg/100 g) although there was a significant difference between imported and local samples. In conclusion, the results pointed out that all examined local and imported canned tuna samples agreed with the Egyptian and other standards making them considered safe for human consumption. [ABSTRACT FROM AUTHOR]

Tuna are economically important fish species. The automated identification of tuna species is of importance in fishery production and resource assessment in that it would facilitate the informed monitoring of tuna fishing vessels and the establishment of electronic observer systems. As morphological characteristics are important for tuna identification, this study aims to verify the performance of the automated identification of three Thunnus species through morphological characteristics based on different machine learning algorithms. Firstly, morphological outlines were visually analyzed using EFT (elliptic Fourier transform) and CNN (convolutional neural network). Then, the EFT feature data and deep feature data of the tuna outline images were extracted, and principal component analysis of the two different morphological characteristics was performed. Finally, different machine learning algorithms were used to analyze the identification performance of tuna of the same genus and different species. The experimental results showed that EFT features had the highest identification accuracy in KNN (K-nearest neighbor), with 90% for T. obesus, 90% for T. albacores, and 85% for T. alalunga. Deep features had the best identification performance in SVM (support vector machine), with 80% for T. obesus, 90% for T. albacores, and 100% for T. alalunga. Deep features were better than EFT features in identification performance. The biodiversity and intergeneric differences among tuna species can be well analyzed using these two different morphological characteristics. Machine learning algorithms open up the way for rapid near-real-time electronic observer systems in these important international fisheries. [ABSTRACT FROM AUTHOR]

Fisheries extension programmes frequently fail to secure mandatory or voluntary adoption of bycatch reduction devices and techniques. Approaches for improving the outcomes of extension programmes are often based on ad hoc assessments and do not consider human behaviour or change theories. This paper offers an in-depth analysis of extension activities that led to various adoption outcomes in two prominent bycatch case studies in the United States: turtle excluder devices in shrimp trawl fisheries and dolphin bycatch in the tuna purse seine fishery. Using a grounded theory approach to text analysis of interviews and documents, I examine five periods of voluntary or mandatory adoption efforts. I explain the outcomes through the lens of diffusion of innovation theory. The most effective extension programme involved informative and persuasive efforts, enforced regulations, and commercially practical bycatch reduction devices. Voluntary adoption occurred under exceptional circumstances of public and political pressure and a device that offered substantial benefits to the adopter. The two periods of successful adoption applied the most core principles of diffusion theory. This paper concludes with recommendations for how change agents can apply diffusion theory to future fisheries extension programmes to improve the adoption of bycatch reduction devices. [ABSTRACT FROM AUTHOR]

Background and Aim: Yellowfin tuna and swordfish are seafood commodities commonly caught from deep oceans worldwide. Therefore, this study aimed to assess the levels of three heavy metals, namely, cadmium (Cd), lead (Pb), and mercury (Hg) in yellowfin tuna and swordfish. The results are expected to provide consumers with information on the safety of consuming or exporting these fishes caught in the Hindian and Pacific Oceans. Materials and Methods: Fresh yellowfin and swordfish were obtained from fishermen's catches in FAO Fishing Zone 57 (Indian Ocean) and 71 (Pacific Ocean) and then collected at Benoa Harbor, Bali Province. The comparative method was to evaluate the levels of heavy metals in each fish. Furthermore, heavy metal concentrations, including Pb, Cd, and Hg, were determined using atomic absorption spectroscopy analysis. These results were then used to assess the safety of these fishes by calculating the estimated daily intake (EDI) and target hazard quotients-total target hazard quotients (THQs-TTHQs). Results: The analysis showed that none of the samples exceeded the threshold levels for the three heavy metals, which was specified by the Indonesian National Standard (SNI) and European Commission Regulation (CR) No. 1881/2006. The EDI and provisional tolerable weekly index (PTWI) obtained in this study were still in the safe range. However, the PTWI values for Pb in yellowfin tuna product from the Indian Ocean were higher (0.0038 mg/kg) compared to the recommended standard for the adult population. The THQ-TTHQ values of fish caught from these oceans were also within the acceptable range specified by the two agencies, indicating that they are safe for consumption by people with various age groups and for export purposes. Conclusion: The average levels of three heavy metals (Cd, Pb, and Hg) in muscle samples of yellowfin tuna and swordfish caught from the Pacific and Hindian Oceans were within the acceptable range as specified by the SNI and CR No. 1881/2006. Furthermore, the EDI and THQs values indicated that fishes caught from the Pacific and Hindian Oceans were safe for consumption. This research is still limited to assessing two capture fisheries commodities. Further research is needed on the assessment of heavy metal levels in other capture fisheries commodities in this capture zone. [ABSTRACT FROM AUTHOR]

As a commercial fish, bullet tuna is constantly caught in purse seine fisheries to provide economic benefits for coastal communities. Biological information such as food preference has to be known due to their sustainability in the future. This research aims to figure out the food composition and preference of bullet tuna (Auxis rochei Risso, 1810) in Prigi Coast, Trenggalek Regency East Java. A total of 294 fish landed by purse seine fishermen have been collected from March up to May 2018. Each individual was measured in its total length and weight, then was dissected for sex determination, measured the length of intestine, and analyse the stomach content. The data analysis encompasses frequency distribution of total length, relative gut length, frequency of occurrence, index of preponderance, trophic level, niche breadth, and food overlapping. The research result indicates that the main foods of Auxis rochei are fish and crustacean, while the complementary and additional foods were copepod, mollusc, annelid, and debris. Bullet tuna was a carnivorous fish with the trophic level of 3.7 and shows the existence of competition for food resources. Overlapping of feeding occurred in the 19-20 cm long group against the 23-24 cm long group in male fish and the 19-20 cm size group against the 21-22 cm length group in female fish. Bullet tuna use the same feed resources among the size groups of fish, where females use feed over a wider area than males. [ABSTRACT FROM AUTHOR]

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Substantial global population declines in pelagic sharks have led to the introduction of management and conservation measures, including gear restrictions and no‐retention policies, to curb declines and encourage stock recovery. As the rate of discarding sharks increases, there is a growing need to understand prognostic factors that influence their post‐release survival (PRS) outcomes.PRS was measured with survival pop‐up satellite archival tags attached to shortfin mako (Isurus oxyrinchus) and silky sharks (Carcharhinus falciformis) released or discarded from pelagic tuna longline fishing vessels operating in the Western and Central Pacific Fisheries Commission Convention Area. In total, 117 tags were deployed on 60 mako and 57 silky sharks captured as bycatch during commercial pelagic longline fishing trips in New Zealand (n = 35), Fiji (n = 58), New Caledonia (n = 10) and the Republic of the Marshall Islands (n = 14).Mako engaged in long‐distance movements between New Zealand, Australia, Fiji and New Caledonia, while silky sharks tagged in the Marshall Islands showed evidence of seasonal movements eastward.PRS was determined for 110 sharks (57 mako, 53 silky sharks). Most tagged sharks of both species were uninjured (89%) at capture and most sharks (88%) survived post‐release until tag loss or the programmed pop‐up date (60 days). However, when considering a complete fishing interaction (haulback, handling, release), PRS estimates were markedly reduced to 48.6% and 52.3% for mako and silky sharks, respectively. For both species, survivorship was greater in large (>150 cm fork length) uninjured sharks and sharks released with low shark length to trailing branchline ratios.While these findings suggest that retention bans offer sharks an increased chance of survival, continued efforts should be made to improve handling and release practices, reduce trailing gear and minimize pelagic shark bycatch. [ABSTRACT FROM AUTHOR]

Bioaccumulation is the process by which living organisms accumulate substances, such as pesticides, heavy metals, and other pollutants, from their environment. These substances can accumulate in the organism's tissues over time, leading to potential health risks. Bioaccumulation can occur in both aquatic and terrestrial ecosystems, and can have a significant impact on the health of both humans and wildlife. The objective of this study is to find out if the concentrations of metals in the tuna species of the Canary Islands are suitable for human consumption and if they pose a health risk. Fifteen samples of Acanthocybium solandri, Katsuwonus pelamis, Thunnus albacares, Thunnus obesus and Thunnus thynnus present in canaries were analyzed. Ten grams of muscle were taken from each specimen and the metals Al, Cd, Cr, Cu, Fe, Li, Ni, Pb and Zn were determined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The tuna species that presented more metals with a higher concentration compared to the others was T. thynnus, reaching up to 100 times more than the other studied species in Fe content with 137.8 ± 100.9 mg/Kg, which may be due to the fact that it is the largest species that reaches ages of more than fifteen years. The species Thunnus thynnus should not be suitable for commercialization according to the current legislation on the concentrations of Cd in blue fish, since 75% of the specimens studied exceeded the concentration legislated for Cd. A total of 40% of the studied specimens of this this species exceeded the legislated values for the concentration of Pb in oily fish meat, so this species must be monitored to ensure that it does not pose a risk to human health. [ABSTRACT FROM AUTHOR]

This study aims to detect Clostridium botulinum and its control using natural leaf extracts of Citrus limon, Citrus sinensis, and Citrus unshiu in Egyptian fish products, e.g., canned tuna, canned sardine, canned mackerel, fesikh, moloha, and renga, as well the application of C. limon in tuna. Moreover, the antibacterial activity of the C. limon leaf extract was also estimated. In the water extract, ascorbic acid, total flavonoid content (TFC), and total phenolic content (TPC) were determined by volumetric, aluminum chloride, and Folin–Ciocalteu approaches, respectively. The antioxidant ability of the extract was analyzed in vitro via free radical scavenging (DPPH) and Ferric reducing assays. The results showed variability in the distribution of the total number of positive C. botulinum in fish samples from three different governorates under study, which were (24) Alexandria, (16) Beheira, and (17) Gharbia, out of the 120 tested samples in each governorate. Additionally, the findings revealed that all three Citrus extracts contain an appropriate number of secondary metabolites, with a sustainable presence of saponin and tannins in the C. limon extract. Furthermore, all Citrus extracts inhibited bacterial growth by increasing the inhibition zone, with C. limon being the best extract (25 mm) compared to C. sinensis and C. unshiu. The overall results showed the high antioxidant and anti-Clostridium powers (p < 0.05) of C. limon leaf extract, indicating its preservative activity in fishery products during storage. Finally, C. limon leaf extract can fight off C. botulinum and is considered a promising natural preservation candidate in ensuring safe and fresh fishery products. [ABSTRACT FROM AUTHOR]

Abstract The study's aim was to evaluate the microbiological, nutritional, textural quality and palatability of pet biscuits made with the inclusion of three flours. The treatments were chicken viscera flour (CVF), commercial Nile tilapia flour (FF) and mixed fish flours of several species (FVF). For the FVF, only the carcasses (backbones) of Nile tilapia, salmon, tuna and sardines were used, and they were washed, whereas FVF as well as the others were cooked for 60 minutes, then pressed, ground and dehydrated for 24 hours at 60° C. After this period, they were crushed and ground for inclusion in the biscuits. The CVF, FF and FVF flours showed 43.82%, 50.48% and 56.70% of crude protein, respectively. CVF had the highest lipid content (10.01%) and FVF had the highest ash content (23.94%) and FVF had the highest caloric value (338.63 kcal 100 g-1). The inclusion of flours in biscuits did not influence the protein and carbohydrate contents, whose average values were 18.48% and 50.23%. However, they influenced the moisture content, lipids, ash and caloric value. Biscuits with the inclusion of viscera (CVF) had the highest lipid content (5.91%) and those with fish had the highest ash content (5.66% and 5.81%) for FF and FVF. Biscuits with FVF had a lower caloric value (318.47 kcal 100 g-1). The microbiological analysis indicated that the biscuits were considered of good quality to feed dogs. Regarding texture and palatability, there was no significant difference between treatments. The inclusion of fish flour, both FF and FVF, is a viable alternative.

Though yellowfin tuna (Thunnus albacares) is one of the important fishery resources in the Bay of Bengal, knowledge on its ecology, diet composition and feeding habits are limited from this area. In view of that, present study focuses on the diet composition and feeding habits of yellowfin tuna (YFT) hooked during exploratory longline survey conducted in the Indian EEZ of the Bay of Bengal during 2019–2021. A total of 213 specimens in the length range of 42.0 to 171.0 cm fork length (FL) were examined, of which 28.2% were empty while the remaining 71.8% contained at least one prey item. The modified Costello graphical method shows a wide range of prey items, with a few prey species that are dominant and can be found in high densities in the Bay of Bengal. Due to the fact that this apex predator is a generalist feeder, this might be the case. Cluster analysis based on the %IRI (Index of relative importance) identified two size groups. YFT with smaller (120 FL), Cephalopods were the dominant prey items of this group and accounts for 62.0% in %IRI followed by teleostea 31.3% of the diet. Cephalopods (Sthenoteuthis oualaniensis) were the primary food consumed in all the size groups, followed by crustaceans (Charybdis smithii) and Teleost fishes (Cubiceps pauciradiatus). The dietary breadth and the occurrence of empty stomachs were significantly related to size of the yellowfin tuna. With increasing body size, diet breadth gradually increased while the percentage of empty stomachs declined. The yellowfin tuna diet does not vary significantly during the seasons. However, cephalopods were found in 53.5% of the IRI in their diet. Furthermore, there were notable seasonal changes in the percentage of empty stomachs, with the highest percentage observed during the monsoon season (38.3%).

This study addresses the effect of various cooking approaches on total Hg (HgT) and total Se (SeT) contents in three predatory fish species. For this purpose, samples of swordfish, dogfish, and tuna from regular French (fish) markets were cooked by boiling, steaming, grilling, and frying, respectively. The levels of HgT and SeT in raw and cooked samples were determined by inductively coupled plasma-mass spectrometry. The data showed a significant increase in HgT and SeT levels between raw and cooked samples (33% of the samples for SeT and 67% for HgT) due to the water loss during the cooking. High intra-species variation related to HgT and SeT levels was found. Considering the level of exposure to HgT through fish consumption and taking also into account the possible protective effect of Se (expressed here via the Se/Hg molar ratio), the safest cooking approach corresponds to grilled swordfish, fried tuna, and steamed dogfish, which show Se/Hg molar ratios of (1.0 ± 0.5), (4.3 ± 4.2), and (1.0 ± 0.6), respectively.

Today, world capture fisheries have reached their maximum capacity and the future of seafood supply is threatened by global environmental factors such as climate change, ocean pollution, acidification, and overfishing. Waste reduction, or a fuller utilization of every part of the wild caught fish, represents anopportunity to meet the increased demand in seafood consumption without further stressing the resource, while helping to sustain high standards fisheries by adding value to the landed catch. In order to better manage waste, it is necessary to identify and quantify by-raw material (waste to be repurposed) along theseafood value chain. This project describes the bigeye (Thunnus obesus) fresh tuna market in San Diego using a metabolism approach. Specifically, the goals were to: (1) describe the bigeye tuna supply chain in San Diego, (2) quantify where losses are occurring, and (3) briefly describe opportunities to utilize by-raw materials. The project serves as a proof of concept that applying this method can successfully identify and follow the biomass throughout a particular seafood system. Every step of the value chain was included, from harvest at sea, to the processing facility, to the seafood counter. For the year 2018, this research estimated that the fishery provided 596 metric tons (MT) of fresh seafood to the local market while an additional 187 MT of wild resource was lost along the way with some at sea and some concentrated at the processor. Of the 187 MT of loss, 136 MT of losses happen at sea and consist of catch released alive or dead, lost bait, guts and gills, and 51 MT of bigeye by-raw material are left in the processing facility and comprise head, collar, tail, carcass, skin and bloodline. While the model shows that most of the losses occur at sea and consist of by-catch, it is important to note that by-catch data from the Western and Central Pacific longlining fishery was used as a proxy and may not be representative ofWest Coast fisheries that have different fishing grounds. Therefore, the robustness of this number should be tested in the near future when West Coast by-catch data become available. Bigeye yield is known by the industry to be ca. 50% but because losses are diffused along the value chain only 18% of by-rawmaterial is shown by this study to be found at the processing facility, this includes head and tail currently used as lobster bait or turned into compost. There are a number of additional uses for bigeye by-raw material. To move towards a full utilization of the fish, the industry could target unused and actionableby-raw material such as tuna skin for leather, in addition to exploring new processing and marketing strategies for the lower grade filets that currently are under-sold or eventually discarded. Despite the relatively small size of the San Diego bigeye fishery, the integration of all data streams of the supply chain demonstrated that this approach could be replicated to evaluate by-raw materials in other fisheries or locations. If exploring culinary and non-culinary uses of our wild-caught fish is an important step to move toward greater sustainability, further research at a larger scale as well as a regulatory framework analysis are needed to understand and estimate the impact of a full utilization movement for marine conservation in California.

RationaleIt is imperative to understand how chemical preservation alters tissue isotopic compositions before using historical samples in ecological studies. Specifically, although compound-specific isotope analysis of amino acids (CSIA-AA) is becoming a widely used tool, there is little information on how preservation techniques affect amino acid δ15 N values.MethodsWe evaluated the effects of chemical preservatives on bulk tissue δ13 C and δ15 N and amino acid δ15 N values, measured by gas chromatography/isotope ratio mass spectrometry (GC/IRMS), of (a) tuna (Thunnus albacares) and squid (Dosidicus gigas) muscle tissues that were fixed in formaldehyde and stored in ethanol for 2 years and (b) two copepod species, Calanus pacificus and Eucalanus californicus, which were preserved in formaldehyde for 24-25 years.ResultsTissues in formaldehyde-ethanol had higher bulk δ15 N values (+1.4, D. gigas; +1.6‰, T. albacares), higher δ13 C values for D. gigas (+0.5‰), and lower δ13 C values for T. albacares (-0.8‰) than frozen samples. The bulk δ15 N values from copepods were not different those from frozen samples, although the δ13 C values from both species were lower (-1.0‰ for E. californicus and -2.2‰ for C. pacificus) than those from frozen samples. The mean amino acid δ15 N values from chemically preserved tissues were largely within 1‰ of those of frozen tissues, but the phenylalanine δ15 N values were altered to a larger extent (range: 0.5-4.5‰).ConclusionsThe effects of preservation on bulk δ13 C values were variable, where the direction and magnitude of change varied among taxa. The changes in bulk δ15 N values associated with chemical preservation were mostly minimal, suggesting that storage in formaldehyde or ethanol will not affect the interpretation of δ15 N values used in ecological studies. The preservation effects on amino acid δ15 N values were also mostly minimal, mirroring bulk δ15 N trends, which is promising for future CSIA-AA studies of archived specimens. However, there were substantial differences in phenylalanine and valine δ15 N values, which we speculate resulted from interference in the chromatographic resolution of unknown compounds rather than alteration of tissue isotopic composition due to chemical preservation.

Many species of sharks and some tunas are threatened by overexploitation, yet the degree of overlap between industrial fisheries and pelagic fishes remains poorly understood. Using satellite tracks from 933 industrial fishing vessels and predictive habitat models from 876 electronic tags deployed on seven shark and tuna species, we developed fishing effort maps across the northeast Pacific Ocean and assessed overlap with core habitats of pelagic fishes. Up to 35% of species core habitats overlapped with fishing effort. We identified overlap hotspots along the North American shelf, the equatorial Pacific, and the subtropical gyre. Results indicate where species require international conservation efforts and effective management within national waters. Only five national fleets (Mexico, Taiwan, China, Japan, and the United States) account for >90% of overlap with core habitats of our focal sharks and tunas on the high seas. These results inform global negotiations to achieve sustainability on the high seas.

The development of osmoregulatory and gas exchange organs was studied in larval yellowfin tuna (Thunnus albacares) from 2 to 25 days post-hatching (2.9-24.5 mm standard length, SL). Cutaneous and branchial ionocytes were identified using Na+/K+-ATPase immunostaining and scanning electron microscopy. Cutaneous ionocyte abundance significantly increased with SL, but a reduction in ionocyte size and density resulted in a significant decrease in relative ionocyte area. Cutaneous ionocytes in preflexion larvae had a wide apical opening with extended microvilli; however, microvilli retracted into an apical pit from flexion onward. Lamellae in the gill and pseudobranch were first detected ~ 3.3 mm SL. Ionocytes were always present on the gill arch, first appeared in the filaments and lamellae of the pseudobranch at 3.4 mm SL, and later in gill filaments at 4.2 mm SL, but were never observed in the gill lamellae. Unlike the cutaneous ionocytes, gill and pseudobranch ionocytes had a wide apical opening with extended microvilli throughout larval development. The interlamellar fusion, a specialized gill structure binding the lamellae of ram-ventilating fish, began forming by ~ 24.5 mm SL and contained ionocytes, a localization never before reported. Ionocytes were retained on the lamellar fusions and also found on the filament fusions of larger sub-adult yellowfin tuna; however, sub-adult gill ionocytes had apical pits. These results indicate a shift in gas exchange and NaCl secretion from the skin to branchial organs around the flexion stage, and reveal novel aspects of ionocyte localization and morphology in ram-ventilating fishes.

Cadmium (Cd) is a toxic heavy metal found throughout the environment and one of the top ten toxicants of major public health concern identified by the World Health Organization. In utero Cd exposure causes fetal growth restriction, malformation, and spontaneous abortion; however, the mechanisms by which Cd impacts these outcomes are poorly understood. Cd accumulates in the placenta, suggesting that these negative outcomes may be a consequence of disrupted placental function and placental insufficiency. To understand the impact of Cd on gene expression within the placenta, we developed a mouse model of Cd-induced fetal growth restriction through maternal consumption of CdCl2 and performed RNA-seq on control and CdCl2 exposed placentae. The top differentially expressed transcript was the Tcl1 Upstream Neuron-Associated (Tuna) long non-coding RNA, which was upregulated over 25-fold in CdCl2 exposed placentae. Tuna has been shown to be critical for neural stem cell differentiation. However, within the placenta, there is no evidence that Tuna is normally expressed or functional at any developmental stage. To determine the spatial expression of Cd-activated Tuna within the placenta, we used in situ hybridization as well as placental layer-specific RNA isolation and analysis. Both methods confirmed the absence of Tuna expression in control samples and determined that Cd-induced Tuna expression is specific to the junctional zone. Since many lncRNAs regulate gene expression, we hypothesized that Tuna forms part of the mechanism of Cd-induced transcriptomic changes. To test this, we over-expressed Tuna in cultured choriocarcinoma cells and compared gene expression profiles to those of control and CdCl2 exposed cells. We demonstrate significant overlap between genes activated by Tuna overexpression and genes activated by CdCl2 exposure, with enrichment in the NRF2-mediated oxidative stress response. Herein we analyze the NRF2 pathway and show that Tuna increases NRF2/NRF2 both at the transcript and protein levels. Tuna drives increased NRF2 target gene expression, a result that is abrogated with the use of an NRF2 inhibitor, confirming that Tuna activates oxidative stress response genes through this pathway. This work identifies the lncRNA Tuna as a potential novel player in Cd-induced placental insufficiency.