Yellowfin Tuna Research Articles

The Role of Ultrasound Cavitation Combined with Alcalase Enzyme in Improving the Structural and Antioxidant Attributes of Sulfated Polysaccharide from Yellowfin (Thunnus albacares) Skin

ABSTRACT Alcalase enzyme (1 mg) and ultrasound (400 W) at 0–20 min were applied to obtain sulfated polysaccharides from yellowfin skin. Applying 15 min ultrasound resulted in a 0.12% increase in the rate of recovery yield. The intact structure of polysaccharides was determined by Fourier transform infrared spectroscopy, X-ray diffractometry, and scanning electron microscope. Ultrasound improved the thermal behavior of sulfated polysaccharides by affecting their microstructure, as analyzed by DSC. The color characterization (L*, a*, and b*) of ultrasound-treated samples was found to be superior compared to the control. Applying 15 min led to 16% and 9% enhancing DPPH and ABTS radical scavenging activities along with improving ferric-reducing antioxidant power of the polysaccharide.

Impact of Implementing Ex-Foreign Ship Moratorium Policy on Tuna Fishing Business in Benoa, Bali

Regulation of the Minister of Maritime Affairs and Fisheries number 56 of 2014 and Regulation of the Minister of Maritime Affairs and Fisheries number 10 of 2015 help realize responsible fisheries management and combat Illegal, Unreported, and Unregulated (IUU) Fishing in Fisheries Management Area of ​​the Republic of Indonesia (WPP NRI). The policy of temporarily stopping permits (moratorium) for ships manufactured overseas (ex-foreign vessels) directly impacts fishermen working on ex-foreign vessels in the form of reduced income to loss of livelihoods. The research used a retrospective approach where policy analysis is carried out on the consequences of a policy after the policy is implemented. It is usually referred to as an evaluative analysis model, so it is expected to produce information that can improve the quality of the policies implemented by the government. The study aimed to determine the moratorium's impact on capture fisheries licensing on business activities, especially on fishing effort, catch per unit effort (CPUE), and socioeconomic conditions of fisheries at Benoa Harbor, Bali. This research was conducted from March to October 2022 in the Benoa Harbor Area, Bali. The data in this study were obtained from observation, interviews, questionnaires, and literature/document studies. The moratorium policy for ex-foreign vessels, followed by a ban on transshipment, significantly changed the pattern of trade, particularly for tuna, which was dominated initially by fresh tuna to frozen tuna with a lower value. The longline catches are dominated by Thunnus alalunga, followed by Thunnus maccoyii, Thunnus albacares, and Thunnus obesus. The total of ships in 2014 was 915 units, and only 246 ships remained in 2018. The significant decrease in fish landings in 2015-2017 is a real impact of the moratorium on ex-foreigners in Benoa. The results of the data analysis show that in 2014 the number of attempts was 2,264, which continued to decline until 2018, with only 697 trips.

Molecular Rapid Test for Identification of Tuna Species.

Tuna is an excellent food product, relatively low in calories, that is recommended for a balanced diet. The continuously increasing demand, especially for bluefin-tuna-based food preparations, and its relatively high market price make adulteration by intentionally mixing with other lower-priced tunas more prospective. The development of rapid methods to detect tuna adulteration is a great challenge in food analytical science. We have thus developed a simple, fast, and low-cost molecular rapid test for the visual detection of tuna adulteration. It is the first sensor developed for tuna authenticity testing. The three species studied were Thunnus thynnus (BFT), Thunnus albacares, and Katsuwonus pelamis. DNA was isolated from fresh and heat-treated cooked fish samples followed by PCR. The PCR products were hybridized (10 min) to specific probes and applied to the rapid sensing device. The signal was observed visually in 10-15 min using gold nanoparticle reporters. The method was evaluated employing binary mixtures of PCR products from fresh tissues and mixtures of DNA isolates from heat-treated tissues (canned products) at adulteration percentages of 1-100%. The results showed that the method was reproducible and specific for each tuna species. As low as 1% of tuna adulteration was detected with the naked eye.

Evaluation of the Risk from Potentially Toxic Elements (PTEs) in Italy’s Most Consumed Processed Fish Products

In a balanced diet, regular fish consumption provides positive outcomes for human health. On the other hand, the seafood supply chain faces a significant food safety risk due to the presence of potentially toxic elements (PTEs). In the present study, to assess the risk for Italian consumers, the concentrations of five PTEs, namely lead, chromium, cadmium, mercury, nickel, and aluminum, were determined in the three most consumed preserved fish in Italy: tuna (Thunnus albacares, Katsuwonus pelamis), mackerel (Scomber scombrus) and anchovy (Engraulis encrasicolus). Samples were collected from the national market, and the instrumental analysis was performed by inductively coupled plasma mass spectrometry (ICP-MS). The analyzed PTEs were found in all the species that were investigated. However, after considering the target hazard quotient (THQ) and the hazard index (HI), it was observed that the three fish preserves did not pose any risk of chronic toxicity for the average consumer, even at the highest concentrations detected. However, for significant consumers, mercury detected in tuna samples represented almost 90% of the tolerable weekly intake (TWI) reported by the European Food Safety Authority (EFSA), representing a matter of concern for consumers, particularly regarding developmental neurotoxicity, whose HI exceeded 111%. The acute toxicity of nickel was also considered for significant consumers at the highest concentration detected, and the margin of exposure (MOE) calculated was above 7000, much higher than the value of 30 indicated by EFSA. Due to the lack of data on non-professional carcinogenicity or human intake through foods with low cancer risk, this toxicity was not considered in the analysis of PTEs.

Evidence from interpretable machine learning to inform spatial management of Palau's tuna fisheries

AbstractStatic and dynamic area‐based management tools hold substantial potential to balance socioeconomic benefits derived from fisheries and costs from bycatch mortality of at‐risk species. Palau longline fisheries have high bycatch of at‐risk species including the olive ridley marine turtle and silky and blue sharks. This study analyzed a two decades‐long time series of observer and electronic monitoring datasets from the Palau distant‐water and locally‐based pelagic longline fisheries. An interpretable or explainable machine learning‐based modeling approach was used to derive spatially resolved species‐specific catch rate predictions. These models were conditioned on a suite of potentially informative environmental, bathymetric, ocean‐climate metric, vessel, monitoring system, and set‐specific operational predictors. Overall, there would be limited ecological tradeoffs from focusing fishing effort within primary catch rate hotspots for target bigeye and yellowfin tunas. Mean field prediction surfaces also defined catch rate hotspots for at‐risk species of silky and blue sharks, olive ridley turtle, and pelagic stingray, which did not overlap the hotspots for target species. The predicted target species hotspots, however, overlap olive ridley and pelagic stingray warmspots. Results also identify opportunities for temporally dynamic spatial management to control catch rates of target and bycatch species. Management of fishery operational predictors of fishing depth and soak duration present additional opportunities to balance catch rates of at‐risk bycatch and target species. A transition to employing fleetwide or vessel‐based output controls that effectively constrain the fishery would alter the spatial management strategy to focus on zones with the lowest ratio of at‐risk bycatch to commercial catch. Our findings support evidence‐informed evaluation of spatial management strategies and complementary measures to meet objectives for balancing socioeconomic benefits derived from target species catch with costs to threatened species.

An equatorial mid-Atlantic Ocean archipelago as nursery area for the cookiecutter shark: Investigating foraging strategies of neonates through bite mark inferences.

This study delves into the foraging ecology of the cookiecutter shark (Isistius brasiliensis) in the Saint Peter and Saint Paul Archipelago (SPSPA), assessing bite marks on pelagic fishes collected between March and September 2018. Examination of 200 individuals from five species revealed the shark's predilection for targeting adult fish, ensuring efficient removal of energy-rich tissue layers. However, a notable exception is Thunnus albacares, preyed on predominantly during its juvenile stage, possibly due to vertical spatial segregation. Recent bites were pervasive across species, with wahoo displaying a distinctive pattern. Cookiecutter shark bites predominantly targeted the lateral body portion (>55%) except for yellowfin tuna, which exhibited a preference for the ventral region (95%). The estimated length distribution suggests the SPSPA as a potential nursery area for cookiecutter sharks. Bite mark positions and frequencies may be linked to fish behavior, swimming velocity, and fishing gear strategy, highlighting the complex interplay in pelagic ecosystems.

Genomic resources for the Yellowfin tuna Thunnus albacares.

The Yellowfin tuna (Thunnus albacares) is a large tuna exploited by major fisheries in tropical and subtropical waters of all oceans except the Mediterranean Sea. Genomic studies of population structure, adaptive variation or of the genetic basis of phenotypic traits are needed to inform fisheries management but are currently limited by the lack of a reference genome for this species. Here we report a draft genome assembly and a linkage map for use in genomic studies of T. albacares. Illumina and PacBio SMRT sequencing were used in combination to generate a hybrid assembly that comprises 743,073,847 base pairs contained in 2,661 scaffolds. The assembly has a N50 of 351,587 and complete and partial BUSCO scores of 86.47% and 3.63%, respectively.Double-digest restriction associated DNA (ddRAD) was used to genotype the 2 parents and 164 of their F1 offspring resulting from a controlled breeding cross, retaining 19,469 biallelic single nucleotide polymorphism (SNP) loci. The SNP loci were used to construct a linkage map that features 24 linkage groups that represent the 24 chromosomes of yellowfin tuna. The male and female maps span 1,243.8cM and 1,222.9cM, respectively. The map was used to anchor the assembly in 24 super-scaffolds that contain 79% of the yellowfin tuna genome. Gene prediction identified 46,992 putative genes 20,203 of which could be annotated via gene ontology. The draft reference will be valuable to interpret studies of genome wide variation in T. albacares and other Scombroid species.

Daya Saing Ekspor Ikan Tuna Indonesia di Pasar Global

Revealed Comparative Advantage (RCA) analysis is a key tool in assessing a country's competitiveness compared to others. This study uses RCA to measure Indonesia's comparative advantage in the global tuna market. The calculated RCA values show Indonesia's superiority in tuna production and exports, especially with a focus on fresh or chilled yellowfin tuna (Thunnus albacares) with HS Code 030232. The RCA values for Indonesia, Panama, the Philippines and the Netherlands are 200, 150, 50, 350, and 400, respectively. These results confirm that Indonesia has a comparative advantage in the international tuna market, which is supported by abundant natural resources, a large fishing workforce, and a history of successful tuna exports. Despite this, challenges remain, including overfishing, the impacts of climate change, and illegal, unreported, and unregulated (IUU) fishing. The decline in tuna production in Indonesia demands better fisheries management and international cooperation to address unsustainable practices. The Indonesian government's commitment to conservation is visible in the Tuna, Skipjack and Tuna Fisheries Management Plan. Overall, Indonesia's vibrant tuna export industry, supported by extensive marine resources, a large international market and robust infrastructure, shows significant potential. The government's commitment, combined with ongoing efforts to increase competitiveness through increased productivity, product quality, diversification and global promotion, positions Indonesia to strengthen its role as a major player in the global tuna export market.

Multi-omics analysis revealed the differences in lipid metabolism of the gut between adult and juvenile yellowfin tuna (Thunnus albacares).

Tuna has a cost-effective energy supply to support the regional endothermic and high-speed swimming performance. The gut symbiotic microbiotas and their metabolites play essential roles in tuna's diet digestion, absorption, and energy acquirement, which are often highly related to the ontogenetic development of tuna. We compared gut microbial compositions and metabolites, as well as mRNA expression of the intestine between juvenile and adult yellowfin tuna using 16S rRNA sequencing, metabolomic and transcriptomic, respectively. The results revealed that adults had a significantly higher microbial diversity and abundance of Acinetobacter than juveniles. Regarding the gut microbiota-derived metabolites, fatty acids, especially glycerophospholipid and sphingolipid, were significantly enriched in adults than in juveniles. Moreover, the short-chain fatty acid (butyrate and isobutyrate) contents were significantly higher in adults than in juveniles. To find the relationship between gut microbiotas and host physiology, intestinal transcriptome analysis demonstrated that the enriched pathways of differential expression genes (DEGs) in adult tuna were the lipid metabolism pathway, including "fat digestion and absorption," "cholesterol metabolism," "steroid hormone biosynthesis," "glycerolipid metabolism," and "glycerophospholipid metabolism." However, protein digestion and absorption and pancreatic secretion pathways were significantly enriched in the juveniles. The conjoint analysis indicated that the enriched pathways of both differential metabolites (DMs) and DEGs were remarkably related to the regulation of glycerophospholipids metabolism in adult tunas. This study highlights the role of gut microbiotas in fish nutrition metabolism. These findings provide new insights into the view of ontogenetic shifts of gut microbiotas and their metabolites on host health and gut function in endothermic and high-speed swimming marine fish species.

Variabilitas musiman terhadap hasil tangkapan Tuna Madidihang (Thunnus albacares)

Fishermen in North Buru often depend on seasonal changes in tuna madidihang abundance to plan their fishing operations. However, a more comprehensive understanding of how this seasonal variability affects catches and its implications for fisheries management is still an important research subject. The research was conducted in Wailihang Village, Waplau District, North Buru Regency, between October and December 2022. The observational method was used for this study, where available and precise time series data owned by the Indonesian Community and Fisheries Foundation (MDPI) was collected. The collected data is the number of catch productions (kg) and the total length of fish (cm) from each haul. Yellowfin tuna production tends to fluctuate, with the highest catch (CPUE) occurring in September (63.8%) and the lowest in June (34.2%). The west season and east seasons have a total catch of 556 fish (45.42%), with 382 fish (31.21%) caught during the east season and 174 fish (14.22%) caught during the west season. The distribution of fish length varies in the east season compared to the west season. The west season catches more fish, but they are generally small-sized, while during the east season, large fish dominate, with the highest presentation (38.67%).

Feeding behavior of yellowfin tuna around two insular regions of the western Atlantic Ocean.

The yellowfin tuna is a very abundant tropical tuna species in the western equatorial Atlantic Ocean and an important fishery resource for the Brazilian tuna fleet. In this study we performed stable isotope analysis to better understand the spatial trophodynamics and dietary changes in yellowfin tuna around two insular marine protected areas in Brazil. A total of 65 yellowfin tuna specimens measuring between 47 and 138 cm LT (total length) were sampled around the archipelagos of Fernando de Noronha (FNA; n = 34) and Saint Peter and Saint Paul (SPSPA; n = 31) between July 2018 and September 2019. Bayesian mixing models and generalized additive models were used to investigate the contributions of four different prey items (zooplankton, cephalopods, fish larvae, and flying fish) to yellowfin tuna diet in each area and their potential changes in relation to predator growth. The four prey items were found to have different overall contributions between the two studied areas, with zooplankton being the most important prey in FNA, whereas flying fish was the most relevant prey to the species' diet in SPSPA. Significant changes in the species diet by size were also found, with fish smaller than 90 cm (TL) having a more generalist diet and larger animals relying more on consuming larger and more nutritious prey (i.e., flying fish). Our results suggest that these two marine protected areas play an important role in ocean dynamics, providing important and different foraging grounds for the development of this predator species.

Highly active fish in low oxygen environments: vertical movements and behavioural responses of bigeye and yellowfin tunas to oxygen minimum zones in the eastern Pacific Ocean

Oxygen minimum zones in the open ocean are predicted to significantly increase in volume over the coming decades as a result of anthropogenic climatic warming. The resulting reduction in dissolved oxygen (DO) in the pelagic realm is likely to have detrimental impacts on water-breathing organisms, particularly those with higher metabolic rates, such as billfish, tunas, and sharks. However, little is known about how free-living fish respond to low DO environments, and therefore, the effect increasing OMZs will have cannot be predicted reliably. Here, we compare the responses of two active predators (bigeye tuna Thunnus obesus and yellowfin tuna Thunnus albacares) to DO at depth throughout the eastern Pacific Ocean. Using time-series data from 267 tagged tunas (59,910 days) and 3D maps of modelled DO, we find that yellowfin tuna respond to low DO at depth by spending more time in shallower, more oxygenated waters. By contrast, bigeye tuna, which forage at deeper depths well below the thermocline, show fewer changes in their use of the water column. However, we find that bigeye tuna increased the frequency of brief upward vertical excursions they performed by four times when DO at depth was lower, but with no concomitant significant difference in temperature, suggesting that this behaviour is driven in part by the need to re-oxygenate following time spent in hypoxic waters. These findings suggest that increasing OMZs will impact the behaviour of these commercially important species, and it is therefore likely that other water-breathing predators with higher metabolic rates will face similar pressures. A more comprehensive understanding of the effect of shoaling OMZs on pelagic fish vertical habitat use, which may increase their vulnerability to surface fisheries, will be important to obtain if these effects are to be mitigated by future management actions.

Dynamics of Chlorophyll-a Concentration in Ternate Island Waters and Its Effect on Yellowfin Tuna Production

This research was conducted from May to August 2023, with the aim of assessing the distribution of chlorophyll-a concentration and its effect on yellowfin tuna production in Ternate Island waters. The use of experimental fishing methods in collecting research data and data analysis in the form of abundance analysis, exponential regression, cross correlation, and General Aditive Models is expected to answer the research objectives. The results showed that the fluctuation of yellowfin tuna fish catch was similar to the abundance of fish stocks with the highest catch in June (14 229 kg) followed by July (11 142 kg), August (10 764 kg) and May (8 001 kg). The catch of yellowfin tuna fish is spread over a range of chlorophyll-a concentrations between 0.06 mg m-3 to 0.32 mg m-3, with an average monthly chlorophyll-a concentration of 0.22 mg m-3. Chlorophyll-a conditions in Ternate Island waters are quite fluctuating and significantly affect the catch of yellowfin tuna fish with a very strong correlation coefficient of 0.87. The results of General Aditive Models analysis found that the chlorophyll-a concentration value for potential yellowfin tuna fishing areas is > 0.01 mg m-3 with a correlation distance or time leg is in week 15.

Diet composition and feeding habits of yellowfin tuna Thunnus albacares (Bonnaterre, 1788) from the Bay of Bengal

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 (<80 cm FL) is one group. Crustaceans was the most frequently eaten prey in that group followed by cephalopods and teleostea. The second group consists of two length groups medium (81–120 FL), and larger (>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%).

The effect of yellow and red illuminations on the swimming behaviour, mortality and growth rates of yellowfin tuna juveniles (Thunnus albacares)

The effect of yellow and red illuminations on the swimming behaviour, mortality and growth rates of yellowfin tuna juveniles (<i>Thunnus albacares</i>)

Biological Aspects of Yellowfin Tuna in Bone Gulf Waters, Indonesia

The aim of this study was to examine the composition, growth patterns and condition factors of yellowfin tuna caught in Bone Gulf waters. Sample collection was carried out in July – November 2018 at two stations, i.e., station 1 in Cimpu Luwu Regency and station 2 at the Lonrae Fish Landing Site, Bone Regency. At station 1, 10,366 individuals were caught, with an average size of 81.19 cm in length and of 14.43 kg in weight. Station 2 had a larger average size, i.e., 97.14 cm in length and 27.79 kg in weight. The results of the analysis of tuna growth patterns at station 1 and station 2 showed a value of b &lt; 3, indicating negative allometric growth. This means that the weight gain of the species was slower than its length gain. The average value of the condition factor was 1.03±0.25 for station 1 and 1.07±43 for station 2. These values varied according to temporal variation and fish size.

Toward Swimming Speed Optimization of a Multi-Flexible Robotic Fish With Low Cost of Transport

Due to the complex mechanism and fabrication process of flexible materials, it remains extremely challenging for a flexible robotic fish to achieve fast and efficient locomotion. In this article, taking advantage of the passive bending and energy storage properties of flexible materials, we propose an untethered robotic fish with multiple flexible joints to achieve high performance and low Cost of Transport (COT). First, combining rigid links and flexible materials, a compact flexible tail with a simple and efficient structure is proposed. Next, the pseudo-rigid body theory is applied to analyze the deformation of passive joints, and a full-state dynamic model is established. More importantly, an optimization method by adjusting the phase differences of the passive joints is used to obtain high aquatic performance. Finally, extensive simulations and experiments validate the effectiveness of the proposed method, and the robotic fish can achieve a maximum speed of 1.63 body length (BL) per second and a minimum COT of 4.8 J/m (2.87 J/m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot$</tex-math> </inline-formula> kg). Compared with the multi-joint robotic fish with a similar design, the COT is reduced by up to 81.05% with the basically same aquatic ability. Excitingly, the flexible robotic fish can achieve a COT of 7.36 J/m at 1.23 BL/s, which is 15.72%-36.34% lower than that of the bluefin tuna and is within the range of yellowfin tuna, offering valuable insight into high speed and long endurance applications for underwater robots. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> –This paper is motivated by the design and optimization of an efficient bionic flexible underwater robot with high aquatic abilities, which is conducive to aquatic tasks that require long-time and long-distance sailing, such as underwater topographic exploration, submarine archaeology, and underwater search and rescue. Existing studies of free-swimming bionic underwater robots usually focus on the improvement of swimming speed and rarely consider achieving both high swimming performance and low energy cost. Thus, this paper proposes a bionic underwater robot design with two joints made of flexible materials on the tail to address the problem. Based on detailed analyses of the hydrodynamic force and flexible joint deformation, we propose an effective optimization method for swimming performance. A series of simulations and experiments suggest that the mechatronic design and optimization method are practical and valid. Hopefully, our design and method can provide theoretical guidance for engineers to design and optimize robots with flexible joints.

Characterization of trypsin enzyme extracted from intestines of yellowfin tuna (Thunnus albacares) and bigeye tuna (Thunnus obesus) from Indonesian seawater

Recently, there has been a major concern about fisheries waste produced by tuna processing factories. There are many ways to handle the waste from tuna processing factories, specifically the tuna viscera which contains the stomach, pyloric caeca, kidneys, and intestines. The tuna viscera have been known as a source of digestive enzymes, one of them is a protease, including trypsin. The objective of this research was to analyze the enzymatic characteristic of trypsin extracted from two different tuna species. In this study, the trypsin extracted from the intestines of yellowfin and bigeye tuna was characterized by analyzing its enzyme activity as well as optimum temperature and pH, protein concentration, kinetic studies, and molecular weight. The results reveal that the enzyme activity and protein concentration observed in bigeye tuna (Thunnus obesus) were significantly higher than in yellowfin tuna (Thunnus albacares). In addition, trypsin bigeye and yellowfin tuna had the optimum temperature and pH from both crude extracts within the range of 50-60˚C and 7-8, respectively. Moreover, the molecular weights of trypsin enzymes extracted from yellowfin (T. albacares) and bigeye tuna (T. obesus) were 29 kDa.

Evaluation of fatty acids and carnitine as biomarkers of PFOS exposure in biota (fish and dolphin) from Galveston Bay and the northwestern Gulf of Mexico

Perfluorooctane sulfonate (PFOS) is a ubiquitous pollutant that elicits a wide range of toxic effects in exposed biota. Coastal zones in highly urbanized or industrial areas are particularly vulnerable to PFOS pollution. At present, information is lacking on biomarkers to assess PFOS effects on aquatic wildlife. This study investigated the efficacy of l-carnitine (or carnitine) and fatty acids as biomarkers of PFOS exposure in aquatic biota. The levels of PFOS, total and free carnitine, and 24 fatty acids (measured as fatty acid methyl esters or FAMEs) were measured in the liver, and muscle or blubber, of fish and dolphins sampled from Galveston Bay and the northern Gulf of Mexico (nGoM). Overall, bottlenose dolphins (Tursiops truncatus) had the highest hepatic PFOS levels. Galveston Bay fish, gafftopsail catfish (Bagre marinus), red drum (Sciaenops ocellatus), and spotted seatrout (Cynoscion nebulosus), had hepatic PFOS levels ∼8-13× higher than nGoM pelagic fish species, red snapper (Lutjanus campechanus) and yellowfin tuna (Thunnus albacares). The multivariate analysis of PFOS liver body-burdens and biomarkers found carnitine to be a more modal biomarker of PFOS exposure than FAMEs. Significant positive correlation of hepatic PFOS levels with total carnitine was evident for biota from Galveston Bay (fish only), and a significant correlation between PFOS and total and free carnitine was evident for biota from the nGoM (fish and dolphins). Given the essential role of carnitine in mediating fatty acid β-oxidation, our results suggest carnitine to be a likely candidate biomarker of environmental PFOS exposure and indicative of potential dyslipidemia effects.

Sample contamination explains evidence of close kin proximity in yellowfin tuna (Thunnus albacares) in the Western and Central Pacific Ocean

Anderson et al.’s 2019 paper ‘Close Kin Proximity in Yellowfin Tuna (Thunnus albacares) as a Driver of Population Genetic Structure in the Tropical Western and Central Pacific’ provided observations of genetically related individuals among sampled yellowfin tuna. Resampling of some individuals from the original study produced very different sequencing results when compared with the original dataset, one possible explanation of which is cross-contamination among the original samples. Re-analyses produced no indication of strong population structure, including a very slightly and consistent heterozygosity deficit with only one statistically significant pairwise FST value of 0.002. We identified only one pair of genetically similar individuals that could still be an artefact of lingering contamination. These new results therefore support a highly connected population of yellowfin tuna in the study area, although we do not rule out the potential for local adaptation driven by non-observed loci or genetic sub-structure operating at more contemporary scales.