Search

The vulnerability of fisheries to climatic variability can be measured through the capacity of species to adapt to environmental change. It was also analyzed based on the analysis of fish production and susceptibility. Yellowfin tuna is one of the main commodities in the Palabuhanratu fishing port of Indonesia. The condition of yellowfin tuna fisheries needs to be studied due to the vulnerability of existing fishing activities and climate change parameters. This research was conducted at the Palabuhanratu fishing port, Sukabumi, West Java, Indonesia. Productivity and susceptibility analysis was used to determine the value of species vulnerability to fishing activities and based on the climatic variability. This study aims to analyze the vulnerability level of capture fisheries, especially for yellowfin tuna, to the Sea Surface Temperature dynamics through the analysis of productivity and susceptibility. The research will support capture fisheries management based on vulnerability analysis by providing a novel integrated analysis between productivity, susceptibility, and oceanographic data. The result of the productivity score was 2.11, and the susceptibility score was 2.17. It means that yellowfin tuna landed at the Palabuhanratu fishing port was threatened by vulnerability, but yellowfin tuna can recover and survive properly against fishing activities. The vulnerability score of yellowfin tuna was 1.6, which was classified as low vulnerability. The relationship between climate change parameters, namely sea surface temperature, and yellowfin tuna parameter, has a low-medium correlation and has an inverse relationship. Sea surface temperature can affect the development of larvae and eggs and the availability of yellowfin tuna food. By knowing the vulnerability of the yellowfin tuna fishery, sustainable fisheries management can be carried out both based on the regulation of the fishing season and the level of utilization.

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

New data on captures of mirror dory Zenopsis nebulosa and bluefin tuna Thunnus orientalis in the coastal waters of Primorye (Peter the Great Bay and northward from Povorotny Cape) are presented.

Distinguishing the cause and magnitude of capture-related mortality (CRM) in fishes is important for effective management. To better understand CRM in yellowfin tuna (Thunnus albacares) released in the recreational troll fishery off the United States east coast, 48 fish (76–127 cm curved fork length, CFL) were monitored for up to 86 days postrelease with survivorship pop-up satellite archival tags. Recovered data indicated 40 fish were alive at the time of tag detachment and eight died, including six from predation, from 0 to 30 days postrelease. Survival model variants were constructed to independently estimate the rates of immediate capture and handling (CH), postrelease (PR), total CRM (CH + PR), and natural mortality (M) for small (≤103 cm CFL) and large (>103 cm CFL) fish under different hypotheses and causes of mortality. CH was low (0%–8%) for both size classes but predation was an important component of PR, particularly in the small size class. Total CRM was 51% (95% CI: 26%, 81%) for small and 8% (95% CI: 2%, 30%) for large fish.

In this paper, we develop and study a mathematical model for the dynamics of Scomber colias and Thunnus thynnus prey-predator with parasitic helminths. We search to analyze a bioeconomic model in which both susceptible and infected prey populations Scomber colias are exposed to the predator Thunnus thynnus, with varying degrees of exposure. However, the predator feeds preferentially on the most numerous prey types. This implies a kind of switching from the susceptible class to the infected class, and vice versa, as these two types of prey change in numerical superiority. So, the positivity, boundedness, equilibria, stability, and bioeconomic equilibrium are studied. Some numerical simulation of stability is cited. For giving a high yield and keeping the Scomber colias and Thunnus thynnus populations away from extension, we use the Maximum Principle of Pontryagin.

Sex-identification DNA markers are useful tools for sexing organisms that lack externally visible sexual dimorphism, and thus, they provide biological information for ecological and evolutionary studies. Tunas of the genus Thunnus (Scombridae), which comprises 8 species, lack sexual dimorphism of external morphology or coloration. In this study, we applied recently developed genotypic sex-identification markers for Pacific bluefin tuna to other tuna species to evaluate their effectiveness in sex identification. A sex-identification marker named ‘primer pair II’ demonstrated relatively high effectiveness in all tuna species, except southern bluefin tuna. Primer pair II was further tested in 209 albacore individuals collected during the scientific observer program onboard Japanese commercial long-line vessels, and it demonstrated robust performance for genotypic sex identification. The sex ratio of this albacore sample (1:1.4) significantly deviated from the expected 1:1 with the dominance of males, and the mean body size of males was higher than that of females. As all cross-species amplifications of the male-specific markers, except those for the southern bluefin tuna, were male-heterozygous polymorphisms, it is likely that a male-heterozygous sex-associated region exists in the Thunnus genome. The evolution of sex-determination systems in tunas was analyzed by ancestral state reconstruction, which showed that a common ancestor, before the evolution of the genus, possessed the male-heterozygous sex-associated genome region.

The trophodynamics of Thunnus albacares (Bonnaterre, 1788) from the western Bay of Bengal was studied during 2012 – 2015. Feeding intensity revealed that 34.6 % of the fishes had empty-trace stomachs, 52.77% of the fishes had quarter full-half full stomachs and 12.44% of the fishes had three fourth full-gorged stomachs. Feeding intensity increased with an increase in body size of the fishes with high prey to predator weight ratios and with a third of the fishes above 160 cm fork length possessing three fourth full-gorged stomachs. Cephalopods (47%) dominated the prey constituents, followed by semi digested finfishes and shellfishes (28%), finfishes (16%) and crustaceans (9%). Significant shifts in prey items were observed with an increase in fish size. Though squids were predominant in the diet, however, with the increase in size, feeding shift has clearly been observed towards finfishes. Feeding preferences did not vary between sexes. Annual and seasonal similarities were recorded in their food and feeding habits. Prey-specific abundance indicated a relative specialized feeding pattern with high occurence of species belonging to the orders Teuthidae and Perciformes. Levins Standardized Niche Breadth Index of 0.16 indicated limited niche width in the feeding strategy of Thunnus albacares.

This study aimed to reconstruct temperatures experienced during the larval period by adult Pacific bluefin tuna Thunnus orientalis using high-resolution otolith stable oxygen isotope (δ18O) analysis. A novel otolith sample preparation protocol for secondary ion mass spectrometry (SIMS) analysis developed in this study reduced the background noise of SIMS measurements, enabling analyses of >10 times higher resolution around the otolith core compared to previous studies using conventional isotope ratio mass spectrometry (IRMS). The values obtained from SIMS were compared to those obtained by microvolume δ18Ootolith analysis using micromilling and conventional continuous-flow IRMS (CF-IRMS). There was a systematic offset (average 0.41‰ with SIMS resulting in lower values) most likely caused by matrix effects on SIMS δ18Ootolith values that can be calibrated using a strong linear relationship between SIMS and CF-IRMS measurements (r2 = 0.78, p < 0.001). The core-to-edge δ18Ootolith of 5 Pacific bluefin tuna revealed fine-scale seasonal variations in water temperature agreeing with known migration patterns. In addition, the ambient water temperature experienced during larval stages (about 10-20 d post hatch) estimated from otolith core δ18O ranged from 26.7 to 30.7°C, overlapping with temperatures associated with the occurrence of larval Pacific bluefin tuna. Combining SIMS and microvolume CF-IRMS δ18O otolith analyses offers a microscale examination of fish ecology that is not possible with conventional IRMS techniques. This novel method is particularly useful for understanding the early life history of fish that may be affected by climate change and reconstructing a well-resolved migration history for fish species that have small otoliths and/or narrow growth increments.

The current practice condition of fish processing will generate some amounts of byproducts such as skin waste. These fish processing by-products can be considered as an alternative raw material for the preparation of high protein ingredients such as gelatin. Gelatin extraction from the skin of yellowfin tuna (Thunnus albacares) was conducted by the acid process. Afterwards, the fish gelatin was mixed with cinnamon (GECP) and roselle powder (GERP) to enhance the physicochemical and functional properties of gelatin. The effects of the addition of cinnamon (GECP) and roselle powder (GERP) on the physicochemical and the functional properties such as tensile strength, hardness, viscosity, water holding capacity, oil holding capacity, total flavonoid, total phenolic, total antioxidant and flavor compounds of enriched gelatin (GECP and GERP) from tuna skin were evaluated and compared with control (without the addition of cinnamon and roselle powder). The gelatin exhibited excellent tensile strength, WHC, OHC, total flavonoid, total phenolic, and antioxidant in the presence of cinnamon and roselle powder rather than control (without addition) (p

Scombrids are the important component of pelagic fishery resources which include 54 species under 15 genera commonly known as mackerels, bonitos, and tunas. Due to the high commercial value attained, there are real chances of fraudulent substitution by species of inferior value. DNA based species identification methods can be applied to detect product adulteration, as well as to better contribute to the conservation and management of these species by providing accurate species identification independently of the age of the individuals or the tissue processed. In this study, a total of 15 commercially important scombrid species from Indian waters were analyzed. Due to the inadequacy of mitochondrial COI barcoding gene in discriminating between some Thunnus species, cytochrome b sequences were used instead. For all the 15 species, we propose a DNA character-based keys which uses a diagnostic combination of nucleotides and respective probes, including the first character-based keys and probes to differentiate between Thunnus albacares and T. obsesus.

Tuna dark meat is a major edible by-product obtained from tuna cannery which is currently under-utilized or opted for the preparation of low-end products. Effective utilization of this marine biomass to bioactive peptides is a promising option facilitating numerous food and nutraceutical applications. Process optimisation studies for the extraction of antioxidant peptides from cooked dark meat of Thunnus albacares using RSM, indicated a papain based hydrolytic condition of 0.98% E/S (w/w), 240 min hydrolysis time as desirable under a pre-optimized temperature and pH of 60 °C and 6.5, respectively. Further detailed characterization viz., nutritional profile, molecular weight, surface morphology, thermal and spectral characteristics, physico-chemical properties, thermal/pH stability and in-vitro digestibility studies of the optimized antioxidant peptide was performed. Nutritional evaluation indicated its abundance in protein with balanced aminoacid profile and explored its richness in glutamic acid, aspartic acid, lysine and leucine. Molecular weight pattern indicated a major distribution (45%) of peptides in the size range of

An APH-22 vertical-takeoff-and-landing hexacopter was used to collect aerial images of schools and individuals of juvenile Atlantic bluefin tuna (ABFT; Thunnus thynnus) at the sea surface in the southern Gulf of Maine. Quantitative measures of fish length, width, and inter-fish spacing were obtained from these images by applying calibration settings and performance measures from calibrating, testing, and evaluating the onboard motion and altimeter sensors and the digital camera and lenses. The accuracy and precision of the onboard motion sensors, camera, and lens calibrations were sufficient to provide length measurements to sub-centimeter precision, but the altimeter performance was least reliable and required additional information, such as images of known-sized objects during each flight, to provide measurements at the accuracy and precision needed for data to be incorporated in fisheries management. The APH-22 was ideal for acquiring images of ABFT individuals and schools and may be a useful tool for remotely monitoring the behavior and body condition of these elusive animals.

The yellowfin fish and terubuk were still rarely used in Papua. This study aimed to determine the physicochemical properties of complementary feeding biscuit formulated with yellowfin fish flour and terubuk flour to improve the nutritional status of children in Papua. A completely randomized single factor-experimental study by using three formulations of yellowfin fish flour and terubuk flour, F1 (1:3), F2 (1:1), and F3 (3:1) was conducted. The carbohydrate content was analyzed with by the difference method, fat by Soxhlet method, protein by Kjeldahl method, fiber by gravimetry method, iron and phosphorus by spectrophotometry method. The physical properties in terms of density, reconstitution and texture were conducted. Sensory evaluation was conducted to determine the acceptance of complementary feeding biscuits. Data were analyzed using the One-Way ANOVA test, Kruskall-Wallis test, Tukey test and Mann-Whitney test. Complementary feeding biscuits F1, F2 and F3 contained energy (435.58; 426.85; 436.71 kcal), protein (13.86; 15.75; 17.33 g), carbohydrate (23.19; 24.79; 20.45 g), fat (20.58; 20.40; 20.62 g), fiber (26.22; 20.63; 25.25 g), iron (3.76; 4.03; 3.68 mg), and phosphorus (267.70; 266.36; 275.79 mg). Complementary feeding biscuits had the following physical properties: density (0.64; 0.68; 0.70 g/mL), reconstitute test (20; 20; 25 mL) and texture test (468.78; 299.55; 408.05 gf). The complementary feeding biscuit was accepted by the panelists. The recommended serving size of complementary feeding biscuit with yellowfin fish flour and terubuk flour was 45 g or four pieces of biscuit needed to fulfill the required 30% of children’s protein per day

Fish skin gelatin can be developed as a raw material for developing biodegradable packaging such as edible film. The present study was to investigate the feasibility of the combination of fish gelatin and addition of roselle powder (GFRP), cinnamon powder (GFCP) and cinnamon essential oil (GFCEO) in producing edible film and to determine protective effect to food product e.g. bread on the physicochemical properties of the active packaging edible films. All the films were analyzed for their physicochemical properties and its observation as the active packaging for bread. It was observed that the addition of roselle powder, cinnamon powder and cinnamon essential oil gave a better result in edible film properties than control (without addition). Principal Component Analysis (PCA) revealed the distinction among the physicochemical characteristic of GFRP, GFCP and GFCEO. This study also mapped the several physicochemical characteristics of different edible film as packaging treatment.

In the present investigation, bigeye tuna (Thunnus obesus) skin waste was utilized for the extraction of gelatin. Physico-chemical, rheological, and surface-active properties of the obtained gelati...

The diet of albacore Thunnus alalunga from their spawning ground in the waters of Mauritius was investigated. The stomach contents of 249 albacore individuals, caught by industrial longliners and a...

Estimates of age and growth of yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tuna remain problematic because validation of growth zone deposition (opaque and translucent) has not been properly evaluated. Otolith growth structure (zone clarity) can be poorly defined for tropical tunas, but the use of bomb radiocarbon dating has validated age estimates to 16–18 years for yellowfin and bigeye tuna. Use of the radiocarbon decline period — defined by regional coral and otoliths — provided valid ages through ontogeny. Yellowfin tuna aged 2–18 years (n = 34, 1029–1810 mm FL) and bigeye tuna aged 3–17 years (n = 12, 1280–1750 mm FL) led to birth years that were coincident with the bomb radiocarbon decline. The results indicate there was no age reading bias for yellowfin tuna and that age estimates of previous studies were likely underestimated for both species.

The paper presents an overview of data based on the analysis of published information concerning the transoceanic migrations of lampreys (Petromyzontidae), sharks (Selachii), and actinopterygian fishes (Actinopterygii). A classification of transoceanic migrations, including eight various types depending on their characteristic features, is proposed. It is shown that transoceanic migrations are rather an exclusion than a norm, even in such good oceanic swimmers as tunas of g. Thunnus and marlins (Istiophoridae).

Tuna fishmeal industrial waste is largely fish oil. Tuna oil is a source of polyunsaturated acid (PUFA), especially omega-3 fatty acids namely docosahexaenoic acid (DHA, C22: 6 Ω-3) and eicosapentaenoic acid (EPA, C20: 5 Ω-3). This study examined the administration of different types and concentrations of adsorbents utilized in the tuna fishmeal industry waste treatment. The study was designed utilizing 2 factorial complete random designs, namely adsorbent types (bentonite, zeolite and activated charcoal) and adsorbent concentrations (5%, 10%, and 15%). Parameters analyzed were clarity (L value), free fatty acids (ALB) and peroxide value. Analysis of fatty acids composition was carried out on fish oil with the best treatment. The analysis results exhibited that the interaction between adsorbent type and concentrations had a significant effect on the level of clarity (L value) and the amount of peroxide oil in the bleached fish, and had no significant effect on free fatty acid levels (ALB). The calculation result of the best treatment of tuna byproducts is the 10% zeolite concentration. It exhibited a clarity value of 36.50, acid value 0.25 mg KOH / g, ALB content 0.17% (oleic), and peroxide value 2.12 meq / kg . Zeolite has a highly structured pore, and the composition of Si/Al represents an active surface capable to be in contact with degradation compounds in fish oil. The composition of fatty acids from the byproducts oils of the post-treatment tuna fishmeal exhibits increased EPA by 12.03% and DHA by 18.25%. However, unsaturated fatty acids exhibited a decrease. SFA decreased by 36.19%, MUFA by 29.73%, and PUFA by 34.08%. The total unsaturated fatty acids (MUFA + PUFA) were 63.81%.

Bigeye tuna ( Thunnus obesus) is an important fish species worldwide due to its desirable flavour and rich nutrition. Cold chain logistics is one of the most common methods to store and sell bigeye tuna ( Thunnus obesus). The purpose of this study was to investigate how bigeye tuna ( T. obesus) deteriorate during simulated cold chain logistics with fluctuating temperatures by monitoring the quality changes and water distribution. The physical and chemical results showed that the sensory score, texture profile analysis (TPA), and water holding capacity (WHC) decreased, while total volatile basic nitrogen (TVB-N), K value, aerobic plate counts (APC), and psychrotrophic bacterial counts increased with fluctuating temperatures during 132 h. Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) detection showed that the T21 (trapped water) and proton density decreased, while T22 (free water) decreased initially and then increased, indicating continuous water loss and water migration during storage. Principal component analysis (PCA) revealed that springiness, hardness, chewiness, T21, and sensory score were correlated with each other ( p 2transverse relaxation time was established. Besides, temperature fluctuation (batch 3) accelerated the deterioration of bigeye tuna according to the comprehensive score of PCA. Results were based on LF-NMR which can be used to monitor quality changes in a fast non-invasive manner.

Kajikia audax, Thunnus albacares, Katsuwonus pelamis, and Auxis spp. occupy high and middle-level trophic positions in the food web. They represent important sources for fisheries in Ecuador. Despite their ecological and economic importance, studies on pelagic species in Ecuador are scarce. This study uses stable isotope analysis to assess the trophic ecology of these species, and to determine the contribution of prey to the predator tissue. Isotope data was used to test the hypothesis that medium-sized pelagic fish species have higher δ15N values than those of the prey they consumed, and that there is no overlap between their δ13C and δ15N values. Results showed higher δ15N values for K. audax, followed by T. albacares, Auxis spp. and K. pelamis, which indicates that the highest position in this food web is occupied by K. audax. The stable isotope Bayesian ellipses demonstrated that on a long time-scale, these species do not compete for food sources. Moreover, δ15N values were different between species and they decreased with a decrease in predator size. Resumo Kajikia audax, Thunnus albacares, Katsuwonus pelamis e Auxis spp. ocupam posições tróficas intermedias e/ou elevadas nas cadeias alimentares. Estas espécies representam um importante recurso pesqueiro no Ecuador. Apesar da sua importância económica e ecológica, estudos nestas espécies pelágicas no Ecuador são raras. Este estudo usa isótopos estáveis para avaliar o seu nível trófico de modo a determinar a contribuição das suas presas para os tecidos destes predadores. Dados dos isótopos foram usados para testar a hipótese de que estas espécies de peixes pelágicos possuem valores mais elevados de δ15N do que daqueles das presas consumidas, e que não existe uma sobreposição entre os valores de δ13C e δ15N. Resultados mostram que valores mais elevados de δ15N para K. audax, seguidos por T. albacares, Auxis spp. e K. pelamis, indicam que a posição mais elevada na cadeia alimentar é ocupada por K. audax. Elipses Bayesianas de isótopos estáveis demonstram que, a uma escala de longo-termo, estas espécies de peixes não competem pelos recursos. Adicionalmente, os valores de δ15N são diferentes entre espécies de peixe estudadas e estes valores decrescem com a diminuição do tamanho do predador.

This research is focused on optimizing high-pressure processing (HPP) for decreasing weight loss of albacore steaks (Thunnus alalunga) while retaining as much as possible the quality of fresh fish. After HPP treatments (0.1–500 MPa, 2 min), samples were stored (24 h, 4°C) and then analyzed (weight loss, color, texture, appearance, water holding capacity, salt-soluble protein content, and lipid oxidation). Weight loss increased from 50 to 150 MPa, without other substantial modification. Above 200 MPa, HPP treatment caused a progressive weight loss reduction. 200 MPa decreased weight loss by 41.6% with respect to 150 MPa, without noticeable changes in color, texture, appearance, or lipid oxidation. 250 MPa decreased weight loss by 50.1% compared to the controls but produced minor changes in color. 500 MPa provoked the maximum reduction of weight loss with respect to the controls (59%), although it caused marked differences in all quality parameters, which would affect consumer acceptance.

The age of sexual maturity of the Atlantic bluefin tuna (Thunnus thynnus; ABFT) is a reference point for stock assessment and management. The International Commission for the Conservation o...

Ovaries of bluefin tuna, Thunnus thynnus, from organisms measuring 247.62 ± 3.54 cm fork length collected within the Mexican Exclusive Economic Zone in the Gulf of Mexico, were examined. Th...

Fish collagen is gaining immense interest because the use of mammalian collagen is restricted due to disease transmission and religious issues. So, collagen was extracted and characterized from three different parts (skin, scale, and bone) of bigeye tuna using the acid and pepsin extraction methods. The yield of acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) in skin were 13.5 ± 0.6% and 16.7 ± 0.7%, respectively, on a dry basis. The yields of PSC in scale and bone were 4.6 ± 0.3% and 2.6 ± 0.3%, respectively, while ASCs were in negligible amount. All the extracted collagens were type I collagen and a high level of imino acids (227–232/1000 residues) was found in all the extracted collagens. The thermal transition temperature (31.6–33.7 °C) and thermal denaturation temperature (31.1–32.2 °C) were higher than those of many temperate- and cold-water fish collagens. All collagens were highly soluble at acidic pH. The isoelectric points were 6.1, 6.4, 5.4, and 5.5 for skin-ASC, skin-PSC, scale-PSC, and bone-PSC, respectively. Therefore, the high collagen contents, especially in the skin, and higher thermal properties of the extracted collagens suggested that they have great potential for use as an alternate for mammalian collagen.

Capture-based tuna aquaculture rates as one of the most important aquaculture activities in Cro-atia, where juvenile tuna are reared in cages for over a year long period in order to increase substan-tially their weight. The aim of this study was to assess the effect of length and intensity of feeding on biochemical composition (total fat, moisture, dry matter, carbohydrates and protein content) of tuna (Thunnus thynnus) white muscle tissues in newly caught tuna prior to feeding (NCTPF) versus far-med tuna kept in rearing circular cages in the Vela Grska Bay, Adriatic Sea (LAT 43°17’40,6984”N, LONG 016°28’58,4315”E (WGS84)) between 2001 and 2004. Farmed tunas from all cages were fed with the feed consisting of domestic small pelagic fish, or with mixtures containing North Sea herring (Clupea harengus) and Sardina pilchardus, for five months (cage 3), eight months (cage 4) or 21 months (cages 1 and 2). A low content of moisture and high content of dry matter including fat was observed in farmed tuna muscles compared to wild-caught tuna. In farmed tuna muscles, measured moisture was 55.26% in cage 1, 39.95% in cage 2, 54.64% in cage 3 and 49.70% in cage 4. These results are significantly lower than moisture measured in NCTPF (80.36%). Content of dry matter found in farmed tuna muscles also differed greatly between wild tuna (19.64%) and far-med tuna, but also between the cages (44.74% in cage 1, 60.05% in cage 2, 45.36% in cage 3 and 50.30% in cage 4). In NCTPF, muscle tissues total fat encompassed less than 1% of the total body weight, while it reached over 20% of total body mass in farmed fed tuna (20.62% in cage 1, 42.50% in cage 2, 20.97% in cage 3 and 20.57% in cage 4). These results demonstrate that high fat content can be achieved already after five months of intensive feeding. Higher content of proteins was also found in aquacultured tuna (18.60% in cage 1, 16.00% in cage 2, 15.09% in cage 3 and 20.58% in cage 4) compared to wild-caught tuna (13.77%). There were no differences in carbohydrates con-tent between tuna farmed in different cages and NCTPF tuna, indicating glycogen as a less optimal indicator of muscle tissue quality in farmed tuna of the present study., Kavezni uzgoj tune uhvaćene u divljini, tijekom razdoblja dužeg od jedne godine, sve dok tuna ne dobije znatno na težini, jedan je od najznačajnijih akvakulturnih aktivnost u Hrvatskoj. Cilj ovog rada je odrediti utjecaj intenziteta i duljine ishrane na biokemijski sastav bijelog mišićnog tkiva (uku-pni sadržaj masti, vode, suhe tvari, ugljikohidrata i proteina) tek ulovljene tune (Thunnus thynnus) prije tovljenja, u odnosu na tunu uzgajanu u kavezima kružnog oblika između 2001. i 2004. u uvali Vela Grška, koja se nalazi na južnoj obali otoka Brača u hrvatskom dijelu Jadranskog mora (LAT 43°17’40,6984”N, LONG 016°28’58,4315”E (WGS84)). Tuna uzgajana u sva četiri kaveza hranje-na je domaćom malom plavom ribom ili mješavinom haringe iz Sjevernog mora (Clupea harengus) i srdele (Sardina pilchardus), i to tijekom pet mjeseci (kavez 3), osam mjeseci (kavez 4) odnosno 21 mjesec (kavezi 1 i 2). Niski udjeli vode i visoki udjeli suhe tvari, uključujući masti, zabilježeni su u mišićnom tkivu uzgajane tune u odnosu na divlju tunu. U mišićnom tkivu kavezno uzgajane tune zabilježeno je 55.26% vode u kavezu 1, 39.95% u kavezu 2, 54.64% u kavezu 3 i 49.70% u kavezu 4, što su značajno niže vrijednosti od vrijednosti izmjerenih za divlju tunu (80.36%). Udio suhe tvari u mišićnom tkivu uzgajane tovljene tune značajno se razlikovao od udjela suhe tvari nađene u mišićnom tkivu divlje tune (19.64%), ali u mišićnom tkivu tuna uzgajanih u različitim kavezima (44.74% u kavezu 1, 60.05% u kavezu 2, 45.36% u kavezu 3 i 50.30% u kavezu 4). Ukupne masti u mišićnom tkivu čine manje od 1% ukupne težine tijela divlje tune, dok su te vrijednosti u tovljenih tuna: 20.62% u kavezu 1, 42.50% u kavezu 2, 20.97% u kavezu 3 i 20.57% u kavezu 4. Ovi rezultati upućuju na to da se visok sadržaj masti može postići već nakon pet mjeseci intenzivnog tovljenja tune. Visoke vrijednosti udjela proteina nađene su u mišićnom tkivu uzgajanih tuna (18.60% u kavezu 1, 16.00% u kavezu 2, 15.09% u kavezu 3 i 20.58% u kavezu 4) u usporedbi s mišićnim tkivom divlje tune (13.77%).Udio ugljikohidrata u mišićnom tkivu tuna nije se značajno razlikovao između tuna uzgajanih u različitim kavezima (0.83% u kavezu 1, 0.57% u kavezu 2.0 66% u kavezu 3 i 0.37 u kavezu 4), kao ni u usporedbi s mišićnim tkivom divljih tuna (0.31%). Kako ugljikohidrati potječu iz glikogena koji se brzo sintetizira i razgrađuje, sadržaj glikogena u mišićnom tkivu tune, manje je pogodan param-etar za ocjenu kvalitete mišićnog tkiva uzgajane ribe.

The objective of this study was to investigate water dynamics and protein changes in bigeye tuna (Thunnus obesus) stored at 0 °C and 4 °C for up to 6 days. The values of various protein parameters (trichloroacetic acid (TCA)-soluble peptide content, Ca2+-ATPase enzyme activity and total -SH content) decreased with increasing storage time. Fourier transform infrared spectra indicated that the secondary structure of the proteins changed; the contents of α-helixes and β-turns significantly decreased, while that of β-sheets significantly increased (p

The length and weight of Thunnus albacares (Bonnaterre, 1788) off north Andhra Pradesh during 2012 - 2015 were studied and the length-weight relationship was found out. A total of 3,617 specimens were analysed and the reported length range was18 cm to 186 cm fork length. In the fishery, peak landings of size classes 41-50 cm and 111-120 cm were observed. Annual mean lengths ranged from 62.7 cm to 92.7 cm. The highest mean length of 92.7 cm was recorded in 2014 and the lowest mean length of 62.7 cm was recorded in 2015. Length-weight relationship was not found to differ significantly between sexes and the pooled relation was log W = log 0.016 + 2.996 log L. The growth pattern observed was isometric.

The purpose of this study, to determine the effect of temperatura on embryonic development and early stadia larvae of yellow fin tuna (Thunnus albacares) and the level abnormalities of the larvae. This research was carried out in a Large Marine Aquaculture Center And Hyacinth Fisheries Gondol. The container used is a 1 liter backer glass of 15 pieces. Egg density at each backer glass is 300 grains. The temperature treatment used is (240C±1), P2 (260C±1), P3 (280C±1), P4 (300C±1), P5 (320C±1). Parameters observed were egg hatchability, egg hatching time, larval abnormalities, absorption of egg yolk and larval length. Based on the result of the study showed that different temperature treatments were able to give a significant influence on the development of eggs and the time of hatching egg. The temperature treatment 260C was able to increase the hatchbility value by 40,7%, larvae abnormality value 15,8%, larvae length growth 5,48 mm compared to other temperature treatment. The best egg yolk absorption rate is shown at the temperature treatment of 240C, 260C, and 280C compared to the 300C and 320C temperature treatments.

We examined Southern bluefin tuna, Thunnus maccoyii, larvae to identify specific retinal adaptations that would indicate both important parameters for culture and larval ecology in the wild. Plastic resin histology, microspectrophotometry and behavioural feeding responses were used to describe visual development. Thunnus maccoyii larvae reflected the visual morphogenesis template commonly observed in many other marine fish species exhibiting indirect development. First-feeding (3 days post-hatching, [dph], 3.4 mm standard length [SL]) larvae possessed tightly packed single cone photoreceptors. Rods and twin cones were present in the retina in post-flexion larvae (21 dph, 8.39 mm fork length [FL]) with cone mosaic patterns observed in juveniles (30 dph, 21 mm FL). Based on the spacing of adjacent photoreceptors and focal length, first feeding larvae had a maximum theoretical visual acuity of 1.23 ± 0.11° that decreased to 0.14 ± 0.02° at 30 dph. Thunnus maccoyii displayed high cell density in the ventral retinal region (cones, bipolar and horizontal cells), a low convergence of cone cells to ganglion cells throughout the retina during larval development (1.1 ± 0.2 to 1.4 ± 0.3 at 3 dph and 30 dph, respectively), and early development of retinal pigment epithelium (RPE) migration. Microspectrophotometry showed twin cone visual pigments maximally sensitive to light in the blue-green part of the visual spectrum (wavelength of maximum absorption [λmax] of 494 nm, 507 nm and 524 nm), and behavioural experiments showed they fed preferentially at these wavelengths. Increased retinal cone densities in the ventral region indicated a localized region specialized for acute vision for prey and predator detection in the upward direction (dorsal plane) at an early age, representing a possible adaptation to life in deeper oceanic waters. The apparent high acuity and photopic sensitivity observed in T. maccoyii is hypothesised to be associated with the ability to feed in low light conditions. This has important practical considerations in determining lighting regimes for culture of T. maccoyii and possibly for other tuna species.

Tuna species are a popular food among consumers. They are mostly sold as heat-processed canned products on the market. Different quality and price of tuna species can lead the producer to the adulteration of food products. The main difficulties in developing a method for species identification in these fish is the high similarity of DNA sequences among close relative fish species. All complete mitochondrial DNA sequences of skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) were compared to all other mitochondrial DNA sequences of tuna fish deposited in the GenBank. The most variable regions within species were determined and primers and probes were designed in this region for the species-specific DNA amplification of skipjack tuna and yellowfin tuna. Moreover, to check the content of amplifiable DNA of fish (namely tuna) in the sample, primers and a probe of mitochondrial12SrRNAgene in the region of conservative sequence were designed. Real time PCR methods were verified by investigating 51 samples of canned tuna with the declared content of tuna species from the market; the species was confirmed in all tested samples. This method was designed to be suitable for the determination of DNA sequences especially in highly heat treated products.

Analysis on the catch of Bigeye tuna (Thunnus obesus) from purse seine and ring nets of various net depths was conducted to assess the effect of reducing net depth as a compatible measure the Philippines has implemented and reducing the catch of Bigeye in its internal waters and the Exclusive Economic Zone (EEZ). The study was based on observer reports from ring net and purse seine fishing vessels operating in internal waters and EEZ as well as from group seine operations in the high seas pocket 1. Nets were classed by depth to determine and compare variations on the catch of Bigeye, catch rates and relative proportion, species composition, and fishing grounds. Results indicated that the catch of Bigeye is correlated with the depth of net, with a significantly higher catch of Bigeye in deeper nets. The result of the study is consistent with other studies elsewhere, and in consonance with the implementation of Fisheries Administrative Order 236 limiting the depth to 115 fathoms for ring net and purse seine operating in Philippine internal waters and the EEZ as a compatible measure to reduce the catch of Bigeye.

In this study, the authors examined late atretic follicles in the ovaries of Atlantic bluefin tuna, Thunnus thynnus (Linn AE us 1758), at different times of the year using transmitted light and epifluorescence microscopy. Atresia (degeneration and resorption of developing ovarian follicles) is a natural process involved in fecundity downregulation in teleosts and is substantially enhanced in stressful conditions. Early (alpha and beta) atretic stages of yolked oocytes have a relatively short duration in seasonally reproducing species, whereas later (gamma and delta) atretic follicles (LAF) persist for longer time in the ovary, serving as a sign of previous vitellogenic activity. LAF can thus be used as reliable markers of maturity during non-reproductive periods. Lipofuscin granules accumulate in the cytoplasm of LAF cells as a result of lysosomal digestion of oocyte components. Taking advantage of the well-known autofluorescent properties of lipofuscins, LAF may be identified in unstained histological sections under fluorescence microscopy using appropriate excitation and emission wavelengths. The authors explore in this study the applicability of fluorescence microscopy to provide a fast and effective method to assess late atresia in fishes. This method may be particularly useful to determine sexual maturity in individuals sampled long after the spawning season, where LAF are difficult to detect in standard histological sections. Furthermore, LAF autofluorescence provides a rapid way to quantify late atresia in fishes using image analysis., This research was partly funded by the CEI MAR Foundation (project #CEIJ19-C02.1), the Spanish Ministry of Economy and Competitiveness (project #CTM2017-82808-R) and the Andalusian Government (P12-RNM733, FEDER UCA18-107069).

One of the most promising aquaculture species is the Atlantic bluefin tuna ( Thunnus thynnus ) with high market value; disease control is crucial to prevent and reduce mortality and monetary losses. Microsporidia Balbiani, 1882 (Fungi) are a potential source of damage to bluefin tuna aquaculture. A new microsporidian species is described from farmed bluefin tunas from the Spanish Mediterranean. This new pathogen is described in a juvenile associated with a highly severe pathology of the visceral cavity. Whitish xenomes from this microsporidian species were mostly located at the caecal mass and ranged from 0.2 to 7.5 mm. Light and transmission electron microscopy of the spores revealed mature spores with an average size of 2.2 × 3.9 μm in size and a polar filament with 13–14 coils arranged in one single layer. Phylogenetic analysis clustered this species with the Glugea spp. clade. The morphological characteristics and molecular comparison confirm that this is a novel microsporidian species, Glugea thunni sp. nov. The direct life cycle and the severe pathologies observed makes this parasite a hard risk for bluefin tuna cultures.

Thunnus atlanticus es de gran importancia comercial en Brasil, pero las infecciones causadas por helmintos parásitos puede reducir su valor comercial. En este trabajo, 15 especies de Digenea y tres de Monogenoidea fueron recuperados de 61 ejemplares de T. atlanticus recogidos de la zona costera del Estado de Río de Janeiro. Las especies de la familia Didymozoidae eran las especies dominantes, con mayores valores de prevalencia y de abundancia. Los parásitos mostraron el patrón de distribución agregado típico, excepto para Nasicola brasiliensis, que tenía un patrón de distribución aleatoria. La prevalencia y abundancia de Didymosulcus philobranchiarca, Didymocystis lamotheargumedoi y Didymosulcus wedli y la prevalencia de Koellikerioides internogastricus se correlacionaron positivamente con la longitud total del hospedador. La abundancia de Coeliotrema thynni se correlacionó negativamente con la longitud total del hospedador. Nuevos registros de hospedadores resultaron para cuatro especies de Digenea: Didymosulcus orbitalis, Didymosulcus wedli, Rhipidocotyle pentagonum y Lecithochirium microstomum, y uno Monogenoidea: Nasicola brasiliensis.

Bigeye tuna (Thunnus obesus, Lowe, 1839) is one of the eight recognized species of the genus Thunnus. It is considered a tropical species distributed in the Atlantic, Pacific and Indian Oceans. To date, no validated presence of this species has been reported inside the Mediterranean Sea. This study, however, confirms, for the first time, the presence of three young individuals of this species within the Mediterranean Sea Open Access funding provided thanks to the CRUE-CSIC agreement with Wiley

Yellowfin tuna Thunnus albacares is a highly exploited species in the Indian Ocean. Yet, its stock structure is still not well understood, hindering assessment of the stock at a suitable spatial scale for management. Here, young-of-the-year (13C and δ18O). Significant regional variation in otolith chemical signatures was detected among nurseries, except between Madagascar and Seychelles-Somalia. Otolith δ13C and δ18O were important drivers of differentiation between western (Madagascar and Seychelles-Somalia), Maldives and Sumatra nurseries, whereas the elemental signatures were cohort specific. Overall nursery assignment accuracies were 69-71%. The present study demonstrates that baseline chemical signatures in the otoliths of yellowfin tuna are regionally distinct and can be used as a natural tag to investigate the nursery origin of older individuals in the Indian Ocean.