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The family Scombridae, comprising of commercially important marine fishes, which are widely distributed across tropical, subtropical, and temperate waters. Scombrids constitute an important fishery and are exploited across their range of distribution. Accurate identification of species is important for effective fisheries management and forensics purposes. In the present study, commercially important species of scombrids distributed in Indian waters were selected for molecular phylogeny and development of species-specific diagnostic keys using mitochondrial cytochrome c oxidase I (COI) gene. In addition to morphological identification, the species were identified using molecular-based identification approach and character-based identification system. Molecular phylogeny for 16 species of scombrids was ascertained using mitochondrial COI analyses. The character-based molecular diagnostic keys for 16 species of scombrids were developed in-silico from data set comprising 603 mtCOI sequences generated in the present study as well as collected from published resources. The study uncovered 39 unambiguous molecular keys, capable of distinguishing all reference taxa under study. The development of species-specific sequences and key diagnostic nucleotides for scombrid fish species will be helpful in effective forensic applications, enforcement of fisheries regulations, and for sustainable utilization of this commercially important group of species.

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.

Purpose: Describe a new species of didymozoid digenean Neonematobothrium Yamaguti, 1965 from the operculum of the scombrid fish, Euthynnus alletteratus (Rafinesque, 1810), in the Southwest Atlantic Ocean off Brazil. Methods: Thirty-four specimens of E. alletteratus were collected in the coastal zone of the state of Rio de Janeiro and obtained from local fishermen between 2006 and 2018 in the municipal market of São Pedro in Niterói, Brazil. The parasites were fixed in AFA (93% ethanol 70%, 5% formaldehyde, 2% glacial acetic acid) without pressure, stained with Langeron alcoholic acid carmine, dehydrated in an alcohol series, cleared in beachwood creosote or clove oil and mounted in Canada balsam as permanent slides. Results: Neonematobothrium annakohnae n. sp. is a member of the genus based on a combination of the following characteristics: body free, uncapsulated; body long and dorsoventrally flattened; esophagus surrounded by gland cells; ovary and vitellarium single, long, narrow and unbranched in the anterior and posterior halves of the body, respectively; uterus with three loops; and site of infection in subcutaneous tissue of scombrid fish. The new species differs from the two recognized species of the genus mainly by the size of the body, which is much larger, the shape of the genital pore, which is differentiated in a structure similar to a small sucker and by esophagus without diverticula. Conclusions: Neonematobothrium annakohnae n. sp. parasite of E. alletteratus from the Southwest Atlantic Ocean, described herein, represents the third species of Didymozoidae belonging to the genus Neonematobothrium. The two known species Neonematobothrium kawakawa Yamaguti, 1965 and Neonematobothrium dorsale Yamaguti, 1970 were described from fish belonging to the same genus of the host from Pacific Ocean. The diagnosis of the genus is enlarged to "esophagus with or without diverticula", to fill the characteristics presented by the new species. The description of N. annakohnae n. sp. demonstrates the need to expand the studies of these interesting and intriguing group of parasites, due to the fact that number of known didymozoids taxa in the Atlantic Ocean is far from representing the real situation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Large scombrids, commercial tuna species, are regularly assessed and managed. However, most of the small scombrids, many mackerels and bonitos, lack accurate catch data to implement traditional stock assessments despite their economic importance in many small-scale fisheries. In this study, we analysed different approaches using length composition data from multiple fleets with different gear selectivity to assess small scombrids in the Atlantic Ocean. Using simulated populations, we compared two length-based methods (length-based spawning potential ratio and length-based integrated mixed effects), under different length data grouping scenarios. We found that using length data from the fleet targeting the broadest range of sizes resulted in the lowest bias in spawning potential ratio of all options tested. Based on these results, we used biological and length data to estimate a quantitative proxy of current stock status for ten small scombrid stocks in the Atlantic Ocean. We found that some stocks are likely to be overfished, such as little tunny (Euthynnus alletteratus) in the Southeast Atlantic and wahoo (Acanthocybium solandri) in the Northwest Atlantic. This is a starting point in the estimation of stock status for these species, but should not be thought of as a replacement for other more data-intensive assessments. [ABSTRACT FROM AUTHOR]

In this study, we first identify seven criteria for the design of biomimetic robotic fish and focus on two of these tasks: shape and hydromechanics. For this purpose, fish body part measurements were obtained using previous work and also captured and harvested fish samples to construct computer-aided design (CAD) models of three fish species: Scomber scombrus , Sarda sarda , and Thunnus thynnus. Dead body drag and caudal fin flapping were considered as two separate problems. Computational simulations were carried out to determine drag and propulsive performance. Body drag simulations showed that the Reynolds dependence of the drag coefficient of three different species can be adequately expressed by a single laminar scaling correlation. At the same length and swimming speed, the Atlantic mackerel experiences the least drag. Caudal fin deformation simulations showed that the Atlantic bluefin tuna offers the highest thrust and efficiency. Peak efficiency is in the range of 31–35 percent observed at the same optimal Strouhal number, St = 0.5, for all species. It is shown that the aspect ratio as the main length scale influences propulsion performance. • CAD models of three fish species (Scomber scombrus , Sarda sarda , and Thunnus thynnus) were reconstructed from length measurements. • Reynolds dependence of the drag coefficient of three different species can be adequately expressed by a single scaling correlation. • At the same length and swimming speed, the Atlantic mackerel experiences the least drag. • Atlantic bluefin tuna offers the highest thrust and efficiency. • Peak efficiency is in the range of 31–35 percent observed at the same optimal Strouhal number. [ABSTRACT FROM AUTHOR]

The relationship between the biomass of reproductively mature individuals (spawning stock) and the resulting offspring added to the population (recruitment), the stock–recruitment relationship, is a fundamental and challenging problem in all of population biology. The steepness of this relationship is commonly defined as the fraction of recruitment from an unfished population obtained when the spawning stock biomass is 20% of its unfished level. Since its introduction about 20 years ago, steepness has become widely used in fishery management, where it is usually treated as a statistical quantity. Here, we investigate the reproductive ecology of steepness, using both unstructured and age-structured models. We show that if one has sufficient information to construct a density-independent population model (maximum per capita productivity and natural mortality for the unstructured case or maximum per capita productivity, natural mortality and schedules of size and maturity at age for the structured model) then one can construct a point estimate for steepness. Thus, steepness cannot be chosen arbitrarily. If one assumes that the survival of recruited individuals fluctuates within populations, it is possible, by considering the early life history, to construct a prior distribution for steepness from this same demographic information. We develop the ideas for both compensatory (Beverton–Holt) and over-compensatory (Ricker) stock–recruitment relationships. We illustrate our ideas with an example concerning bluefin tuna ( Thunnus thynnus/orientalis, Scombridae). We show that assuming that steepness is unity when recruitment is considered to be environmentally driven is not biologically consistent, is inconsistent with a precautionary approach, and leads to the wrong scientific inference (which also applies for assigning steepness any other single value). [ABSTRACT FROM AUTHOR]

Abstract: In the present work, a method for the authentication of scombroid products was developed, by means of FINS (Forensically Informative Nucleotide Sequencing) technique (Polymerase Chain Reaction (PCR) followed by phylogenetic analysis). The methodology developed allows the identification of most important scombroid species using the mitochondrial cytochrome b as molecular marker. Due to the different commercial value of the species belonging to this family, substitutions between species in seafood products can take place. Several methodological strategies allow the authentication of scombroid species in all kind of products, from fresh fish to canned products, the more usual format for marketing such species. This analytical system was validated and subsequently applied to 20 commercial samples labelled as tuna, bonito, mackerel and frigate tuna, obtaining three that were incorrectly labelled (15%). Therefore, this technique can be used as a routine method to avoid the mislabelling in the marketing of scombroid species and it is also suitable to assess the correct seafood traceability of these products. [Copyright &y& Elsevier]

Aquaculture is providing an ever-increasing proportion of fish in the human food basket, prompting a search for new species to expand the range available to consumers. Large tunids/scombrids have long since been a very valuable resource, providing not only high-quality protein but also a rich source of the highly beneficial omega-3 (or n-3) long-chain polyunsaturated fatty acids, including eicosapentaenoic and, especially, docosahexaenoic acids in the human diet. Consequently, there is considerable interest worldwide in developing the culture of large tunids, including Atlantic northern bluefin tuna (Thunnus thynnus), Pacific bluefin tuna (Thunnus orientalis), southern bluefin tuna (Thunnus maccoyii), and yellowfin tuna (Thunnus albacares). Nutrition is vital to this development, playing key roles in reproductive success, including the establishment of successful broodstock producing high-quality eggs and larvae and, ultimately, the cost-effective production of nutritious seafood. This review summarizes the rather fragmentary data that compromise the current state of the art in relation to tuna nutrition and the development of artificial, formulated feeds for these species. In highlighting the various considerable challenges that feed development will pose, we discuss the future perspectives for tuna culture in terms of both fish and human nutrition and welfare against the background of diminishing global marine resources. [ABSTRACT FROM AUTHOR]

Collagen peptide mass fingerprinting of archaeofaunal remains, or Zooarchaeology by Mass Spectrometry (ZooMS), has increasingly established itself as a valuable tool for improving our understanding of highly-fragmented faunal assemblages. Although there have been developments in sampling strategies that have attempted to reduce damage to precious archaeological specimens, these tend to yield spectra inferior in quality to those yielded by destructive approaches. Also, in an effort to mitigate the impacts on faunal assemblages, researchers are beginning to turn to microCT for the digital preservation of specimens, as this enhances their value for further studies. Here we combine ZooMS and microCT, in application to over one hundred scombrid remains from the Hanamiai site in the Marquesas, which spans the time period from initial human colonization by Polynesians at ca. AD 1250 until around 1900. Almost all of the hypurals that yielded collagen fingerprints (71 of 73) were confirmed as skipjack. The results suggest striking continuity over time in fishing practices with an inferred emphasis on fishing strategies involving sailing canoes being present from the time of initial settlement. The focus appears to be on daytime fishing for skipjack rather than on night fishing for yellowfin, kawakawa and dogtooth tuna as might otherwise have been expected. • First use of high-throughput microCT scanning for archaeological bone. • Identification of new species biomarkers for scombrids. • Discovered continuity over time in fishing practices with emphasis on strategies involving sailing canoes. [ABSTRACT FROM AUTHOR]

Striped bonito Sarda orientalis larvae and juveniles were reared in a laboratory from hatching to 14 days post hatching, and the development of their digestive system was investigated histologically. On day 2 (first feeding day), the larval-type digestive system was differentiated. On day 3, a blind sac with densely distributed gastric glands developed and pyloric ceca appeared, suggesting that the digestive system was attaining adult-type structure. The yolk was completely absorbed on day 4. Bonito larvae preyed on rotifers and/or Artemia nauplii on day 2, but almost the whole gut was occupied by fish larvae from day 4. In the striped bonito, the adult-type digestive system was established right after first feeding, and this precocious development was well synchronized with the appearance of piscivory. [ABSTRACT FROM AUTHOR]

Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (δ 15 N) are primarily used to estimate trophic position while carbon isotopes (δ 13 C) describe habitat associations and feeding pathways. Models of both δ 15 N and δ 13 C values and their associated variance can be used to estimate likely dietary contributions and niche width and provide inferences about consumer movement and migration. Stable isotope data have added utility when used in combination with other empirical data sets (e.g., stomach content, movement tracking, bioregionalization, contaminant, or fisheries data) and are increasingly relied upon in food web and ecosystem models. While numerous regional studies publish tables of mean δ 15 N and δ 13 C values, limited individual records have been made available for wider use. Such a deficiency has impeded full utility of the data, which otherwise would facilitate identification of macroscale patterns. The data provided here consist of 4,498 records of individuals of three tuna species, Thunnus alalunga, T. obesus, and T. albacares sampled from all major ocean basins from 2000 to 2015. For each individual tuna, we provide a record of the following: species name, sampling date, sampling location, tuna length, muscle bulk and baseline corrected δ 15 N values, and muscle bulk and, where available, lipid corrected δ 13 C values. We provide these individual records to support comparative studies and more robust modeling projects seeking to improve understanding of complex marine ecosystem dynamics and their responses to a changing environment. There are no copyright restrictions for research and/or teaching purposes. Users are requested to acknowledge their use of the data in publications, research proposals, websites, and other outlets following the citation instructions in Class III, Section B., (© 2020 The Authors. Ecology © 2020 The Ecological Society of America.)

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 ., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The scombrids (Family Scombridae), commonly known as tunas, bonitos, Spanish mackerels, and mackerels, play an important role as predators and prey in coastal and oceanic marine ecosystems, and sustain some of the most important fisheries in the world. Knowledge of their basic biology and life history traits, such as growth, age, and maturity, is fundamental to sustainably manage these species, and maintain their critical role in marine ecosystems. Given the economic and social importance of their fisheries in many regions throughout the world, numerous life history studies have been conducted in the last century. Despite efforts to create global repositories of life history parameters, e.g., FishBase, many life history studies remain scattered and not readily accessible. Here, we compiled 667 life history studies published between 1933 and 2012 describing the growth, age, and reproductive biology of the 51 species of scombrids distributed around the world and create a standardized life history data set including maximum size, longevity, growth, maturity, fecundity, spawning season and frequency, and egg size information. We created this data set to promote the best use of the existing life history information and with the intention of providing a data resource suitable to test large-scale ecological hypotheses on life history strategies and life history evolution, as well as support the management and conservation of this important group of commercially exploited species. We envisage the large repository of standardized life history data compiled will make this endeavor more effective and robust by providing a valuable resource that can help address many research questions. [ABSTRACT FROM AUTHOR]

Larger-bodied species in a wide range of taxonomic groups including mammals, fishes and birds tend to decline more steeply and are at greater risk of extinction. Yet, the diversity in life histories is governed not only by body size, but also by time-related traits. A key question is whether this size-dependency of vulnerability also holds, not just locally, but globally across a wider range of environments. We test the relative importance of size- and time-related life-history traits and fishing mortality in determining population declines and current exploitation status in tunas and their relatives. We use high-quality datasets of half a century of population trajectories combined with population-level fishing mortalities and life-history traits. Time-related traits (e.g. growth rate), rather than size-related traits (e.g. maximum size), better explain the extent and rate of declines and current exploitation status across tuna assemblages, after controlling for fishing mortality. Consequently, there is strong geographical patterning in population declines, such that populations with slower life histories (found at higher cooler latitudes) have declined most and more steeply and have a higher probability of being overfished than populations with faster life histories (found at tropical latitudes). Hence, the strong, temperature-driven, latitudinal gradients in life-history traits may underlie the global patterning of population declines, fisheries collapses and local extinctions. [ABSTRACT FROM AUTHOR]