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The genetic diversity of the Mediterranean swordfish (Xiphias gladius Linneus) has not been explored extensively at its easternmost range so far. In this study, modern X. gladius samples from the eastern part of the Mediterranean basin, north of the Aegean Sea (Aegean-2013, n = 26) and the Mediterranean coast of Turkey (N.Levantine-2013, n = 42) were studied genetically, along with ancient samples from Yenikapi excavation (n = 6). Partial mitochondrial DNA control region sequences (entire sequences, clade I and clade II) were evaluated spatially and temporally together with previously published sequences (Alvarado Bremer et al., Molecular Phylogenetics and Evolution, 2005, 36, 169-187; Vinas et al., ICES Journal of Marine Science, 2010, 67, 1222-1229; Righi et al., Diversity, 2020, 12, 170) from the rest of the Mediterranean Sea. Pair-wise FST and pair-wise AMOVA tests showed that, in general, groups of eastern populations and western Mediterranean populations have not genetically differed from each other significantly nearly in the past 20 years. Therefore, the results direct reconsideration of previous descriptions of population sub-structure within the Mediterranean and support high gene flow throughout the region. On the contrary, the results of this study confirmed the existence of genetic diversity differences between western and eastern Mediterranean, with eastern being low. One-tailed permutation tests revealed that θ, which is directly proportional to long-term female effective population size (Ne), decreased significantly (P

The common dolphinfish (Coryphaena hippurus) is an epipelagic, mid-trophic level, highly migratory species distributed throughout the world’s tropical and subtropical oceans in waters greater than 20°C. Life-history variables, migratory behaviour, and genetic markers have been used to define major stocks in the central Atlantic Ocean and Mediterranean Sea. Here, we used the mitochondrial DNA gene NADH subunit 1 (688 bp) to test for differences between population groups. A total of 103 haplotypes were detected among 203 fish. Gene diversities in samples were large and similar among populations (mean h = 0.932; range 0.894–0.987), but nucleotide diversities varied widely among samples (range π = 0.004–0.034) and appear to reflect population histories. Principal component analysis revealed two large populations groups, and the analysis of molecular variation and pairwise values of ΦST resolved population structure within these groups. Populations in the eastern Atlantic and Mediterranean showed the largest amounts of divergence from one another (ΦCT = 0.331). Adult movement and biophysical barriers to larval dispersal may explain contemporary differences between stocks, but the divergent populations in the Mediterranean Sea are likely due to isolations by cold temperature barriers during Pleistocene glaciations. The geographically large stock groupings require international cooperation in the harvest management and conservation of local dolphinfish populations.

In this review, the mechanism of action of poisons and toxic effects of and treatment methods for the same among weever fishes, which are present along the coast of Turkey, were addressed. Weever fish poison is present in the spicule located on the operculum and in the 5th-8th dorsal spines located on the first dorsal fin. Weever fish poisoning is identified through symptoms of intense pain, burning, and stinging. The duration of these symptoms varies among patients and depends on the species and season. Contrary to common belief, instead of immersion in cold water, immersion in hot water at about ≥40°C is used during emergencies., Bu derleme çalışmasında ülkemiz kıyılarında dağılım gösteren trakonya balıklarının zehir ve toksik etki mekanizmaları ile tedavi yolları irdelenmiştir. Trakonya zehri, solungaç kapağı üzerinde bulunan operküler dikende ve 1.dorsal yüzgeçte bulunan 5-8 dorsal dikende bulunur. Trakonya zehirlenmeleri ani bir ağrı, yanma ve iğneleme şeklinde ortaya çıkmaktadır. Bu bulguların süresi hastaya, balığın cinsine ve mevsimlere göre değişmektedir. Halk arasında bilinenin aksine acil servis müdahalesi olarak soğuk su yerine etkilenen bölgenin 60-90 dakika yaklaşık 40oC veya daha sıcak suya daldırılması gerekmektedir.

Available knowledge on the assemblage patterns of demersal macro-faunal species in the Black Sea is scarce. For this reason, data series of demersal trawl surveys between 2011 and 2014 were collected to identify the demersal assemblages along the continental shelf in the southwestern Black Sea. Data were analysed from 146 demersal trawl hauls conducted in the spring and autumn periods for three bathymetric contours: 0–20 m, 20–50 m, and 50–100m. The spatial and temporal structural patterns of demersal zonation were assessed using multivariate analyses. Out of a total of 78 taxa, 69 demersal species were identified. Fishes showed the highest diversity with 41 species followed by 16 mollusks, 11 crustaceans, 5 echinoderms, 1 tunicate, and 1 porifera. Multivariate analyses revealed significant differences in the assemblages according to depth, sub-region, season, and year. Statistically, depth was the most influential factor determining the ordination of the faunal zonation. This study concludes that Merlangius merlangus, Mullus barbatus, Mytilus galloprovincialis, and Liocarcinus depurator may be the indicator species that make the greatest contribution to the formation of the demersal macro-community.

In this study, the stomach contents of 116 albacore specimens, Thunnus alalunga were examined from the eastern Mediterranean Sea. Fifty-five of the 116 stomachs examined were empty. The occurrence of major prey categories in stomachs were 95.1% cephalopods, 47.5% teleosts and 39.3% crustaceans with a total of 633 individuals belonging to 14 species identified. Heteroteuthis dispar from the order Sepiolida constituted 56.40% of the main cephalopod prey followed by Onychoteuthis banksii from the order Teuthida.

Data on technical specifications, numbers, catch, fishing power per boat and CPUE of purse-seining boats for the tuna fishery in the Turkish waters between 1994 and 2000 periods are presented. The number of the purse-seining boats operating during the period varied between 22 and 62. In recent years, the bluefin fishing fleet and the fishery have been transformed. The fleet now consists of larger boats with more powerful engines, bigger fishing nets, and the use of sophisticated electronics like echosounders, sonars and sea bird radars. Those factors combined with the increased captain’s experience and skill in using the technologies are important factors that have resulted in significant changes in the traditional measures of effectiveness of the Turkish tuna fishery.

Assessment and management of Atlantic bluefin tuna Thunnus thynnus populations is hindered by our lack of knowledge regarding trans-Atlantic movement and connectivity of east- ern and western populations. Here, we evaluated migratory and homing behaviors of bluefin tuna in several regions of the North Atlantic Ocean and Mediterranean Sea using chemical tags ( δ 13 C and δ 18 O) in otoliths. Significant emigration of bluefin tuna from their place of origin was inferred from otolith δ 13 C and δ 18 O, with both eastern and western bluefin tuna commonly ‘crossing the line’ (45° W management boundary) in the Central North Atlantic Ocean and mixing with the other population. Several western migrants were also detected in Moroccan traps off the coast of Africa, indicating that trans-Atlantic movement occurs for members of the western population; however, the degree of mixing declined with proximity to the eastern spawning area (Mediterran- ean Sea). The origin of bluefin tuna collected at the entrance to the Strait of Gibraltar and from several regions within the Mediterranean Sea (Balearic Islands, Malta, and Sardinia) was essen- tially 100% eastern fish, demonstrating that natal homing is well developed by the eastern popu- lation, with western migrants rarely entering the Mediterranean Sea., SI

Two stocks of bluefin tuna (Thunnus thynnus) inhabit the north Atlantic; the western and eastern stocks spawn in the Gulf of Mexico and the Mediterranean Sea respectively. Trans-Atlantic movements occur outside spawning time whereas natal homing maintains stock structure. Commercial fisheries may exploit a mixed assemblage of both stocks. The incorporation of mixing rates into stock assessment is precluded by uncertainties surrounding stock discrimination. Otolith shape descriptors were used to characterise western and eastern stocks of Atlantic bluefin tuna in the present study and to estimate stock composition in catches of unknown origin. Otolith shape varied with length and between locations and years. Within a restricted size range (200–297-cm fork length (FL)) the two stocks were distinguished with an accuracy of 83%. Bayesian stock mixture analysis indicated that samples from the east Atlantic and Mediterranean were predominantly of eastern origin. The proportion assigned to the eastern stock showed slight spatial variation; however, overlapping 95% credible intervals indicated no significant difference (200–297cm FL: central Atlantic, 73–100%; Straits of Gibraltar, 73–100%; Morocco, 50–99%; Portugal 64–100%). Otolith shape could be used in combination with other population markers to improve the accuracy of mixing rate estimates for Atlantic bluefin tuna.

Fishing trials were carried out with gill nets and trammel nets in the northern Aegean Sea from March 2004 to February 2005. Four different mesh sizes for the gill nets and the inner panel of trammel nets (16, 18, 20 and 22 mm bar length) were used. Selectivity parameters for the five most economically important species, bogue (Boops boops), annular sea bream (Diplodus annularis), striped red mullet (Mullus surmuletus), axillary sea bream (Pagellus acarne) and blotched picarel (Spicara maena), caught by the two gears were estimated. The SELECT method was used to estimate the selectivity parameters of a variety of models. Catch composition and catch proportion of several species were different in gill and trammel nets. The length frequency distributions of the species caught by the two gears were significantly different. The bi-modal model selectivity curve gave the best fit for gill net and trammel net data, and there was little difference between the modal lengths of these nets. However, a clear difference was found in catching efficiency. The highest catch rates were obtained with the trammel net. Given that many discard species and small fish are caught by gill nets and trammel nets with a mesh size of 16 mm, it is clear that these nets are not appropriate for fisheries. Consequently, the best mesh size for multispecies fisheries is 18 mm. This mesh size will considerably reduce the numbers of small sized individuals and discard species in the catch., Se realizaron ensayos de pesca con betas y trasmallos en el Egeo septentrional desde marzo de 2004 a febrero de 2005. Se utilizaron cuatro luces de malla distintas (16, 18, 20 y 22 mm) tanto para las betas como para el paño interno de los trasmallos. Se estimaron los parámetros de selectividad de las cinco especies más importantes capturadas por ambos artes: boga (Boops boops), raspallón (Diplodus annularis), salmonete de roca (Mullus surmuletus), aligote (Pagellus acarne) y chucla (Spicara maena). Se utilizó el método SELECT para la estimación de los parámetros de selectividad de varios modelos. La composición en tallas de la captura así como la proporción de las distintas especies capturadas por las betas y trasmallos fueron diferentes. La distribución de frecuencias de tallas de las especies capturadas por ambos artes fueron significativamente diferentes. El modelo de curva de selectividad bimodal fue el que mejor se ajustó a los datos de betas y trasmallos, y se encontraron muy pocas diferencias entre las longitudes modales de ambos artes. No obstante, se encontró una diferencia clara en la eficiencia de captura. Las tasas de captura más altas correspondieron a los trasmallos. Teniendo en cuenta que con betas y trasmallos de luz de malla de 16 mm se obtienen muchas especies que son posteriormente descartadas así como gran cantidad de peces pequeños, parece claro que estas redes no son convenientes para la pesquería. La luz de malla de 18 mm es la mejor para estas pesquerías multiespecíficas. El uso de paños con esta luz de malla resultaría en una reducción considerable del número de individuos de pequeña talla así como de las especies descartadas.

WOS: 000373863800003, An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5-25 kg, only feeding) and large (>25 kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern high chlorophyll levels latitudes up to the Norwegian Sea in the eastern Atlantic and to the Gulf of Saint Lawrence in the western basin. Permanent suitable feeding habitat for small ABFT was predicted to be mostly located in temperate latitudes in the North Atlantic and in the Mediterranean Sea, as well as in subtropical waters off north-west Africa, while summer potential habitat in the Gulf of Mexico was found to be unsuitable for both small and large ABFTs. Potential spawning grounds were found to occur in the Gulf of Mexico from March April in the south-east to April May in the north, while favourable conditions evolve in the Mediterranean Sea from mid-May in the eastern to mid-July in the western basin. Other secondary potential spawning grounds not supported by observations were predicted in the Azores area and off Morocco to Senegal during July and August when extrapolating the model settings from the Gulf of Mexico into the North Atlantic. The presence of large ABFT off Florida and the Bahamas in spring was not explained by the model as is, however the environmental variables other than the sea surface height anomaly appeared to be favourable for spawning in part of this area. Defining key spatial and temporal habitats should further help in building spatially-explicit stock assessment models, thus improving the spatial management of bluefin tuna fisheries. (C) 2016 The Authors. Published by Elsevier Ltd.