Análisis de la explotación del pez espada Xiphias gladius y de la tintorera Prionace glauca por la flota palangrera catalana durante el periodo 2010-2015 en el Mediterráneo occidental

Swordfish and blue shark are species exploited by the Catalan longline fleet. The number of longliners registered in Catalonia increased between 2010 and 2015. The period when is not allowed to fish swordfish from 2014 would not meet the biological objectives. This species is overexploited in the Mediterranean Sea. Landed quantities of blue shark increased and could illustrate a possible recovery in this marine zone. The authorities must establish measures for sustainable exploitation.Swordfish and blue shark are species exploited by the Catalan longline fleet. The number of longliners registered in Catalonia increased between 2010 and 2015. The period when is not allowed to fish swordfish from 2014 would not meet the biological objectives. This species is overexploited in the Mediterranean Sea. Landed quantities of blue shark increased and could illustrate a possible recovery in this marine zone. The authorities must establish measures for sustainable exploitation

Fatty acid composition and parasitism of European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) populations in the northern Catalan Sea in the context of changing environmental conditions

The status of sardine and anchovy populations in the northern Mediterranean Sea has been declining in recent decades. In this study, fatty acids and parasitism at different reproductive and feeding stages in these two species were assessed using specimens caught along the northern Catalan coast, in order to assess the links between lipid dynamics, reproduction and feeding in these two species and to contribute towards an explanation of the potential causes of the current poor situation of the stocks. The results support the use of fatty acid levels as indicators of the body condition of sardine and anchovy at different reproductive and feeding stages, as well as that of the pelagic environmental conditions. In particular, the relatively low n-3 polyunsaturated fatty acid levels found in spawning sardines compared to spawning anchovies indicate a poorer reproductive health status of sardine. By comparing the current total lipid content values with those recorded in other Mediterranean and North Atlantic areas, and others from more than 10 years ago, in the adjacent area of the Gulf of Lion, our study reveals the persistent poor condition of sardine and anchovy in the northern Catalan Sea. Furthermore, the low levels of diatom fatty acid markers observed throughout the spawning and non-spawning seasons in both sardine and anchovy indicate a diet poor in diatoms. Moreover, the results indicate that it is very unlikely that parasitism is a significant factor in the decline in condition of sardine and anchovy in the northern Catalan Sea. In fact, the results, which we believe provide useful insights for the management of small pelagic fisheries in the Mediterranean, suggest that the current poor condition of sardine and anchovy in the northern Catalan Sea has probably been exacerbated by a decrease in plankton productivity and/or a shift in the taxonomic composition of phytoplankton communities, adding to the ongoing effects of overfishing.info:eu-repo/semantics/publishedVersio

Origins of the Greenland shark (Somniosus microcephalus): Impacts of ice-olation and introgression

Herein, we use genetic data from 277 sleeper sharks to perform coalescent-based modeling to test the hypothesis of early Quaternary emergence of the Greenland shark (Somniosus microcephalus) from ancestral sleeper sharks in the Canadian Arctic-Subarctic region. Our results show that morphologically cryptic somniosids S. microcephalus and Somniosus pacificus can be genetically distinguished using combined mitochondrial and nuclear DNA markers. Our data confirm the presence of genetically admixed individuals in the Canadian Arctic and sub-Arctic, and temperate Eastern Atlantic regions, suggesting introgressive hybridization upon secondary contact following the initial species divergence. Conservative substitution rates fitted to an Isolation with Migration (IM) model indicate a likely species divergence time of 2.34 Ma, using the mitochondrial sequence DNA, which in conjunction with the geographic distribution of admixtures and Pacific signatures likely indicates speciation associated with processes other than the closing of the Isthmus of Panama. This time span coincides with further planetary cooling in the early Quaternary period followed by the onset of oscillating glacial-interglacial cycles. We propose that the initial S. microcephalus–S. pacificus split, and subsequent hybridization events, were likely associated with the onset of Pleistocene glacial oscillations, whereby fluctuating sea levels constrained connectivity among Arctic oceanic basins, Arctic marginal seas, and the North Atlantic Ocean. Our data demonstrates support for the evolutionary consequences of oscillatory vicariance via transient oceanic isolation with subsequent secondary contact associated with fluctuating sea levels throughout the Quaternary period—which may serve as a model for the origins of Arctic marine fauna on a broad taxonomic scale

Explotación intensiva de la tintorera Prionace glauca y del marrajo Isurus oxyrinchus : análisis de la pesquería en el Atlántico noreste entre 2001 y 2016

International audienc

Análisis de la pesca española en el Atlántico noreste 1980-2012: Papel de Galicia en la explotación de las principales especies marinas

The Spanish fishing fleet is one of the most important in the European Union and is exploiting marine resources in the FAO area 27 (North-eastern Atlantic Ocean). The Galician Region has a relevant role in the fishing industry. The number of boats decreased significantly between 1980 and 2012. But the landing quantities of the main marine species exploited (small pelagic fishes and tuna species mainly) decreased faster that the fleet during the same period. In contrast, landing quantities of Elasmobranchs (sharks and rays) and Cephalopods increased. This analysis shows the overexploitation of the Atlantic fishing grounds

La pêche potentielle non-durable d’un requin pélagique en danger critique : le cas du requin peau-bleue (Prionace glauca) en mer Méditerranée occidentale

4 pages, 4 figures[EN] The blue shark (Prionace glauca) is a pelagic, highly migratory shark commonly considered to be a by-catch species of small-scale pelagic longline fisheries. It has been listed by the IUCN as “critically endangered” in the Mediterranean Sea since 2016, but no measure has been taken so far to control its exploitation there. This study analyses the trends in this fishery over recent years in Spanish Mediterranean waters. The results show that blue sharks are now facing considerable fishing pressure, particularly from the long line industrial fleet based in the Andalusian region. Indeed, the results indicate that the blue shark can no longer be considered as a by-catch species and has now become a target species for these fishermen. We suggest measures should be taken urgently to regulate this fishery and that further studies be carried out to determine whether or not this species should be fished any longer in this area[FR] Le requin peau-bleue (Prionace glauca) est un requin pélagique, hautement migrateur, qui est classé depuis 2016 en “danger critique” par l’UIuiCN en mer Méditerranée, mais les autorités n’ont à ce jour adopté aucune mesure pour contrôler son exploitation. Il est communément considéré comme capture accessoire des pêcheries palangrières artisanales. Notre étude analyse les tendances au sein de cette pêcherie durant ces dernières années dans les eaux Méditerranéennes espagnoles. Les résultats montrent que le requin peau-bleue subit une forte pression des flottes palangrières, particulièrement de la flotte industrielle andalouse. Les résultats suggèrent que le requin peau-bleue ne peut plus être considéré comme une espèce accessoire mais qu’il est délibérément ciblé par les pêcheurs. Cela impliquerait la prise de mesures urgentes pour réguler la pêche, de même que de nouvelles études pour savoir si, oui ou non, la pêche au requin peau-bleue peut se poursuivre dans cette zone du globePeer reviewe

Impacts potentiels du chalutage de fond sur les raies (Rajiformes: Rajidae) : le cas du golfe de Cadix et de l’ouest de la Méditerranée

9 pages, 5 figures, 3 tables, 1 appendix[EN] Chondrichthyans such as sharks, rays and chimaeras are highly vulnerable to fishing pressures due to their life history traits. However, there is still little knowledge surrounding the impact of fishing on species of skate in the Mediterranean Sea and the Atlantic Ocean. Using data from historical records, landings and vulnerability of the species, this study analyses the potential impact of trawling on species of skate in two areas: the western Mediterranean (Alboran Sea) and the Gulf of Cádiz. Results show that trawling mainly affects one species in the western Mediterranean, the starry ray (Raja asterias). In the Gulf of Cádiz, the three skate species that are mainly affected are the thornback ray (Raja clavata), the starry ray (R. asterias) and the undulate skate (R. undulata), but also five other species were caught in the same area, Leucoraja naveus, L. circularis, Raja brachyura, R. miraletus and R. montagui. Vulnerability assessment of the species indicate that all skate species, except Raja asterias, R. miraletus and R. montagui, achieve high vulnerability index (i.e. IV > 60) and all (except R miraletus and R. montagui) are classified in the IUCN Red List as near threatened or endangered species. Based on the results, this study proposes recommendations for measures to protect skates from trawling in these areas[FR] Les chondrichthyens tels que les requins, raies et chimères sont hautement vulnérables à la pression de la pêche en raison de leur mode de vie. Cependant, l’impact de la pêche sur les espèces de raies reste à préciser en Méditerranée et en Atlantique. En se basant sur des données historiques, de débarquements et des indices de vulnérabilité, cette étude analyse l’impact potentiel des chalutiers sur les raies dans deux zones distinctes : l’ouest de la Méditerranée (mer d’Alboran) et le golfe de Cadix. Les résultats montrent que le chalut de fond affecte une espèce à l’ouest de la Méditerranée, la raie étoilée (Raja asterias). Dans le golfe de Cadix, les trois espèces de raies qui sont principalement affectées sont la raie bouclée (R. clavata), la raie étoilée (R. asterias) et la raie brunette (R. undulata), mais cinq autres espèces de raies sont également capturées dans la même zone, Leucoraja naveus, L. circularis, Raja brachyura, R. miraletus et R. montagui. L’étude sur la vulnérabilité de ces espèces indique que toutes les raies, sauf Raja asterias, R. miraletus et R. montagui, sont hautement vulnérables avec un indice élevé (i.e. IV > 60) et que toutes les raies (sauf R. miraletus et R. montagui) sont classées dans la liste rouge de l’UICN comme “presque menacé” ou “en danger”. À partir de ces résultats, l’étude recommande des mesures de protection concernant le chalutage dans ces régionsPeer reviewe

Estimating the effects of recreational fisheries on sharks in the English Channel and adjacent seas using social networks

8 pages, 2 figures, 2 tables, supplementary data https://doi.org/10.1016/j.rsma.2023.102978Recreational shark fishing in the English Channel and adjacent seas was analysed through the analysis of videos posted on social networks, which, for the first time, allowed us to assess which species in the area are the most affected by fishing techniques, the hotspots and the biological data of the species caught. Using this novel methodology, we found that recreational anglers target spotted and common smooth-hound sharks (Mustelus asterias and M. mustelus), particularly in French waters. Anglers also target the blue shark (Prionace glauca) and tope (Galeorhinus galeus), mainly in the waters of the United Kingdom (UK). Results show that recreational fishing has implications for the conservation of all these vulnerable species, and particularly for blue shark and tope since, respectively, 49% and 36% of the individuals of these two species caught were juveniles. Based on the results, we propose some recommendations to reduce fishing pressure on these species which should be implemented on a collaborative basis between France and UK for this shared resourceWith the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe