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Coulon N, Pilet S, Lizé A, Lacoue-Labarthe T, Sturbois A, Toussaint A, Feunteun E, Carpentier A. Shark critical life stage vulnerability to monthly temperature variations under climate change. MARINE ENVIRONMENTAL RESEARCH 2024; 198:106531. [PMID: 38696933 DOI: 10.1016/j.marenvres.2024.106531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/22/2024] [Accepted: 04/28/2024] [Indexed: 05/04/2024]
Abstract
In a 10-month experimental study, we assessed the combined impact of warming and acidification on critical life stages of small-spotted catshark (Scyliorhinus canicula). Using recently developed frameworks, we disentangled individual and group responses to two climate scenarios projected for 2100 (SSP2-4.5: Middle of the road and SSP5-8.5: Fossil-fueled Development). Seasonal temperature fluctuations revealed the acute vulnerability of embryos to summer temperatures, with hatching success ranging from 82% for the control and SSP2-4.5 treatments to only 11% for the SSP5-8.5 treatment. The death of embryos was preceded by distinct individual growth trajectories between the treatments, and also revealed inter-individual variations within treatments. Embryos with the lowest hatching success had lower yolk consumption rates, and growth rates associated with a lower energy assimilation, and almost all of them failed to transition to internal gills. Within 6 months after hatching, no additional mortality was observed due to cooler temperatures.
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Affiliation(s)
- Noémie Coulon
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) MNHN, CNRS, IRD, SU, UCN, UA, Station Marine de Dinard, Dinard, France.
| | - Stanislas Pilet
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) MNHN, CNRS, IRD, SU, UCN, UA, Station Marine de Dinard, Dinard, France
| | - Anne Lizé
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) MNHN, CNRS, IRD, SU, UCN, UA, Station Marine de Dinard, Dinard, France; School of Life Sciences, University of Liverpool, Liverpool, UK
| | - Thomas Lacoue-Labarthe
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266, CNRS-Université de La Rochelle, La Rochelle, France
| | - Anthony Sturbois
- VivArmor Nature, Réserve Naturelle Nationale de la Baie de Saint-Brieuc, Laboratoire des Sciences de l'environnement Marin (LEMAR), UMR 6539, France
| | - Aurèle Toussaint
- Centre de Recherche sur la Biodiversité et l'Environnement (CRBE), UMR5300 - UPS-CNRS-IRD-INP, Université Paul-Sabatier - Toulouse 3, Toulouse, France
| | - Eric Feunteun
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) MNHN, CNRS, IRD, SU, UCN, UA, Station Marine de Dinard, Dinard, France; Centre de GéoEcologie Littorale (CGEL, EPHE-PSL), Dinard, France
| | - Alexandre Carpentier
- Université de Rennes, Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) MNHN, CNRS, IRD, SU, UCN, UA, Campus de Beaulieu, Rennes, France
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2
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Hermans A, Winter HV, Gill AB, Murk AJ. Do electromagnetic fields from subsea power cables effect benthic elasmobranch behaviour? A risk-based approach for the Dutch Continental Shelf. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123570. [PMID: 38360387 DOI: 10.1016/j.envpol.2024.123570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 02/11/2024] [Accepted: 02/12/2024] [Indexed: 02/17/2024]
Abstract
Subsea power cables cause electromagnetic fields (EMFs) into the marine environment. Elasmobranchs (rays, skates, sharks) are particularly sensitive to EMFs as they use electromagnetic-receptive sensory systems for orientation, navigation, and locating conspecifics or buried prey. Cables may intersect with egg laying sites, mating, pupping, and nursery grounds, foraging habitat and migration routes of elasmobranchs and the effects of encountering EMFs on species of elasmobranchs are largely unknown. Demonstrated behavioural effects are attraction, disturbance and indifference, depending on EMF characteristics, exposed life stage, exposure level and duration. We estimated exposure levels of elasmobranchs to subsea power cable EMFs, based on modelled magnetic fields in the Dutch Continental Shelf and compared these to reported elasmobranch sensory sensitivity ranges and experimental effect levels. We conclude that the risk from subsea power cables has a large uncertainty and varies per life stage and species ecology. Based on estimated no-observed effect levels (from 10-3 to 10-1 μT) we discuss what will probably be the most affected species and life stage for six common benthic elasmobranchs in the Southern North Sea. We then identify critical knowledge gaps for reducing the uncertainty in the risk assessments for EMFs effects on benthic elasmobranchs.
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Affiliation(s)
- Annemiek Hermans
- Marine Animal Ecology Group, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, the Netherlands.
| | - Hendrik V Winter
- Wageningen Marine Research, Wageningen University and Research, P.O. 68, 1970 AB, IJmuiden, the Netherlands
| | - Andrew B Gill
- Cefas, Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, Suffolk, NR33 0HT, UK
| | - Albertinka J Murk
- Marine Animal Ecology Group, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, the Netherlands
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3
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McAllister M, Fraser S, Henry LA. Population ecology and juvenile density hotspots of thornback ray (Raja clavata) around the Shetland Islands, Scotland. JOURNAL OF FISH BIOLOGY 2024; 104:576-589. [PMID: 37934068 DOI: 10.1111/jfb.15610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 10/26/2023] [Accepted: 11/03/2023] [Indexed: 11/08/2023]
Abstract
Elasmobranchs are facing global decline, and so there is a pressing need for research into their populations to inform effective conservation and management strategies. Little information exists on the population ecology of skate species around the British Isles, presenting an important knowledge gap that this study aimed to reduce. The population ecology of thornback ray (Raja clavata) around the Shetland Islands, Scotland, was investigated in two habitats: inshore (50-150 m deep) and shallow coastal (20-50 m deep), from 2011 to 2022, and 2017 to 2022, respectively. Using trawl survey data from the annual Shetland Inshore Fish Survey, the size composition of R. clavata catches was compared between shallow and inshore habitats across 157 trawl sets, and 885 individuals, over the years 2017-2022. Catch per unit effort (CPUE) of R. clavata was significantly higher in shallow than that in inshore areas (ANOVA, F = 72.52, df = 1, 5, p < 0.001). Size composition also significantly differed between the two habitats (analysis of similarities, R = 0.96, p = 0.002), with R. clavata being smaller in shallow areas and juveniles (<60 cm) occurring more frequently. Spatial distribution maps confirmed density hotspots of juveniles in shallow habitats, with repeated use of certain locations consistent over time. The results of this study provide the first evidence for R. clavata using shallow areas for potential nurseries in Shetland, which can inform the IUCN's Important Shark and Ray Area process. Furthermore, this study provides important new population ecology information for R. clavata around Shetland, which may have important conservation implications and be valuable for informing species and fisheries stock assessments in this region.
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Affiliation(s)
- Mia McAllister
- Marine Science Department, UHI Shetland, University of the Highlands and Islands, Scalloway Campus, Shetland, UK
| | - Shaun Fraser
- Marine Science Department, UHI Shetland, University of the Highlands and Islands, Scalloway Campus, Shetland, UK
| | - Lea-Anne Henry
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
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4
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Coulon N, Elliott S, Teichert N, Auber A, McLean M, Barreau T, Feunteun E, Carpentier A. Northeast Atlantic elasmobranch community on the move: Functional reorganization in response to climate change. GLOBAL CHANGE BIOLOGY 2024; 30:e17157. [PMID: 38273525 DOI: 10.1111/gcb.17157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/15/2023] [Accepted: 01/05/2024] [Indexed: 01/27/2024]
Abstract
While spatial distribution shifts have been documented in many marine fishes under global change, the responses of elasmobranchs have rarely been studied, which may have led to an underestimation of their potential additional threats. Given their irreplaceable role in ecosystems and their high extinction risk, we used a 24-year time series (1997-2020) of scientific bottom trawl surveys to examine the effects of climate change on the spatial distribution of nine elasmobranch species within Northeast Atlantic waters. Using a hierarchical modeling of species communities, belonging to the joint species distribution models, we found that suitable habitats for four species increased on average by a factor of 1.6 and, for six species, shifted north-eastwards and/or to deeper waters over the past two decades. By integrating species traits, we showed changes in habitat suitability led to changes in the elasmobranchs trait composition. Moreover, communities shifted to deeper waters and their mean trophic level decreased. We also note an increase in the mean community size at maturity concurrent with a decrease in fecundity. Because skates and sharks are functionally unique and dangerously vulnerable to both climate change and fishing, we advocate for urgent considerations of species traits in management measures. Their use would make it better to identify species whose loss could have irreversible impacts in face of the myriad of anthropogenic threats.
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Affiliation(s)
- Noémie Coulon
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN, CNRS, IRD, SU, UCN, UA, Dinard, France
| | - Sophie Elliott
- Salmon & Trout Research Centre, Game & Wildlife Conservation Trust, Wareham, UK
| | - Nils Teichert
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN, CNRS, IRD, SU, UCN, UA, Dinard, France
| | - Arnaud Auber
- Unité Halieutique Manche Mer du Nord, Laboratoire Ressources Halieutiques, IFREMER, Boulogne-sur-Mer, France
| | - Matthew McLean
- Department of Biology and Marine Biology, Center for Marine Science, University of North Carolina Wilmington, Wilmington, North Carolina, USA
| | - Thomas Barreau
- Service des Stations Marine, Station Marine de Dinard, Dinard, France
| | - Eric Feunteun
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN, CNRS, IRD, SU, UCN, UA, Dinard, France
| | - Alexandre Carpentier
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN, CNRS, IRD, SU, UCN, UA, Campus de Beaulieu, Université de Rennes, Rennes, France
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5
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Morphological Traits and Capture Depth of the Norwegian Skate (Dipturus nidarosiensis (Storm, 1881)) from Two Mediterranean Populations. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2021. [DOI: 10.3390/jmse9121462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Norwegian skate Dipturus nidarosiensis (Storm, 1881) has only recently been recorded in the western-central Mediterranean Sea. It was hypothesized a more ancient presence of the species, which has not been detected due to a misidentification with other species of the same genus. This situation could lead to underestimate the risk of a dramatic decline of the spawning stock. In the IUCN Red List, the species is listed as near threatened and considered rare in both the northeast Atlantic and the Mediterranean areas. In the Mediterranean Sea, Norwegian skates were repeatedly caught mostly in two areas between 2005 and 2020: Sardinia Seas and Adriatic-Ionian Seas. In total, 58 specimens were caught, and 28 morphological length measurements were taken on all specimens. The Canonical Discriminant Analysis proved the presence of significant differences only for assemblages made on the basis of the specimen’s area of capture, but not on the basis of sex or ontogenetic development. This analysis could be the first step to highlight the differences between the populations of Norwegian skate in the Mediterranean basin. Moreover, a preliminary analysis of depth of capture was performed as a first step to study this species vertical distribution.
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Biological Knowledge of Thornback Ray ( Raja clavata) from the Azores: Improving Scientific Information for the Effectiveness of Species-Specific Management Measures. BIOLOGY 2021; 10:biology10070676. [PMID: 34356531 PMCID: PMC8301307 DOI: 10.3390/biology10070676] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/06/2021] [Accepted: 07/16/2021] [Indexed: 11/16/2022]
Abstract
Simple Summary Sharks, rays, and skates are increasingly being recognized as endangered due to their life-history characteristics, fishing pressure, and habitat degradation. The thornback ray Raja clavata is one of the most commercially important skates in the seas of Northwest Europe. However, due to a lack of biological knowledge about this species in Azorean waters, the types of stock evaluations that can be performed are restricted. This study expands current knowledge on vertical distribution, size-frequency distributions, growth patterns, sex ratios, mortality rates, and reproduction of this species, and provides a baseline for further fishing monitoring. Abstract Elasmobranchs are globally recognized as vulnerable due to their life-history characteristics, fishing pressure, and habitat degradation. Among the skates and rays caught by commercial fisheries, the thornback ray Raja clavata is one of the most economically important in Northwest European seas. However, the scarcity of biological knowledge about this species in Azorean waters has limited the stock assessment types that can be conducted. To improve information on its habitat preferences, spatial distribution and movement pattern, growth, sex ratio, mortality, and reproduction, as well as to investigate long-term changes in abundance and size, this study analyzed approximately 25 years of fishery-dependent and independent data from the Azores. Raja clavata was mainly caught at depths up to 250 m. Most of the tagged fish were recaptured near the release point. A larger–deeper trend was found, and females were larger and more abundant than males. Life-history parameters showed that R. clavata has a long lifespan, large size, slow growth, and low natural mortality. The sustainability of its population is of concern to fisheries management and, while our findings suggested a relatively healthy stock in the Azores, a thorough increase in data quality is required to better understand the stock condition and prevent overexploitation.
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Kousteni V. Shedding light on the deep: The case of the velvet belly lanternshark in the North Aegean Sea. JOURNAL OF FISH BIOLOGY 2021; 99:101-117. [PMID: 33587314 DOI: 10.1111/jfb.14702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/13/2021] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Main biological features were assessed for the first time in the deep-water shark Etmopterus spinax from Hellenic waters by examining 150 individuals caught incidentally in the bottom-trawl commercial fishery off Skyros island. Females outnumbered males and the overall sex ratio was 1.38:1. Females ranged from 122 to 311 mm in total length (LT ) and males from 129 to 270 mm LT , both exhibiting positive allometric growth. Total length-total mass relationships and frequency distributions did not show significant differences between females and males. Sexual dimorphism was not either found by analysing 56 different morphological characteristics. The effect of sex and season was more prominent on the gonadosomatic and hepatosomatic indices compared to the relative condition factor. Most of the individuals were sexually immature, with two specimens classified as mature, one gravid female reaching 311 mm LT with undeveloped gonads and enlarged uteri with embryos, and one male reaching 270 mm LT with enlarged gonads and rigid claspers with hooks. The present study highlights the importance of the sampling location as a breeding and nursery ground for E. spinax in the eastern Mediterranean Sea that should be taken into account for the species' conservation considering its intrinsic characteristics, which make it vulnerable to fishing pressure.
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Affiliation(s)
- Vasiliki Kousteni
- Fisheries Research Institute, Hellenic Agricultural Organization-Demeter, Kavala, Greece
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8
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Hermans R, Vanhove MPM, Ditrich O, Tyml T, Gelnar M, Artois T, Kmentová N. Parasitic flatworms infecting thorny skate, Amblyraja radiata: Infection by the monogeneans Acanthocotyle verrilli and Rajonchocotyle emarginata in Svalbard. Parasitol Int 2020; 81:102261. [PMID: 33276144 DOI: 10.1016/j.parint.2020.102261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 10/22/2022]
Abstract
Parasite diversity above the Arctic circle remains understudied even for commercially valuable host taxa. Thorny skate, Amblyraja radiata, is a common bycatch species with a growing commercial value. Its natural range covers both sides of the North Atlantic including the Arctic zone. Svalbard is a Norwegian archipelago located on the northwest corner of the Barents Shelf which sustains a spectacular species diversity. So far, several monogenean species have been reported infecting thorny skate across the Atlantic Ocean. In the present study, we intend to fill in the knowledge gap on monogenean parasites infecting thorny skate in the northern part of its range and thus indirectly assess the connectivity between the thorny skate populations off the Svalbard coast and from previously studied locations. 46 monogenean individuals were recovered from 11 specimens of thorny skate. Following morphological and molecular assessment, two species of monogeneans, Acanthocotyle verrilli and Rajonchocotyle emarginata, were identified. The results serve as the northernmost record for both parasite genera and the first record of monogenean species off Svalbard. Detailed morphometric evaluation revealed a relatively high level of morphological variation in A. verrilli compared to its congeners. Phylogenetic reconstruction placed A. verrilli in a well-supported clade with A. imo. Our study also suggests high diagnostic significance of sclerotised structures in the identification of Rajonchocotyle. Even though the occurrence of two directly transmitted parasite species supports the previously suggested long-distance migration of A. radiata, future studies employing highly variable genetic markers are needed to assess the ongoing and historical migration patterns.
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Affiliation(s)
- Raquel Hermans
- Research Group Zoology: Biodiversity & Toxicology, Centre for Environmental Sciences, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Maarten P M Vanhove
- Research Group Zoology: Biodiversity & Toxicology, Centre for Environmental Sciences, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium; Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Oleg Ditrich
- Centre for Polar Ecology, Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Tomáš Tyml
- Centre for Polar Ecology, Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Milan Gelnar
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Tom Artois
- Research Group Zoology: Biodiversity & Toxicology, Centre for Environmental Sciences, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Nikol Kmentová
- Research Group Zoology: Biodiversity & Toxicology, Centre for Environmental Sciences, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium; Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic.
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Griffiths CA, Wright SR, Silva JF, Ellis JR, Righton DA, McCully Phillips SR. Horizontal and vertical movements of starry smooth-hound Mustelus asterias in the northeast Atlantic. PLoS One 2020; 15:e0239480. [PMID: 33112858 PMCID: PMC7592766 DOI: 10.1371/journal.pone.0239480] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 09/07/2020] [Indexed: 11/19/2022] Open
Abstract
Commercial landings of starry smooth-hound Mustelus asterias in northern European seas are increasing, whilst our knowledge of their ecology, behaviour and population structure remains limited. M. asterias is a widely distributed demersal shark, occupying the waters of the southern North Sea and Irish Sea in the north, to at least the southern Bay of Biscay in the south, and is seasonally abundant in UK waters. There are no species-specific management measures for the northeast Atlantic stock, and the complexity of its population structure is not yet fully understood. To address this issue, we deployed both mark-recapture and electronic tags on M. asterias to gain novel insights into its horizontal and vertical movements. Our data suggest that the habitat use of M. asterias changes on a seasonal basis, with associated changes in geographical distribution, depth utilisation and experienced temperature. We report the first direct evidence of philopatry for this species, and also provide initial evidence of sex-biased dispersal and potential metapopulation-like stock structuring either side of the UK continental shelf. Investigations of finer-scale vertical movements revealed clear diel variation in vertical activity. The illustrated patterns of seasonal space-use and behaviour will provide important information to support the stock assessment process and will help inform any future management options.
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Affiliation(s)
- Christopher A. Griffiths
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, Suffolk, United Kingdom
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Serena R. Wright
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, Suffolk, United Kingdom
| | - Joana F. Silva
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, Suffolk, United Kingdom
| | - Jim R. Ellis
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, Suffolk, United Kingdom
| | - David A. Righton
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, Suffolk, United Kingdom
| | - Sophy R. McCully Phillips
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, Suffolk, United Kingdom
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10
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Thorburn J, Neat F, Burrett I, Henry LA, Bailey DM, Jones CS, Noble LR. Ontogenetic Variation in Movements and Depth Use, and Evidence of Partial Migration in a Benthopelagic Elasmobranch. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00353] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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11
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Carbonara P, Cannas R, Donnaloia M, Melis R, Porcu C, Spedicato MT, Zupa W, Follesa MC. On the presence of Dipturus nidarosiensis (Storm, 1881) in the Central Mediterranean area. PeerJ 2019; 7:e7009. [PMID: 31179191 PMCID: PMC6542346 DOI: 10.7717/peerj.7009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/24/2019] [Indexed: 11/26/2022] Open
Abstract
The Norwegian skate Dipturus nidarosiensis (Storm, 1881) has only recently been recorded in the western Mediterranean Sea along the coast of southern Sardinia, off Algeria and the Alboran Sea. The present study confirmed the presence of the species in the Central Mediterranean Sea by identifying morphometric, morphological features and molecular markers. Biological sampling was conducted from 2010 to 2016 on eight specimens collected through commercial landings, offshore observer programmes and scientific surveys in Adriatic and Ionian waters at depths between 320 and 720 m. The total lengths of the specimens (juveniles and adults) ranged from 268 to 1,422 mm, and their body weights ranged from 44.5 to 12,540.0 g. They showed morphometric features that corresponded to those of Norwegian skates in the Northeast Atlantic and the Western Mediterranean. In previous analyses, molecular data were obtained by mitochondrial COI sequences. The haplotype network showed the occurrence of a common haplotype (Hap_1) shared by the individuals from areas in the North Atlantic, Sardinian, Algerian and Spanish Mediterranean Sea areas but not South Africa. The occurrence of individuals in different stages of life (i.e., juveniles, sub-adults and adults) and sexual development (immature and mature) suggested the presence of a species with a permanent reproductive allocation in the deep waters of the Mediterranean, which was exposed to a low level of fishing exploitation. Indeed, the deep depth distribution of the species could be the reason for the absence of information about this species in onshore or offshore fishery data collection programmes and scientific surveys.
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Affiliation(s)
- Pierluigi Carbonara
- COISPA Tecnologia & Ricerca, Stazione Sperimentale per lo Studio delle Risorse del Mare, Bari, Italy
| | - Rita Cannas
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Marilena Donnaloia
- COISPA Tecnologia & Ricerca, Stazione Sperimentale per lo Studio delle Risorse del Mare, Bari, Italy
| | - Riccardo Melis
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Cristina Porcu
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Maria Teresa Spedicato
- COISPA Tecnologia & Ricerca, Stazione Sperimentale per lo Studio delle Risorse del Mare, Bari, Italy
| | - Walter Zupa
- COISPA Tecnologia & Ricerca, Stazione Sperimentale per lo Studio delle Risorse del Mare, Bari, Italy
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12
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Dureuil M, Boerder K, Burnett KA, Froese R, Worm B. Elevated trawling inside protected areas undermines conservation outcomes in a global fishing hot spot. Science 2019; 362:1403-1407. [PMID: 30573625 DOI: 10.1126/science.aau0561] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 11/07/2018] [Indexed: 01/08/2023]
Abstract
Marine protected areas (MPAs) are increasingly used as a primary tool to conserve biodiversity. This is particularly relevant in heavily exploited fisheries hot spots such as Europe, where MPAs now cover 29% of territorial waters, with unknown effects on fishing pressure and conservation outcomes. We investigated industrial trawl fishing and sensitive indicator species in and around 727 MPAs designated by the European Union. We found that 59% of MPAs are commercially trawled, and average trawling intensity across MPAs is at least 1.4-fold higher as compared with nonprotected areas. Abundance of sensitive species (sharks, rays, and skates) decreased by 69% in heavily trawled areas. The widespread industrial exploitation of MPAs undermines global biodiversity conservation targets, elevating recent concerns about growing human pressures on protected areas worldwide.
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Affiliation(s)
- Manuel Dureuil
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada. .,Sharks of the Atlantic Research and Conservation Centre, Halifax, NS B3L 2Y5, Canada
| | - Kristina Boerder
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Kirsti A Burnett
- Sharks of the Atlantic Research and Conservation Centre, Halifax, NS B3L 2Y5, Canada
| | - Rainer Froese
- GEOMAR Helmholtz Centre for Ocean Research, 24105 Kiel, Germany
| | - Boris Worm
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Brevé NWP, Winter HV, Van Overzee HMJ, Farrell ED, Walker PA. Seasonal migration of the starry smooth-hound shark Mustelus asterias as revealed from tag-recapture data of an angler-led tagging programme. JOURNAL OF FISH BIOLOGY 2016; 89:1158-1177. [PMID: 27220775 DOI: 10.1111/jfb.12994] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 04/07/2016] [Indexed: 06/05/2023]
Abstract
The primary aim of this long-term angler-led tagging programme was to gain information about seasonal changes in distribution of the starry smooth-hound shark Mustelus asterias, along the Dutch coast for management and conservation purposes. Between 2011 and 2014, M. asterias comprised 92·6% (n = 2418) of the total elasmobranch catch (n = 2612) by the licenced group of taggers within the Dutch Delta of which 2244 M. asterias were fin-tagged with plastic rototags. Sex and total length (LT ) composition inside the eastern tidal basin (Oosterschelde) were significantly different, i.e. more females and larger individuals, than outside indicating a pupping ground, which was confirmed by the capture of 30 newborn pups (≤32 cm). The distribution pattern of reported recaptured M. asterias (return-rate 3·6%, n = 80) showed a circannual migration between summering in the southern North Sea and wintering in the English Channel and the Bay of Biscay, and suggests that M. asterias is philopatric. The Dutch angling season for M. asterias runs from approximately mid-May to mid-October when the water temperature is above 13° C. Recaptures of eight mature females, but no males in the Bay of Biscay, indicate partial spatial segregation by sex, where mature females migrate over larger distances than immature females and males. These observations, with the absence of recaptures in other known summering areas (i.e. the Irish Sea and Bristol Channel), suggest that the southern North Sea is used by a separate population. Implications for management and recommendations to improve and expand the study approach are discussed.
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Affiliation(s)
- N W P Brevé
- Sportvisserij Nederland, Leijenseweg 115, 3721 BC, Bilthoven, the Netherlands
| | - H V Winter
- IMARES, Wageningen UR, Haringkade 1, 1976 CP, IJmuiden, the Netherlands
| | - H M J Van Overzee
- IMARES, Wageningen UR, Haringkade 1, 1976 CP, IJmuiden, the Netherlands
| | - E D Farrell
- School of Biology & Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin, 4, Ireland
| | - P A Walker
- Van Hall Larenstein University of Applied Sciences, Agora 1, 8934 CJ, Leeuwarden, the Netherlands
- Dutch Elasmobranch Society, Hobbemakade 118-hs, 1071 XW, Amsterdam, the Netherlands
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Hoff GR. Identification of multiple nursery habitats of skates in the eastern Bering Sea. JOURNAL OF FISH BIOLOGY 2016; 88:1746-1757. [PMID: 27062636 DOI: 10.1111/jfb.12939] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/04/2016] [Indexed: 06/05/2023]
Abstract
The use of more than a single nursery habitat type is examined for oviparous elasmobranchs using data summarized from studies conducted on the Alaska skate Bathyraja parmifera and the Aleutian skate Bathyraja aleutica in the eastern Bering Sea. The eastern Bering Sea skate species use two discrete areas as nurseries, one for egg deposition and a second for newly emergent juveniles. Egg deposition sites were located along the outer shelf and upper slope near canyons in the eastern Bering Sea. Newly emergent juveniles were found along the outer and middle shelf for B. parmifera and deep-slope for B. aleutica, suggesting that habitat used by newly emergent juvenile skates is distinct from habitat used for egg deposition and embryo development. In reviewing many studies on oviparous elasmobranchs, similar patterns emerge of habitat use during their early life history. To distinguish these distinct habitats, appropriate terminology is proposed. Egg case nursery is suggested for areas of egg deposition and juvenile nursery is suggested for areas where juveniles aggregate after emergence. Criteria to describe each habitat type are outlined.
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Affiliation(s)
- G R Hoff
- Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, 7600 Sand Point Way NE, Seattle, WA 98115, U.S.A
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Johnson MS, Kraver DW, Renshaw GMC, Rummer JL. Will ocean acidification affect the early ontogeny of a tropical oviparous elasmobranch (Hemiscyllium ocellatum)? CONSERVATION PHYSIOLOGY 2016; 4:cow003. [PMID: 27293755 PMCID: PMC4784014 DOI: 10.1093/conphys/cow003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Revised: 12/22/2015] [Accepted: 01/25/2016] [Indexed: 06/06/2023]
Abstract
Atmospheric CO2 is increasing due to anthropogenic causes. Approximately 30% of this CO2 is being absorbed by the oceans and is causing ocean acidification (OA). The effects of OA on calcifying organisms are starting to be understood, but less is known about the effects on non-calcifying organisms, notably elasmobranchs. One of the few elasmobranch species that has been studied with respect to OA is the epaulette shark, Hemiscyllium ocellatum. Mature epaulette sharks can physiologically and behaviourally tolerate prolonged exposure to elevated CO2, and this is thought to be because they are routinely exposed to diurnal decreases in O2 and probably concomitant increases in CO2 in their coral reef habitats. It follows that H. ocellatum embryos, while developing in ovo on the reefs, would have to be equally if not more tolerant than adults because they would not be able to escape such conditions. Epaulette shark eggs were exposed to either present-day control conditions (420 µatm) or elevated CO2 (945 µatm) and observed every 3 days from 10 days post-fertilization until 30 days post-hatching. Growth (in square centimetres per day), yolk usage (as a percentage), tail oscillations (per minute), gill movements (per minute) and survival were not significantly different in embryos reared in control conditions when compared with those reared in elevated CO2 conditions. Overall, these findings emphasize the importance of investigating early life-history stages, as the consequences are expected to transfer not only to the success of an individual but also to populations and their distribution patterns.
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Affiliation(s)
- Martijn S Johnson
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia
- College of Marine and Environmental Science, James Cook University, Townsville, Queensland 4811, Australia
| | - Daniel W Kraver
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia
- College of Marine and Environmental Science, James Cook University, Townsville, Queensland 4811, Australia
| | - Gillian M C Renshaw
- Hypoxia and Ischemia Research Unit, School of Allied Health Science, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Jodie L Rummer
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia
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Predictive habitat suitability models to aid conservation of elasmobranch diversity in the central Mediterranean Sea. Sci Rep 2015; 5:13245. [PMID: 26272502 PMCID: PMC4536484 DOI: 10.1038/srep13245] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/10/2015] [Indexed: 11/08/2022] Open
Abstract
Commercial fisheries have dramatically impacted elasmobranch populations worldwide. With high capture and bycatch rates, the abundance of many species is rapidly declining and around a quarter of the world's sharks and rays are threatened with extinction. At a regional scale this negative trend has also been evidenced in the central Mediterranean Sea, where bottom-trawl fisheries have affected the biomass of certain rays (e.g. Raja clavata) and sharks (e.g. Mustelus spp.). Detailed knowledge of elasmobranch habitat requirements is essential for biodiversity conservation and fisheries management, but this is often hampered by a poor understanding of their spatial ecology. Habitat suitability models were used to investigate the habitat preference of nine elasmobranch species and their overall diversity (number of species) in relation to five environmental predictors (i.e. depth, sea surface temperature, surface salinity, slope and rugosity) in the central Mediterranean Sea. Results showed that depth, seafloor morphology and sea surface temperature were the main drivers for elasmobranch habitat suitability. Predictive distribution maps revealed different species-specific patterns of suitable habitat while high assemblage diversity was predicted in deeper offshore waters (400-800 m depth). This study helps to identify priority conservation areas and diversity hot-spots for rare and endangered elasmobranchs in the Mediterranean Sea.
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Serra-Pereira B, Erzini K, Figueiredo I. Using biological variables and reproductive strategy of the undulate ray Raja undulata to evaluate productivity and susceptibility to exploitation. JOURNAL OF FISH BIOLOGY 2015; 86:1471-1490. [PMID: 25809468 DOI: 10.1111/jfb.12653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 01/21/2015] [Indexed: 06/04/2023]
Abstract
The present work provides a detailed analysis of the reproductive strategy of the undulate ray Raja undulata in Portuguese mainland waters. The species was found mostly between 30 and 40 m deep on sandy bottoms. Egg-laying sites were observed in the north, centre and south-west regions, mainly at depths below 30 m. The peak of the reproductive season occurred from December to May. Asynchrony between reproductively active females and males appeared to occur, although most adult males were capable of reproducing throughout the year. The estimated length at 50% maturity was 86·2 cm (8·7 years) and 76·8 cm (7·6 years) total length for females and males, respectively. The maximum potential fecundity was estimated to be 69·8 follicles per female per reproductive season, which are released in 4·7 batches of 15 follicles. The life-history and demographic parameters of R. undulata are similar to those of other skate species, while the potential rate of population increase (0·49) is above the published values for other elasmobranch species. With these new findings, this study makes an important contribution to the understanding of the life history of R. undulata, and provides a first evaluation of the productivity and susceptibility of the species to exploitation.
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Affiliation(s)
- B Serra-Pereira
- Instituto Português do Mar e da Atmosfera (IPMA), Departamento do Mar e Recursos Marinhos, Divisão de Modelação e Gestão de Recursos da Pesca, Av. Brasília, 1449-006 Lisboa, Portugal
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Fock HO. Patterns of extirpation. I. Changes in habitat use by thornback rays Raja clavata in the German Bight for 1902-1908, 1930-1932, and 1991-2009. ENDANGER SPECIES RES 2014. [DOI: 10.3354/esr00582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Fock HO, Probst WN, Schaber M. Patterns of extirpation. II. The role of connectivity in the decline and recovery of elasmobranch populations in the German Bight as inferred from survey data. ENDANGER SPECIES RES 2014. [DOI: 10.3354/esr00583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Bustamante C, Vargas-Caro C, Bennett MB. Biogeographic patterns in the cartilaginous fauna (Pisces: Elasmobranchii and Holocephali) in the southeast Pacific Ocean. PeerJ 2014; 2:e416. [PMID: 24918036 PMCID: PMC4045336 DOI: 10.7717/peerj.416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/15/2014] [Indexed: 11/20/2022] Open
Abstract
The abundance and species richness of the cartilaginous fish community of the continental shelf and slope off central Chile is described, based on fishery-independent trawl tows made in 2006 and 2007. A total of 194,705 specimens comprising 20 species (9 sharks, 10 skates, 1 chimaera) were caught at depths of 100-500 m along a 1,000 km transect between 29.5°S and 39°S. Sample site locations were grouped to represent eight geographical zones within this latitudinal range. Species richness fluctuated from 1 to 6 species per zone. There was no significant latitudinal trend for sharks, but skates showed an increased species richness with latitude. Standardised catch per unit effort (CPUE) increased with increasing depth for sharks, but not for skates, but the observed trend for increasing CPUE with latitude was not significant for either sharks or skates. A change in community composition occurred along the depth gradient with the skates, Psammobatis rudis, Zearaja chilensis and Dipturus trachyderma dominating communities between 100 and 300 m, but small-sized, deep-water dogfishes, such as Centroscyllium spp. dominated the catch between 300 and 500 m. Cluster and ordination analysis identified one widespread assemblage, grouping 58% of sites, and three shallow-water assemblages. Assemblages with low diversity (coldspots) coincided with highly productive fishing grounds for demersal crustaceans and bony fishes. The community distribution suggested that the differences between assemblages may be due to compensatory changes in mesopredator species abundance, as a consequence of continuous and unselective species removal. Distribution patterns and the quantitative assessment of sharks, skates and chimaeras presented here complement extant biogeographic knowledge and further the understanding of deep-water ecosystem dynamics in relation to fishing activity in the south-east Pacific Ocean.
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Affiliation(s)
- Carlos Bustamante
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia
- Programa de Conservación de Tiburones (Chile), Valdivia, Chile
| | - Carolina Vargas-Caro
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia
- Programa de Conservación de Tiburones (Chile), Valdivia, Chile
| | - Michael B. Bennett
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia
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22
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Serra-Pereira B, Erzini K, Maia C, Figueiredo I. Identification of potential essential fish habitats for skates based on fishers' knowledge. ENVIRONMENTAL MANAGEMENT 2014; 53:985-998. [PMID: 24573167 DOI: 10.1007/s00267-014-0257-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 02/17/2014] [Indexed: 06/03/2023]
Abstract
Understanding of spatio-temporal patterns of sensitive fish species such as skates (Rajidae) is essential for implementation of conservation measures. With insufficient survey data available for these species in Portuguese Continental waters, this study shows that fishery-dependent data associated with fishers' knowledge can be used to identify potential Essential Fish Habitats (EFH) for seven skate species. Sites with similar geomorphology were associated with the occurrence of juveniles and/or adults of the same group of species. For example, sites deeper than 100 m with soft sediment include predominantly adults of Raja clavata, and are the habitat for egg deposition of this species. Raja undulata and R. microocellata are the more coastal species, preferring sand or gravel habitats, while coastal areas with rocks and sand seabed are potential nursery areas for R. brachyura, R. montagui and R. clavata. The main output of this study is the identification of preferential fishing sites enclosing potential EFH for some species, associated with egg-laying and nursery grounds. The location of these areas will be considered for future seasonal closures, and studies will be conducted to evaluate the biological and socio-economic impacts of such measures. As in the past, fishermen will collaborate in the process of evaluating those impacts, since they have practical and applied knowledge that is extremely valuable for evaluating the advantages and disadvantages of such closures. In conclusion, this study is a first contribution to the understanding and identification of EFH for skate species, associated with nursery and egg deposition sites, with direct application to management.
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Affiliation(s)
- Bárbara Serra-Pereira
- Divisão de Modelação e Gestão de Recursos da Pesca, Departamento do Mar e Recursos Marinhos, Instituto Português do Mar e da Atmosfera (IPMA), Av. Brasília, 1449-006, Lisbon, Portugal,
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Griffiths AM, Miller DD, Egan A, Fox J, Greenfield A, Mariani S. DNA barcoding unveils skate (Chondrichthyes: Rajidae) species diversity in 'ray' products sold across Ireland and the UK. PeerJ 2013; 1:e129. [PMID: 24024082 PMCID: PMC3746960 DOI: 10.7717/peerj.129] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 07/21/2013] [Indexed: 11/20/2022] Open
Abstract
Skates are widely consumed across the globe, but many large species are subject to considerable concern regarding their conservation and management. Within Europe such issues have recently driven policy changes so that, for the first time, reports of skate landings now have to be made under species-specific names. Total allowable catches have also been established for many groups, which have been set to zero for a number of the most vulnerable species (e.g., Dipturus batis, Raja undulata and Rostoraja alba). Whilst accurate species identification has become an important issue for landings, the sale of skates is still usually made under a blanket term of “skate” or “ray”. The matter of identifying species of skate is further complicated by their morphologically conservative nature and the fact that they are commercially valued for their wings. Thus, before sale their bodies are usually discarded (i.e., “winged”) and often skinned, making morphological identification impossible. For the first time, DNA barcoding (of the mitochondrial COI gene) was applied to samples of skate wings from retail outlets across the British Isles, providing insight into which species are sold for consumption. A total of 98 wing samples were analysed, revealing that six species were sold; blonde ray (Raja brachyura), spotted ray (Raja montagui), thornback ray (Raja clavata), cuckoo ray (Leucoraja naevus) small-eyed ray (Raja microocellata) and shagreen ray (Leucoraja fullonica). Statistical testing demonstrated that there were significant differences in the species sold in the distinct retail groups which suggests complex drivers behind the patterns of sale in skates. The results also indicate that endangered species are not commonly being passed on to consumers. In addition, the practice of selling skate wings under ambiguous labels is highlighted as it makes it extremely difficult for consumers to exercise a right to avoid species of conservation concern. Interestingly, a single retailer chain labelled their wings as originating from three smaller-growing species (generally to be considered of lower conservation concern); of the six samples analysed from this company a third were mislabelled and originated from the thornback ray (a larger species that is currently undergoing population declines).
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Affiliation(s)
- Andrew Mark Griffiths
- School of Environment and Life Sciences, University of Salford, Greater Manchester, UK
| | - Dana D Miller
- School of Biology & Environmental Science, Science Education and Research Centre-West, University College Dublin, Belfield, Dublin, Ireland.,Fisheries Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Aaron Egan
- School of Biology & Environmental Science, Science Education and Research Centre-West, University College Dublin, Belfield, Dublin, Ireland
| | - Jennifer Fox
- School of Biology & Environmental Science, Science Education and Research Centre-West, University College Dublin, Belfield, Dublin, Ireland
| | - Adam Greenfield
- School of Environment and Life Sciences, University of Salford, Greater Manchester, UK
| | - Stefano Mariani
- School of Environment and Life Sciences, University of Salford, Greater Manchester, UK
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Shephard S, Gerritsen H, Kaiser MJ, Reid DG. Spatial heterogeneity in fishing creates de facto refugia for endangered Celtic Sea elasmobranchs. PLoS One 2012; 7:e49307. [PMID: 23166635 PMCID: PMC3498144 DOI: 10.1371/journal.pone.0049307] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 10/08/2012] [Indexed: 11/18/2022] Open
Abstract
The life history characteristics of some elasmobranchs make them particularly vulnerable to fishing mortality; about a third of all species are listed by the IUCN as Threatened or Near Threatened. Marine Protected Areas (MPAs) have been suggested as a tool for conservation of elasmobranchs, but they are likely to be effective only if such populations respond to fishing impacts at spatial-scales corresponding to MPA size. Using the example of the Celtic Sea, we modelled elasmobranch biomass (kg h(-1)) in fisheries-independent survey hauls as a function of environmental variables and 'local' (within 20 km radius) fishing effort (h y(-1)) recorded from Vessel Monitoring Systems data. Model selection using AIC suggested strongest support for linear mixed effects models in which the variables (i) fishing effort, (ii) geographic location and (iii) demersal fish assemblage had approximately equal importance in explaining elasmobranch biomass. In the eastern Celtic Sea, sampling sites that occurred in the lowest 10% of the observed fishing effort range recorded 10 species of elasmobranch including the critically endangered Dipturus spp. The most intensely fished 10% of sites had only three elasmobranch species, with two IUCN listed as Least Concern. Our results suggest that stable spatial heterogeneity in fishing effort creates de facto refugia for elasmobranchs in the Celtic Sea. However, changes in the present fisheries management regime could impair the refuge effect by changing fisher's behaviour and displacing effort into these areas.
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Affiliation(s)
- Samuel Shephard
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland.
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Silva JF, Ellis JR, Catchpole TL. Species composition of skates (Rajidae) in commercial fisheries around the British Isles and their discarding patterns. JOURNAL OF FISH BIOLOGY 2012; 80:1678-1703. [PMID: 22497403 DOI: 10.1111/j.1095-8649.2012.03247.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent regulations have required European nations to report commercial landings of Rajidae (skates) to species level since 2008. Morphological similarities between some species, variability in colouration and regional differences in common names may compromise the accuracy of some of these data. An increased proportion of rajid landings reported by the U.K. (England, Wales and Northern Ireland) are now reported to species level (42% in 2008, rising to 92% in 2010). Recent landings (2007-2010) of Rajidae by the U.K. indicated that the majority of reported landings were made by otter trawl (55·9%), tangle and gillnet (18·7%) and beam trawl (15·5%). Approximately 70% of recent landings originated from four ICES Divisions: the Irish Sea (VIIa), western English Channel (VIIe), Bristol Channel (VIIf) and southern North Sea (IVc). Recent species-specific landings of Rajidae are appraised in terms of the species reported and the overall composition, and potential problems identified. Data from observer trips have been used to estimate the species composition of Rajidae taken in some of the main commercial fisheries operating around the British Isles, and these data are compared to landings. Although there was typically broad agreement between these data sets in terms of the main species landed, misidentification issues were apparent and Rajidae with highly patchy distributions may be under-represented in observer data. Data from observer trips were also used to examine the discard and retention pattern. Most rajid species were first retained from total lengths, L(T) , of 27-34 cm, with 50% retention occurring at between 49 and 51 cm and near-full retention at L(T) of 60-67 cm. Beam trawls captured a higher proportion of smaller individuals, whilst gillnets (>150 mm mesh size) caught proportionally more larger rajids.
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Affiliation(s)
- J F Silva
- Centre for Environment, Fisheries and Aquaculture Science-CEFAS, Lowestoft Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, UK.
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Ellis JR, McCully SR, Brown MJ. An overview of the biology and status of undulate ray Raja undulata in the north-east Atlantic Ocean. JOURNAL OF FISH BIOLOGY 2012; 80:1057-1074. [PMID: 22497373 DOI: 10.1111/j.1095-8649.2011.03211.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The undulate ray Raja undulata is one of the lesser-known skates occurring on the continental shelf of the north-east Atlantic Ocean. It is patchily distributed throughout its range, with sites of local abundance in the central English Channel and off the coasts of Ireland, France, Spain and Portugal. Raja undulata is most abundant in coastal waters (<50 m deep) and is often found in proximity to large estuaries, rias and bays. It is a relatively large-bodied species, attaining a maximum total length (L(T) ) of at least 114 cm, with females maturing at an L(T) of c. 84 cm in Portuguese waters. Although infrequently taken in existing trawl surveys, it can be locally abundant in certain areas, where it can be the dominant skate species. Given its large size, patchy distribution and concern over the possibilities of localized depletions, the IUCN listed R. undulata as an endangered species and, since 2009, the European Union has established regulations to prohibit commercial fisheries landing the species. Given the increased interest in the species, a synopsis of current knowledge is provided, and available data from internationally co-ordinated trawl surveys presented.
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Affiliation(s)
- J R Ellis
- Centre for Environment, Fisheries and Aquaculture Science-CEFAS, Lowestoft Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, UK.
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Farrell ED, Mariani S, Clarke MW. Reproductive biology of the starry smooth-hound shark Mustelus asterias: geographic variation and implications for sustainable exploitation. JOURNAL OF FISH BIOLOGY 2010; 77:1505-1525. [PMID: 21078015 DOI: 10.1111/j.1095-8649.2010.02771.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Examination of the reproductive biology of Mustelus asterias in the north-east Atlantic Ocean highlighted apparent geographical variation in maturity, fecundity and ovarian cycle between Atlantic and Mediterranean populations. The stretch total length (L(ST) ) and age at 50% maturity for Atlantic males and females were estimated at 78 cm L(ST) and 4-5 years and 87 cm L(ST) and 6 years, respectively. Size at maturity of females was considerably smaller than in Mediterranean specimens (96 cm L(ST) ). Ovarian fecundity ranged from eight to 27 oocytes and uterine fecundity from six to 18 embryos. The gestation period was c. 12 months, followed by a resting period of c. 12 months, resulting in a biennial cycle. Females stored sperm in the oviducal gland and, unlike Mediterranean specimens, no uterine compartments were observed in Atlantic specimens. This study reveals the existence of strong, possibly adaptive, divergence in life-history traits in an elasmobranch, whose northern populations may be more susceptible to overexploitation than previously believed.
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Affiliation(s)
- E D Farrell
- Marine Biodiversity, Ecology & Evolution, School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
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