Percorrer por autor "Bach, Pascal"
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- Distribution patterns and population structure of the blue shark (Prionace glauca) in the Atlantic and Indian OceansPublication . Coelho, Rui; Mejuto, Jaime; Domingo, Andrés; Yokawa, Kotaro; Liu, Kwang-Ming; Cortés, Enric; Romanov, Evgeny V.; da Silva, Charlene; Hazin, Fábio; Arocha, Freddy; Mwilima, Aldrin Masawbi; Bach, Pascal; Ortiz de Zárate, Victoria; Roche, William; Lino, Pedro G.; García-Cortés, Blanca; Ramos-Cartelle, Ana M.; Forselledo, Rodrigo; Mas, Federico; Ohshimo, Seiji; Courtney, Dean; Sabarros, Philippe S.; Perez, Bernardo; Wogerbauer, Ciara; Tsai, Wen-Pei; Carvalho, Felipe; Santos, Miguel N.The blue shark (Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheries from several nations in the Atlantic and Indian Oceans was compiled. Data sets included information on location, size and sex, in a total of 478,220 blue shark records collected between 1966 and 2014. Sizes ranged from 36 to 394 cm fork length. Considerable variability was observed in the size distribution by region and season in both oceans. Larger blue sharks tend to occur in equatorial and tropical regions, and smaller specimens in higher latitudes in temperate waters. Differences in sex ratios were also detected spatially and seasonally. Nursery areas in the Atlantic seem to occur in the temperate south‐east off South Africa and Namibia, in the south‐west off southern Brazil and Uruguay, and in the north‐east off the Iberian Peninsula and the Azores. Parturition may occur in the tropical north‐east off West Africa. In the Indian Ocean, nursery areas also seem to occur in temperate waters, especially in the south‐west Indian Ocean off South Africa, and in the south‐east off south‐western Australia. The distributional patterns presented in this study provide a better understanding of how blue sharks segregate by size and sex, spatially and temporally, and improve the scientific advice to help adopt more informed and efficient management and conservation measures for this cosmopolitan species.
- Diving into the vertical dimension of elasmobranch movement ecologyPublication . Andrzejaczek, Samantha; Lucas, Tim C. D.; Goodman, Maurice C.; Hussey, Nigel E.; Armstrong, Amelia J.; Carlisle, Aaron; Coffey, Daniel M.; Gleiss, Adrian C.; Huveneers, Charlie; Jacoby, David M. P.; Meekan, Mark G.; Daly, Ryan; Dewar, Heidi; Doherty, Philip D.; McAllister, Jaime D.; Domingo, Andrés; Dove, Alistair D. M.; Drew, Michael; Dudgeon, Christine L.; Duffy, Clinton A. J.; Elliott, Riley G.; Papastamtiou, Yannis P.; Ellis, Jim R.; Erdmann, Mark V.; Farrugia, Thomas J.; Ferreira, Luciana C.; McCully Phillips, Sophy R.; Ferretti, Francesco; Filmalter, John D.; Finucci, Brittany; Fischer, Chris; Fitzpatrick, Richard; Patterson, Toby A.; Forget, Fabien; Forsberg, Kerstin; Francis, Malcolm P.; Franks, Bryan R.; Gallagher, Austin J.; McGregor, Frazer; Galvan-Magana, Felipe; García, Mirta L.; Gaston, Troy F.; Gillanders, Bronwyn M.; Pierce, Simon J.; Gollock, Matthew J.; Green, Jonathan R.; Green, Sofia; Griffiths, Christopher A.; Hammerschlag, Neil; Hasan, Abdi; McMillan, Matthew N.; Hawkes, Lucy A.; Hazin, Fabio; Heard, Matthew; Peel, Lauren R.; Hearn, Alex; Hedges, Kevin J.; Henderson, Suzanne M.; Holdsworth, John; Holland, Kim N.; Howey, Lucy A.; Hueter, Robert E.; McNaughton, Lianne M.; Humphries, Nicholas E.; Hutchinson, Melanie; Queiroz, Nuno; Jaine, Fabrice R. A.; Jorgensen, Salvador J.; Kanive, Paul E.; Labaja, Jessica; Lana, Fernanda O.; Lassauce, Hugo; Lipscombe, Rebecca S.; Llewellyn, Fiona; Mendonça, Sibele A.; Macena, Bruno C. L.; Radford, Craig A.; Meyer, Carl G.; Meyers, Megan; Mohan, John A.; Mourier, Johann; Montgomery, John C.; Mucientes, Gonzalo; Musyl, Michael K.; Nasby-Lucas, Nicole; Natanson, Lisa J.; O’Sullivan, John B.; Richardson, Andy J.; Oliveira, Paulo; Richardson, Anthony J.; Righton, David; Rohner, Christoph A.; Brooks, Edward J.; Royer, Mark A.; Saunders, Ryan A.; Schaber, Matthias; Schallert, Robert J.; Abrantes, Kátya; Scholl, Michael C.; Seitz, Andrew C.; Semmens, Jayson M.; Setyawan, Edy; Shea, Brendan D.; Brown, Judith; Shidqi, Rafid A.; Shillinger, George L.; Shipley, Oliver N.; Shivji, Mahmood S.; Sianipar, Abraham B.; Afonso, André S.; Silva, Joana F.; Sims, David W.; Skomal, Gregory B.; Sousa, Lara L.; Burke, Patrick J.; Southall, Emily J.; Spaet, Julia L. Y.; Stehfest, Kilian M.; Stevens, Guy; Stewart, Joshua D.; Sulikowski, James A.; Ajemian, Matthew J.; Syakurachman, Ismail; Thorrold, Simon R.; Thums, Michele; Butcher, Paul; Tickler, David; Tolloti, Mariana T.; Townsend, Kathy A.; Travassos, Paulo; Tyminski, John P.; Vaudo, Jeremy J.; Veras, Drausio; Anderson, Brooke N.; Wantiez, Laurent; Weber, Sam B.; Castleton, Michael; Wells, R.J. David; Weng, Kevin C.; Wetherbee, Bradley M.; Williamson, Jane E.; Witt, Matthew J.; Wright, Serena; Zilliacus, Kelly; Block, Barbara A.; Anderson, Scot D.; Curnick, David J.; Chapple, Taylor K.; Araujo, Gonzalo; Armstrong, Asia O.; Bach, Pascal; Barnett, Adam; Bennett, Mike B.; Bezerra, Natalia A.; Bonfil, Ramon; Boustany, Andre M.; Bowlby, Heather D.; Branco, Ilka; Chateau, Olivier; Braun, Camrin D.; Clarke, Maurice; Coelho, Rui; Cortes, Enric; Mambrasar, Ronald; Couturier, Lydie I. E.; Cowley, Paul D.; Croll, Donald A.; Cuevas, Juan M.; Curtis, Tobey H.; Dagorn, Laurent; Dale, Jonathan J.Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements.
- Global habitat predictions to inform spatiotemporal fisheries management: initial steps within the frameworkPublication . Bowlby, Heather D.; Druon, Jean-Noël; Lopez, Jon; Juan-Jordá, Maria José; Carreón-Zapiain, María Teresa; Vandeperre, Frederic; Leone, Agostino; Finucci, Brittany; Sabarros, Philippe S.; Block, Barbara A.; Arrizabalaga, Haritz; Afonso, Pedro; Musyl, Michael K.; Cortés, Enric; Cardoso, Luis Gustavo; Mourato, Bruno; Queiroz, Nuno; Fontes, Jorge; Abascal, Francisco J.; Zanzi, Antonella; Hazin, Humberto Gomes; Bach, Pascal; Sims, David W.; Travassos, Paulo; Coelho, RuiTuna Regional Fishery Management Organizations (tRFMOs) are increasingly interested in spatiotemporal management as a tool to reduce interaction rates with vulnerable species. We use blue shark ( Prionace glauca ) as a case study to demonstrate the critical first steps in the implementation process, highlighting how predictions of global habitat for vulnerable life stages can be transformed into a publicly -accessible spatial bycatch mitigation tool. By providing examples of possible management goals and an associated threshold to identify essential habitats, we show how these key areas can represent a relatively low percentage of oceanic area on a monthly basis (16-24% between 50 degrees S and 60 degrees N), yet can have relatively high potential protection efficiency (similar to 42%) for vulnerable stages if fishing effort is redistributed elsewhere. While spatiotemporal management has demonstrable potential for blue sharks to effectively mitigate fishing mortality on sensitive life stages, we identify inherent challenges and sequential steps that require careful consideration by tRFMOs as work proceeds. We also discuss how our single-species framework could be easily extended to a multispecies approach by assigning relative conservation risk before layering habitat model predictions in an integrated analysis. Such broader application of our approach could address the goals of tRFMOs related to reducing the ecosystem effects of fishing and pave the way for efficient fisheries co-management using an ecosystem-based approach.
- Global-scale environmental niche and habitat of blue shark (Prionace glauca) by size and sex: a pivotal step to improving stock managementPublication . Druon, Jean-Noël; Campana, Steven; Vandeperre, Frederic; Hazin, Fábio H. V.; Bowlby, Heather; Coelho, Rui; Queiroz, Nuno; Serena, Fabrizio; Abascal, Francisco; Damalas, Dimitrios; Musyl, Michael; Lopez, Jon; Block, Barbara; Afonso, Pedro; Dewar, Heidi; Sabarros, Philippe S.; Finucci, Brittany; Zanzi, Antonella; Bach, Pascal; Senina, Inna; Garibaldi, Fulvio; Sims, David W.; Navarro, Joan; Cermeño, Pablo; Leone, Agostino; Diez, Guzmán; Zapiain, María Teresa Carreón; Deflorio, Michele; Romanov, Evgeny V.; Jung, Armelle; Lapinski, Matthieu; Francis, Malcolm P.; Hazin, Humberto; Travassos, PauloBlue shark (Prionace glauca) is amongst the most abundant shark species in international trade, however this highly migratory species has little effective management and the need for spatio-temporal strategies increases, possibly involving the most vulnerable stage or sex classes. We combined 265,595 blue shark observations (capture or satellite tag) with environmental data to present the first global-scale analysis of species' habitat preferences for five size and sex classes (small juveniles, large juvenile males and females, adult males and females). We leveraged the understanding of blue shark biotic environmental associations to develop two indicators of foraging location: productivity fronts in mesotrophic areas and mesopelagic micronekton in oligotrophic environments. Temperature (at surface and mixed layer depth plus 100 m) and sea surface height anomaly were used to exclude unsuitable abiotic environments. To capture the horizontal and vertical extent of thermal habitat for the blue shark, we defined the temperature niche relative to both sea surface temperature (SST) and the temperature 100 m below the mixed layer depth (Tmld+100). We show that the lifetime foraging niche incorporates highly diverse biotic and abiotic conditions: the blue shark tends to shift from mesotrophic and temperate surface waters during juvenile stages to more oligotrophic and warm surface waters for adults. However, low productivity limits all classes of blue shark habitat in the tropical western North Atlantic, and both low productivity and warm temperatures limit habitat in most of the equatorial Indian Ocean (except for the adult males) and tropical eastern Pacific. Large females tend to have greater habitat overlap with small juveniles than large males, more defined by temperature than productivity preferences. In particular, large juvenile females tend to extend their range into higher latitudes than large males, likely due to greater tolerance to relatively cold waters. Large juvenile and adult females also seem to avoid areas with intermediate SST (similar to 21.7-24.0 degrees C), resulting in separation from large males mostly in the tropical and temperate latitudes in the cold and warm seasons, respectively. The habitat requirements of sensitive size- and sex-specific stages to blue shark population dynamics are essential in management to improve conservation of this near-threatened species.
- Local indicators for global species: Pelagic sharks in the tropical northeast Atlantic, Cabo Verde islands regionPublication . Coelho, Rui; Macías, David; Ortiz de Urbina, Josetxu; Martins, Albertino; Monteiro, Carlos; Lino, Pedro G.; Rosa, Daniela; Casaca Santos, Catarina; Bach, Pascal; Murua, Hilario; Abaunza, Pablo; Santos, Miguel N.Pelagic sharks are an important bycatch in pelagic fisheries, especially for drifting longlines targeting swordfish. In the Cabo Verde Archipelago (tropical NE Atlantic), pelagic shark catches can reach a significant proportion of the total catches. Due to the increased concern on the status of pelagic shark species, this study was developed to enhance the current knowledge of those sharks in the Cabo Verde region in comparison to the adjacent areas, especially associated with European Union (EU) pelagic longline fishing activity. Stock status indicators for the two main species, blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus), were developed, based on fisheries data from logbooks and onboard scientific observers, including analysis of size frequency distributions and standardized catch-per-unit-of-effort (CPUE) indexes over time. The standardized CPUEs have been stable or increasing for both species in the past 10 years, indicating no signs of local depletion. In terms of sizes, the blue shark catch is composed mainly of adults, which can be a sign of a stable population. On the contrary, the catch of shortfin mako is composed mainly of juveniles, which in conjunction of a decrease of mean size might be a cause of concern, highlighting possible overfishing on the species in the region. Thirty satellite tags, 25 archival miniPATs and 5 SPOT GPS, were deployed in the Cabo Verde Exclusive Economic Zone (EEZ), showing that those species are highly mobile. The biomass and size distributions were modeled with spatial and seasonal models (GAMs) identifying locations where juveniles are predominantly concentrated and that should be prioritized for conservation. This work presents new information on the status of pelagic sharks in the Cabo Verde region in the context of those highly migratory species, and can now be used to promote more sustainable fisheries in the region.
- Technical mitigation measures for sharks and rays in fisheries for tuna and tuna-like species: turning possibility into realityPublication . Poisson, François; Crespo, Francisco Abascal; Ellis, Jim R.; Chavance, Pierre; Bach, Pascal; Santos, Miguel. N.; Séret, Bernard; Korta, Maria; Coelho, Rui; Ariz, Javier; Murua, HilarioTuna fisheries have been identified as one of the major threats to populations of other marine vertebrates, including sea turtles, sharks, seabirds and marine mammals. The development of technical mitigation measures (MM) in fisheries is part of the code of conduct for responsible fisheries. An in-depth analysis of the available literature regarding bycatch mitigation in tuna fisheries with special reference to elasmobranchs was undertaken. Studies highlighting promising MMs were reviewed for four tuna fisheries (longline, purse seine, driftnets and gillnet, and rod and line – including recreational fisheries). The advantages and disadvantages of different MMs are discussed and assessed based on current scientific knowledge. Current management measures for sharks and rays in tuna Regional Fishery Management Organizations (t-RFMOs) are presented. A review of relevant studies examining at-vessel and postrelease mortality of elasmobranch bycatch is provided. This review aims to help fisheries managers identify pragmatic solutions to reduce mortality on pelagic elasmobranchs (and other higher vertebrates) whilst minimizing impacts on catches of target tuna species. Recent research efforts have identified several effective MMs that, if endorsed by t-RFMOs, could reduce elasmobranchs mortality rate in international tropical purse seine tuna fisheries. In the case of longline fisheries, the number of operational effective MMs is very limited. Fisheries deploying driftnets in pelagic ecosystems are suspected to have a high elasmobranchs bycatch and their discard survival is uncertain, but no effective MMs have been field validated for these fisheries. The precautionary bans of such gear by the EU and by some t-RFMOs seem therefore appropriate. Recreational tuna fisheries should be accompanied by science-based support to reduce potential negative impacts on shark populations. Priorities for research and management are identified and discussed.