Browsing by Author "Abascal, Francisco"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Challenges and opportunities in monitoring and mitigating sea turtle bycatch in tuna regional fisheries management organizationsPublication . Baéz, Jose Carlos; Domingo, Andrés; Murua, Hilario; Macías, David; Camiñas, Juan Antonio; Poisson, Francois; Jorda, María José Juan; López, Jon; Griffiths, Shane; Roman, Marlon; Hall, Martín; Gilman, Eric; Bruyn, Paul De; Swimmer, Yonat; Ceballos-Roa, Elvira; Wallace, Bryan; Coelho, Rui; Abascal, FranciscoFisheries that target tunas and tuna-like species are managed by tuna regional fisheries management organizations (t-RFMO) and are known to interact with various bycatch species, including sea turtles, with potentially negative effects. Actions and management measures implemented by t-RFMO to monitor sea turtle fisheries interactions, reduce their bycatch in fisheries, and carry out best practices for the handling and safe release of sea turtles, with the ultimate aim of improving the conservation of sea turtles are revised. Specifically, the actions and regulations for each of the following areas are revised: (i) data collection requirements, (ii) bycatch estimates and assessments, (iii) management measures, and (iv) any other conservation and management actions for sea turtle conservation. The particular case of the Mediterranean Sea also was analyzed, given that it has the highest rate of sea turtle bycatch in the world. Tuna-RFMO have a great potential for reducing fisheries bycatch impacts in marine turtle populations globally, but their actions are limited by their geographic scopes and mandates and the variety of habitats used by sea turtles during their life history. Tuna-RFMO also have a potentially significant role in leading the reduction of incidental sea turtle mortality in fisheries under their purview, both regionally and globally, by bringing together different stakeholders and initiatives.
- 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.