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Impact of fisheries on sea turtles

The bycatch of sea turtles by industrial fisheries is receiving an increasing attention in recent years due to the high impact it causes on these endangered species. This issue was evaluated in southern Spain waters that harbors an important feeding ground of loggerhead and leatherback turtles, including the endangered Eastern Atlantic loggerhead population. To quantify the impact that different fisheries represents to sea turtles, 272 fishermen answered to detailed illustrated questionnaires in all the main ports of Andalusia and Murcia (Spain) during 2014. This study has updated the knowledge of turtle bycatch in the southwestern Mediterranean revealing a widespread impact of fisheries on sea turtles. Fishermen recognized an annual catch of 2.3 turtles per boat. Considering the census of industrial fishing boats in the study area (1182), more than 2840 sea turtles could be bycaught per year in the study area. Most of captures (96.2%) were produced during the summer. These results suggest a severe impact of most of legal fisheries (surface longline, pursue seine, trawling and small scale fisheries) on loggerhead feeding grounds in the southwestern Mediterranean. Fishermen suggests that drift fishing conducted by foreign or illegal fishermen and almadrabas are also causing a significant bycatch of turtles. Several measures such as reviewing compliance of current fishing and environmental regulations, modifying turtle technics to reduce turtle bycatch (e.g. reduction of the use of squid as bait and disposal of hooks deeper in the water column), facilitating the rescue and handle of wound turtles and their transport to the port for recovery, and recognizing the efforts of anglers to perform a more sustainable fishing, are recommended to mitigate this impact. informacion[at]ebd.csic.es: Marco et al (2020) Sea turtle bycatch by different types of fisheries in southern Spain. Basic and Applied Herpetology https://doi.org/10.11160/bah.187


http://ojs.herpetologica.org/index.php/bah/article/view/187
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Dwarfism in continental populations of natterjack toads in the absence of genetic isolation

Dwarfism in continental populations of natterjack toads in the absence of genetic isolation

Ample variation in body size is common in vertebrates over extensive geographical distances, or in isolated populations, where effective geographical barriers may cause dwarfism or gigantism. The potential causes of extreme size reduction in continental populations of amphibians within a short geographical distance and in the absence of geographical barriers were studied. Natterjack toads Epidalea calamita in Doñana National Park (Spain) experience up to 2.1?fold difference in body mass in as little as 37?km. Studying six populations divergent in body size, the genetic isolation of the dwarf populations using multilocus genotypes (16 microsatellites) was tested. Additionally, it was explored whether populations differed in trophic status (through stable isotope analysis), standard metabolic rate and growth pattern, senescence and age structure (conducting telomere length assays and skeletochronology). Advertisement calls were also recorded across populations and experimentally tested for behavioural reinforcement of the body size variation through female preferences. Local dwarfism in these populations occurs in the absence of genetic isolation while maintaining relatively high effective population sizes. Dwarf populations, however, were exposed to drier and warmer climatic conditions, have different trophic status, show lower mass?specific metabolic rate, and male advertisement calls with a higher dominant frequency. Juvenile growth differed among populations, reaching the adult stage at different body sizes. Altogether, these results suggest a significant influence of environmental conditions on the physiology and ecology of the Doñana E. calamita populations, mainly affecting toads between metamorphosis and sexual maturity. Further experimental and genomic studies focusing on these early life stages are necessary to dissect the relative roles of the environment and adaptive genetic differentiation on this phenomenon. informacion[at]ebd.csci.es: Hyeun-Ji et al (2020) Dwarfism in close continental amphibian populations despite lack of genetic isolation. OIKOS Doi 10.1111/oik.07086


https://onlinelibrary.wiley.com/doi/full/10.1111/oik.07086