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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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Juvenile pheomelanin-based plumage colouration has evolved more frequently in carnivorous species

Juvenile pheomelanin-based plumage colouration has evolved more frequently in carnivorous species

Distinctive pheomelanin-based plumage colouration in juvenile birds has been proposed as a signal of immaturity to avoid aggression by older conspecifics, but recent findings suggest a detoxifying strategy. Pheomelanin synthesis implies the consumption of cysteine, a semi-essential amino acid that is necessary for the synthesis of the antioxidant glutathione (GSH) but that may be toxic if in excess in the diet. As the nestling stage probably represents a low stress period with limited requirement for GSH protection, the synthesis of pheomelanin in developing birds may help maintain cysteine homeostasis, particularly in species with a high content of protein in the diet (i.e. carnivores). Here this hypothesis was confirmed showing that, among 53 species of Western Palearctic birds, juvenile pheomelanin based colouration has evolved more frequently in strictly carnivorous species than in species with other diets. Understanding  the  physiological  mechanisms  of  colour  production  helps  to  explain  the  evolution  of  plumage  diversity. informacion[at]ebd.csic.es: Rodriguez-Martinez et al (2019) Juvenile pheomelanin?based plumage colouration has evolved more frequently in carnivorous species. IBIS DOI 10.1111/ibi.12770