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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] Marco et al (2020) Sea turtle bycatch by different types of fisheries in southern Spain. Basic and Applied Herpetology
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Identified the main introduction routes of the red swamp crayfish Procambarus clarkii during its global-scale invasion

Identified the main introduction routes of the red swamp crayfish Procambarus clarkii during its global-scale invasion

This North American species is the most widely spread freshwater crayfish worldwide, and is one of the worst invasive species due to its severe impacts on the structure and functioning of freshwater ecosystems. The results of the study may help to prevent the further expansion of the red swamp crayfish and to avoid potential future invasions. The invasion routes followed by the red swamp crayfish during its human-driven expansion were reconstructed based on the analysis of a mitochondrial gene (COI), which was sequenced for 1,412 crayfish from 122 populations across the Northern Hemisphere. The article describes how different invasion scenarios have produced different genetic patterns among invasive populations. For example, in the US there are two main invasion routes, west- and east-wards from the native area. The invasive populations in the west are genetically more diverse, because they have received more introductions, which probably involved more individual crayfish, starting in the 1920s. The genetic results show that western US (California), itself an invaded area, was the source of the crayfish populations established in Hawaii and a probable source of the crayfish introduced to Japan, and from there to China, in the late 1920s. The low genetic diversity of all red swamp crayfish populations studied in Asia supports documentary evidence that a small group of some 20 individuals may have been the origin of the Japanese and Chinese red swamp crayfish populations which now number into the millions. The red swamp crayfish was introduced twice from Louisiana to south-western Spain, in 1973 (near the city of Badajoz) and 1974 (in the Guadalquivir River marshes). These introductions were promoted by the aristocrat Andrés Salvador de Habsburgo-Lorena. Until now, it has been assumed that these introductions were the sole origin of all red swamp crayfish populations established across Europe, but the new study finds evidence of a separate, later introduction. The large number of individuals involved in the two introduction events (around 500 in Badajoz and 6,000 in the Guadalquivir marshes) has led to the high genetic diversity levels observed in Iberian populations, although diversity values tend to be lower as populations are further away from the introduction foci. However, in this study a genetic profile in central-western Europe that is not present in the Iberian Peninsula was also unexpectedly detected, a finding that suggests that additional unrecorded introductions of the red swamp crayfish into Europe may have occurred, either from the US or from other invaded territories. información[at] Oficialdegui et al (2019) Unravelling the global invasion routes of a worldwide invader, the red swamp crayfish (Procambarus clarkii). Freshwater Biol