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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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Humans and scavenging raptors facilitate Argentine ant invasion in Doñana National Park

Humans and scavenging raptors facilitate Argentine ant invasion in Doñana National Park

Biotic resistance by native communities could have a role in the spread of invasive species. Native communities with higher species richness should be less susceptible to invasion by exotic species than those with fewer component species, interspecific interactions acting as biotic barriers by creating a highly competitive environment. This seems to be the case in the invasion of the Argentine ant, Linepithema humile, but only when the environment is unfavorable for the survival of the invader. The progress of Argentine ant invasion through favorable and unfavorable habitats of Doñana National Park was studied across three temporal snapshots covering three decades (1992, 2000, 2016). Biotic resistance of the native community was assessed using species richness, as well as dominance and community structure. The role of abiotic factors (quality of surrounding habitat and spatial variables) and of potential vectors of Argentine ant dispersal across unfavorable areas was also explored. No evidence of biotic resistance was found. On the contrary, invasion proceeded from trees with higher ant species richness, probably because those trees are larger and provide more resources and better protection from aridity. Furthermore, evidence was found that the invasion of new trees across a matrix of unfavorable habitat could be influenced not only by humans, but also by scavenging avian predators, which could act as vectors of ant dispersal through transport of carrion also exploited by the ants. Such leapfrog expansion through mobile predators could represent an overlooked mechanism that would enrich our understanding of invasion dynamics and provide potential opportunities for management of invasive species. informacion[at] Castro-Cobo et al (2019) Humans and scavenging raptors facilitate Argentine ant invasion in Doñana National Park: no counter-effect of biotic resistance. Biol Invasions 21:2221–2232. Doi 10.1007/s10530-019-01971-5