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bioRxiv · 10.1101/2024.01.29.577719

Lead in the head: persistent lead poisoning of waterfowl in the Camargue (southern France) ten years after the ban on the use of lead shot in wetlands

Bechet, A.·Olivier, A.·Cavallo, F.·Sauvajon, L.·Champagnon, J.·Defos-Durau, P.·Mondain-Monval, J.-Y.
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Abstract

Lead pollution remains a worldwide environmental and health issue with persistent detrimental effects on human and wildlife. Despite having been identified as an issue for wildlife a long time ago, the use of lead shot for hunting in wetlands was banned only in 2006 in France. Here, we took advantage of a long-term monitoring of waterfowl lead shot contamination in the Camargue (southern France) to (1) assess the local effectiveness of the French regulation in reducing waterfowl contamination and to (2) assess local compliance regarding the use of nontoxic shots in wetlands from 2007 onwards. We collected waterfowl gizzard from 38 hunters in the Camargue during 20 hunting seasons (1998 to 2017) for a total of 2306 gizzards from 28 different species. From 2008 to 2019, we also systematically collected the cartridge casings at three sites of communal wetland hunting. Ratio of lead vs nontoxic cartridges found in the field allowed monitoring hunter compliance with the new regulation. Despite a ten-year long ban on lead shot our results do not show any significant reduction in waterfowl exposure to lead through shot ingestion in the Camargue over the 20-year monitoring period. Indeed, gizzards of harvested waterfowl were as likely to contain at least one lead shot before the ban as after with a mean prevalence of 12% over the 13 species considered across the study period. Cartridge casings showed the persistence of use of lead shots by hunters in the Camargue wetlands despite a slow increase in the use of nontoxic cartridges. This unequivocally indicates that the law is far from being strictly applied, pointing to an insufficient policy enforcement. Our results support the need for a complete ban of lead ammunition for both wetland and terrestrial wildfowl which will facilitate policy enforcement and compliance.

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Bechet, A., Olivier, A., Cavallo, F., Sauvajon, L., Champagnon, J., Defos-Durau, P., Mondain-Monval, J.-Y.. 2024-01-31. Lead in the head: persistent lead poisoning of waterfowl in the Camargue (southern France) ten years after the ban on the use of lead shot in wetlands. https://doi.org/10.1101/2024.01.29.577719

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