Animal welfare implications of management strategies for invasive freshwater turtles

Invasive alien species are a recognised threat to biodiversity, ecosystem functions, and human well-being. Management efforts often prioritise ecological and economic outcomes, neglecting the implications of control methods on animal welfare. We investigated the perceived impacts on animal welfare of different lethal and non-lethal methods to control invasive slider turtles Trachemys scripta in Europe. We elicited the opinions of a group of 24 herpetologists, turtle caretakers, veterinarians and welfare experts, combining the Five Domains welfare framework with a formal structured elicitation approach. Experts generally agreed that welfare impacts in traps or transport would be mostly minor, but could increase with time of exposure, turtle densities and inadequate protocols. For captive containment post-capture, concerns included inadequate diets and habitats, disease and behavioural concerns, although the latter were particularly uncertain. For lethal methods, lethal injection and properly executed shooting were judged to cause no or mild suffering only. Self-expressed confidence in the elicited estimates was relatively high, but decreased for higher impact levels, longer timeframes and less-known welfare domains such as behavioural concerns. Future research would refine welfare assessment models, particularly for the evaluation of cumulative impacts across different methods and multiple affected individuals. However, in a field as multifaceted as animal welfare, some degree of expert interpretation will likely always be necessary to guide policy: structured expert elicitation can help formalise current knowledge and make those interpretations more transparent.