Newly developed exit options for European otters from fish fykes

Abstract

Entrapment and subsequent drowning in fish fykes poses an anthropogenic mortality hazard to Eurasian otters (Lutra lutra). Different concepts on how to solve this problem have been debated in the past. To proactively prevent future fatal interactions and increase acceptance among fishers, this study tested two exit mechanisms for otters to safely escape from fyke nets, while still retaining full trap functionality for inland fisheries. Both exit options, a tearable latex lacing around flexible metal wires (100% success rate, n = 6) and a steel hoop-spring construction (90%, n = 10) were successfully tested in 16 otter escape trials and 30 additional tests for fish (pike, eel, and common bream) retention (100%). The results indicate that the modifications of the fish traps were effective for otter conservation and commercial fisheries. Thus, both options can be recommended as equally good otter protection measures for fyke-net fisheries of the tested type and similar sizes. However, these data were yielded under controlled conditions and it is possible that field results could differ. Hence, the presented results should be additionally verified under field conditions.