Ecotoxicological effects of soft plastic fishing lures on the benthic amphipod Hyalella azteca

Plastic pollution by lost, abandoned and discarded commercial fishing gear is well characterized for marine systems, whereas the environmental impact of lost recreational fishing gear in freshwater systems remains unclear. Especially soft plastic lures are increasingly used, potentially contributing to the pollution of waterbodies by the release of hazardous substances such as plasticizers. The objective of this study was to compare water- and sediment-borne acute toxicity of three types of commonly used soft plastic lures with the benthic amphipod Hyalella azteca. A standardized test setup was used to compare 96 h water-only and sediment acute toxicity as well as 14 d toxicity to determine leachate effects in a dilution series. Chemical composition of the lures and leachates in the water were qualitatively analyzed. All of the three tested soft lures - including those claiming to be environmentally friendly - consisted of PVC and contained plasticizers, including highly concerning substances such as diethylhexyl-phthalate and dibutyl-phthalate, as well as other additives. Depending on tested lure type, even dilutions of the leachate to 1.5 % were highly toxic and caused up to 100 % mortality in H. azteca after 96 h exposures, especially in treatments without sediment. Strong differences in the chemical composition and resulting ecotoxicological effects among different lure types were identified. The results of this study demonstrate that the currently underestimated effects of soft plastic fishing lures require better documentation, awareness and regulation to reduce environmental pollution by recreational angling.