Novel trophic subsidies from recreational angling transform the trophic ecology of freshwater fishes

Angling is a globally popular leisure activity. There are over 31 million anglers in Europe, many of which target species of the Cyprinidae family in lowland freshwater ecosystems using methods generally involving bait (e.g. groundbaits, seeds and pellets), with large bait inputs possible in periods of high angling activity. While these bait inputs act as novel trophic subsidies (‘angling subsidy’), substantial knowledge gaps remain on their influence on freshwater food-webs, including on fish trophic niche size and position. The effects of angling subsidies on the trophic ecology of cyprinid fish populations and their macroinvertebrate prey resources were investigated in field studies comparing waters of high angling activity (‘subsidised fisheries’) versus low angling activity (‘non-subsidised fisheries’), and complemented by a pond experiment using two cyprinid species in subsidy absence/presence. Methods were based on stable isotope analysis, with angling subsidies being δ13C enrich...