Many freshwater ecosystems suffer from dense common carp (Cyprinus carpio L.) stocks. From the ecological point of view, high carp densities are not desirable because of several negative impacts (e.g. bioturbation, competition with other benthivores). A mail and internet survey among specialised carp anglers (SCAs) (n = 710) suggests that, in Germany, carp anglers' catch exceeds commercial carp harvest by up to 2500%. This indicates that by following at least five steps (marketing, education, specific regulations, risk communication and monitoring), carp angling may reduce carp stocks efficiently. Moreover, demographics, participation patterns, economic impact and value of SCAs suggest a great potential for marketing (tourism, commercial fishermen). Thus, specialised carp angling provides a means for inland (carp) fisheries management world-wide. However, input-output balances for total phosphorus revealed that, under certain conditions, carp angling may contribute substantially to anthropogenic eutrophication if ground- and pre-baiting is used in excess and harvest rates are low. A simple equation was developed to provide managers with a tool for a quick appraisal of the likelihood of a negative ecological impact of phosphorus inputs by angling. Further research on this topic is recommended to develop management guidelines on maximum tolerable amounts of bait because ground-baiting is intensively practised not only by carp anglers but also by the general coarse fish angler. (C) 2002 Elsevier Science B.V. All rights reserved.
