Chapter 4: Biological impacts of recreational fishing resulting from exploitation, stocking and introduction

While the biological impacts of commercial fishing are well documented, those of recreational fisheries have received less attention. However, intensive and selective angling and related activities (e.g. fish stocking and introductions) can affect fish populations and aquatic ecosystems, often in conjunction with impacts external to the fishery. The risks range from those occuring to the exploited fish population (truncation of the natural age and size structure, delay of stock rebuilding through depensatory mechanisms, loss of genetic variability and adaptation, evolutionary changes) to those that occur to the aquatic ecosystem (changes in trophic cascades or nutrient cycling). In particular, genetic changes and the loss of biodiversity can be a severe threat to fish communities and ecosystems and require sophisticated management approaches. Finally, those implications for a sustainable management of recreational fisheries are discussed, which can help to reduce or avoid unwanted biological effects, social conflicts and ensure the long-term persistence of the natural resources.