Do Cormorants and Recreational Anglers Take Fish of the Same Species and Sizes?

Abstract

The Great Cormorant Phalacrocorax carbo is a widespread piscivorous waterbird. The competition for resources between recreational anglers and Cormorants has been causing serious conflicts between sport fisheries and environmentalists. This study aimed to compare fish catches by Cormorants and by recreational anglers in the upper Elbe River in Central Europe (Czech Republic). Cormorant diet was studied using regurgitated pellets, and catches of anglers were obtained from annual angling reports. Altogether 1478 Cormorant pellets were collected from which 6903 fish were measured and identified to species level. A total of 93,413 fish caught by anglers were identified to species level. Cormorant diet consisted of 24 fish species in six fish families. Cormorants caught smaller-sized fish (median mass 90 g) compared to fish caught by anglers (median mass 1700 g). The majority of fish caught by Cormorants were under the minimum legal catchable size for anglers. Species of moderate interest to anglers (mainly Roach Rutilus rutilus) dominated in Cormorant diets while Common Carp Cyprinus carpio dominated in catches of anglers. In conclusion, the direct competition for fish between anglers and Cormorants appeared low. However, as Cormorants consumed small fish that serve as prey for piscivorous fish species and that could potentially grow into legally sized fish for angling purposes, this still allows for indirect competition between Cormorants and sport fisheries.