A novel push trap element to manage carp (Cyprinus carpio L.): a laboratory trial

Abstract

Common carp (Cyprinus carpio L.) cause detrimental changes to aquatic ecosystems and are a declared pest fish in several countries. Despite existing management options, the development of new technologies is desirable as the range of the common carp is predicted to expand and their eventual control will rely on an integrated approach. The present paper describes a laboratory trial of a novel ‘finger style’ push trap element designed to catch carp ≥250 mm total length (TL). Forty-five adult carp (mean length: 603.0 ± 74.9 mm s.d. TL) were placed into the downstream section of a 7.25-m flume and exposed to three stimuli (water level manipulation, flow and light) to encourage upstream movement towards the push trap element. Forty-one carp (91.1%) pushed through the trap element over 16 h and none escaped. Only an average of ~5% of carp’s known pushing capacity was needed to push through the ‘fingers’ and enter the trap, and modelling suggested that a 250-mm TL carp would need to exert ~22% of its pushing capacity. The results confirm that the push trap element design is matched to the morphology and ecology of carp and, pending field validation trials, promises success as a novel management option.