Eradicating the invasive topmouth gudgeon, Pseudorasbora parva, from a recreational fishery in northern England

An established population of the invasive topmouth gudgeon, Pseudorasbora parva (Temminck & Schlegel), was discovered in a recreational fishery in Northwest England in 2002. As the lake was seasonally connected to a river catchment, providing potential for dispersal, a containment and eradication programme was initiated. Containment involved screening of outfalls and preventing fish movements off site. Eradication involved the fishery being treated twice with a rotenone‐based piscicide, in March and April 2005. The mean P. parva density prior to rotenone application was 6.1 m −2 ; following the application, none were recorded. Non‐target species in the fishery were removed prior to the application; following rotenone degradation, they were re‐introduced and subsequently spawned, with recording of young‐of‐the‐year. This contrasts with 2004 when only young‐of‐the‐year of P. parva were recorded. As the eradication appeared to be successful, the method is considered suitable for use on other populations posing a similar threat of dispersal of the species into rivers and on other invasive fish populations in undesirable locations.