Action: American bullfrog control: Biological control using native predators
- One replicated, controlled study conducted in Belgium found the introduction of the northern pike led to a strong decline in bullfrog tadpole numbers.
Introduction of native predators can increase predation on bullfrog tadpoles, thereby biologically controlling bullfrog populations.
Supporting evidence from individual studies
One replicated, controlled study conducted from 2007 to 2009 in Balen, north-eastern Belgium (Louette 2012) found the introduction of the northern pike Esox lucius led to a reduction in bullfrog tadpole biomass with time, which was not significant overall, but highly significant from Spring year two. In year two, tadpole biomass in ponds with introduced pike reached only a tenth of their biomass in control (unmanaged) treatments in year two. No effect of draining was observed. Four treatments were randomly assigned to twelve ponds. The control included two replicates with no draining and no pike. The second treatment included four replicates of pike, but no draining. . The third included three replicates of draining and no introduction of pike. The fourth included three replicates of pike and draining. Draining was performed in June 2007, with removal of all amphibians and fish. Juvenile pike were introduced in May 2008 and 2009.