Managing invasive vertebrates in riverscapes via geomorphic and life history bottlenecks

The Eel has been invaded by two aquatic vertebrates of special conservation and fisheries concern. Sacramento pikeminnow, introduced in the late 1970s to Lake Pillsbury, have spread throughout the watershed and threaten native salmonids, via predation (by larger pikeminnow) and competition for food (with smaller pikeminnow). Threats from pikeminnow are expected to worsen as the river warms (Georgakakos 2020, Georgakakos et al., in preparation). In addition, invasive bullfrogs threaten native frogs as well as an array of other native vertebrates, via predation by adult bullfrogs as well as adverse effects of bullfrog on native tadpoles (Kupferberg 1997). With support to Mary Power and Sarah Kupferberg from the Ca. Dept. of Fish and Wildlife, and in collaboration with CalTrout, CDFW, Stillwater Sciences, Inc., and the Eel River Recovery Project, we are investigating how bullfrogs and pikeminnow could best be managed during critical bottlenecks of their life histories, as they move through or reside in habitat ‘bottlenecks’ along the riverscape.