The Effects of Pulse Pressure Water Gun Technology on Rusty Crayfish (Orconectes rusticus) and Round Goby (Neogobius melanostomus) Non-Native Egg Predators in Lake Michigan

Naturally reproducing populations of lake trout and cisco remain highly suppressed in Lake Michigan, and many conservation plans call for an improved understanding of mitigating factors impeding successful recruitment and implementation of conservation actions. Recovery of lake trout and cisco has suffered due, in part, to poor recruitment resulting from habitat degradation and egg predation from invasive species. Suitable spawning habitats (shallow coastal reefs) are rare and continue to be impacted by near shore hardening, excess nutrients, and anthropogenic changes to coastal sedimentary processes. In September 2013, we tested a 1966 cm³ chambered hydraulic water gun as a tool to suppress invasive rusty crayfish (Orconectes rusticus) and round goby (Neogobius melanostomus), two dominant non-native egg predators that impose a major limitation on native fish egg survival and recruitment. Rock bass (Amblopletis rupestris), a fish species possessing a gas bladder, were included as a positive control for the evaluation of the benthic goby, which lack a gas bladder. Sublethal responses such as effects to hearing organs were also added to select studies as traditional endpoints for lethal fish trauma assessments may no longer be feasible. Underwater acoustic information included amplitude data such as sound pressure levels, and cumulative sound energy levels.