Richard A. Erickson Kim T. Fredricks Nicholas M. Swyers Tyson Hatton Jon Amberg Aaron R. Cupp 2017 <p><span>Resource managers need for effective methods to prevent the movement of silver (<i>Hypophthalmichthys molitrix</i>) and bighead carp (<i>H. nobilis</i>) from the Mississippi River basin into the Laurentian Great Lakes. In this study, we evaluated dissolved carbon dioxide (CO₂) as a barrier and deterrent to silver (278 &plusmn; 30.5 mm) and bighead (212 &plusmn; 7.7 mm) carp movement in continuous-flow outdoor ponds. As a barrier, CO₂ significantly reduced upstream movement but was not 100% effective at blocking fish passage. As a deterrent, we observed a significant shift away from areas of high CO₂ relative to normal movement before and after injection. Carbon dioxide concentrations varied across the pond during injection and reached maximum concentrations of 74.5&plusmn;1.9 mg/L CO₂; 29 532 &ndash; 41 393 &micro;atm at the site of injection during three independent trials. We conclude that CO₂ altered silver and bighead carp movement in outdoor ponds and recommend further research to determine barrier effectiveness during field applications.</span></p> application/pdf 10.1139/cjfas-2015-0472 en NRC Research Press Responses of invasive silver and bighead carp to a carbon dioxide barrier in outdoor ponds article