First test of a species-selective adult sea lamprey migration barrier

A species-specific, non-chemical method of preventing adult sea lamprey (Petromyzon marinus) passage into Great Lakes tributary streams is necessary to help reduce the population of this invasive fish species and prevent fragmentation of habitat of native fish species. We tested the effectiveness of a barrier in the form of a short angled (10° and 20°) wetted ramp in a lab and field setting. At the steeper angle, none of the ten adult sea lampreys tested achieved passage, although numerous attempts were observed. On the shallower ramp, 15-20% (3-4/20) of tested individual lampreys passed. We tested sample groups of nine native fish species and found varying rates of attempted and successful passage among these groups. More species and individuals succeeded in passing the 10° ramp. At least one individual from each of six species was able to pass the barrier: common sucker (Catostomus commersonii), hognose sucker (Hypentelium nigricans), creek chub (Semotilus atromaculatus), green sunfish (Lepomis cyanellus), smallmouth bass (Micropterus dolomieu), and golden shiner (Notemigonus crysoleucas). Only two of the individual walleyes (Sander vitreus) swam high enough to fully emerge from the downstream pool, with no successful passage. Although our sample sizes are not large enough to infer effectiveness of the selective ramp barrier at a species level, we conclude that inclined wetted ramps merit further investigation as a possible selective sea lamprey barrier.