You Shall Not Pass!: Achieving Selective Fish Passage in the Presence of Invasive Species

The negative effects of instream barriers on ecosystem processes are well studied; particularly where they prevent the free passage of migratory fishes, and thus fragment populations of ecological or economic significance. However, in the Laurentian Great Lakes basin low-head barriers are commonly employed to prevent the wide-spread distribution of arguably its most harmful aquatic invasive species – sea lamprey (Petromyzon marinus), by preventing access to upstream reaches. This conflict (passage of desirable species vs. blockage of harmful invasives) necessitates a selective fish passage device capable of discriminating between multiple organisms simultaneously, which may be difficult to achieve if both groups exhibit similar body forms, behaviours or swimming abilities. The anguilliform body shape and climbing ability of lamprey may, however, allow for selective removal of the non-native pest, while allowing free passage of a wide range of other species. Here we will report findings from a proof-of-concept study employing a model selective fish passage device, incorporating a modified ‘eel ladder’ design and vertical slot channel while utilizing PIT-telemetry and infra-red video to examine passage ability and behaviour of three important species in the Great Lakes basin: sea lamprey, white sucker (Catostomus commersonii) and rainbow trout (Oncorhynchus mykiss).