Evolution of the sea lamprey control barrier program: The importance of lowermost barriers

Abstract

Sea lamprey control has effectively reduced sea lamprey populations by 90% in the Laurentian Great Lakes. The success of the program is directly tied to the presence of lowermost barriers on tributaries that prevent sea lamprey access to spawning and rearing habitats, and thus limit the size and scope of applications of lamprey-specific pesticides (lampricides). However, a complete inventory of these barriers has never been compiled nor have they been prioritized. Here, we identified 494 lowermost barriers that block sea lamprey from accessing 51,434 km of upstream rearing habitat, saving the control program up to $17,442,477 per year in deferred lampricide applications. Many of these barriers are nearing or past their intended life expectancy and the call for barrier removal will continue as demands for public safety, flood control, cost of repairs, fish passage, and recreation increase. The barriers highlighted in this paper represent the first step towards developing a prioritized list to direct control program infrastructure investment and for fishery managers to identify areas conducive for habitat restoration. Ensuring that the control program can rely on an effective barrier program in the future will require negotiation with stakeholders, new technologies that make barriers safer, more efficient, and fish passage friendly, public engagement for the barrier program, and increased funding and investment in prioritized lowermost barriers.