FWP biologist authors scientific paper on illegal fish introductions

KALISPELL - A Montana Fish, Wildlife & Parks biologist has identified an innovative approach to investigating illegal fish introductions and his research is being published in an international peer-reviewed scientific journal.

Sam Bourret, a fisheries biologist based out of FWP's Region 1 office in Kalispell, was the lead author of a manuscript titled, "Using forensic geochemistry via fish otoliths to investigate an illegal fish introduction."

The findings will be featured in the November edition of the Canadian Journal of Fisheries and Aquatic Sciences, which is published by the NRC Research Press, the largest scientific publisher in Canada with 24 journals distributed to over 125 countries. Niall G. Clancy, a graduate student at Utah State University, co-authored the paper with Bourret.

The paper is based on a study of the first suspected illegal introduction of walleye in Swan Lake in October of 2015. Using forensic geochemistry via fish otoliths, Bourret was able to trace the origin of the non-native walleye. The otoliths, which are the calcium carbonate structure in the inner ear bones of fish and contain unique identifying tracers, revealed that the walleye matched the geochemical signature of walleye from Lake Helena in central Montana. The research also identified that the walleye were introduced to Swan Lake sometime in the spring of 2015 and most likely have not established a population in Swan Lake.

Bourret's study marked the first use of otolith geochemistry as a forensic tool on a large scale. The information provides an important clue into the ongoing investigation of who illegally introduced the walleye. It also has far-reaching implications that could help inform invasive species management and monitoring.

"Our results highlight the utility of otolith geochemistry as a forensic tool, which has led to another study of a suspected illegal Northern Pike introduction in Lake Mary Ronan," Bourret said.

"We hope that by understanding more about illegal introductions and getting closer to making an arrest, our study will help curb future illegal fish introductions by notifying the public that FWP is serious about stopping the problem."

By publishing a manuscript in the NRC Research Press, Bourret's innovative research is now being shared with the world's scientific community as an important tool from a distinguished source.

Bourret graduated from the University of Idaho with a Master of Science degree in fisheries science in 2013. He joined FWP as a fisheries biologist in 2015.

"FWP biologists around the state provided otoliths used to identify the waterbody source of the introduced walleye. This type of coordination and information exchange is key to addressing broad scale management challenges like illegal fish introductions," said Matt Boyer, FWP Region 1 Science Program Supervisor.

Illegal introductions can have significantly negative impacts on lakes and rivers. They can often lead to lost recreational fishing opportunities, as well as collapsing ecosystems and altered food webs. Walleye are highly predacious and could impact the native bull trout population, as well as the kokanee salmon fishery in Swan Lake.

A reward up to $35,250 is available for information leading to the conviction of whomever is responsible for the illegal introduction. The state of Montana offers rewards up to $15,250 for information about illegal fish introductions. Montana Trout Unlimited has pledged a reward up to $20,000 for a tip that results in the conviction of the individual or individuals responsible for illegally introducing the walleye into Swan Lake.

Anyone with possible information on who introduced walleye into Swan Lake is encouraged to call 1-800-TIP MONT. Callers do not need to identify themselves and may be eligible for the cash reward.