The Crash of ’83

By Beacon Staff

Scientists are a conservative lot, generally given to phrases like “the data suggest” and “further research is needed.” So when I visited the Flathead Lake Biological Station to speak with Bonnie Ellis and Tom Bansak and heard them using terms like “kokanee crash” and “mysis explosion,” I was pretty sure I’d stumbled onto something big.

First a little background. The Bio Station, part of the University of Montana, is an internationally recognized scientific research and education facility located on the lake’s east shore at Yellow Bay. Founded in 1899, the station has an enviable collection of ecological data on our very significant freshwater lake. Dr. Bonnie Ellis, a research assistant professor, is in charge of the Flathead Lake Monitoring Program that began in 1977. Tom Bansak, a research scientist, was responsible for the installation of the station’s weather and water sensor network around the lake. The station maintains a website filled with useful information and real-time data from the sensor network at www.umt.edu/flbs.

I hadn’t gone looking for a big story. I’d heard Tom speak a while back, and when I invited myself down, Tom welcomed me to the facility and introduced me to Bonnie. In the course of initial small talk, I asked a relatively innocent question: Is your work here limited to observation, or do you do ecological interventions? And silence filled the air.

Then Bonnie spoke, “Our role is to provide long-term data and interpretations.”

Tom echoed, “We provide information, but it’s several state, federal, and tribal agencies that actually manage the lake.”

Bonnie provided detail. “There have been 19 deliberate introductions of non-native fishes into the lake, which began in the 1890s, along with shrimp, crayfish and plants.”

“And the net result has been a major shift in ecology from that of a Rocky Mountain lake to one of the Great Lakes,” Tom concluded.

OK, now they had my attention. Bonnie continued, “The most precipitous change was the kokanee crash of the 1980s. Kokanee, a popular game fish, was a non-native species introduced into the lake in the early 1900s. It established spawning sites, most notably at McDonald Creek, and its population grew. A whole ecology grew around its success, including a concentration of bald eagles and bears around the spawning sites, who fed on the kokanee.”

But, as the story continued, Montana Fish, Wildlife and Parks decided to help by introducing the Mysis shrimp, a species on which, it had been shown elsewhere, the kokanee would thrive. But lake ecology is complex. In Flathead Lake, the Mysis shrimp spent their days on the bottom of the lake. The kokanee, a daytime surface feeder, never knew the shrimp were there. However, the Mysis shrimp did eat the plankton that the kokanee would otherwise have eaten and were in turn eaten by the lake trout.

“The lake trout, predominantly native to the Great Lakes, is like a lake shark,” Tom noted. “It will eat almost anything.” Young lake trout found and began eating the Mysis shrimp on the bottom and thrived. But, as they grew into adulthood, they developed a preference for kokanee. So the kokanee got it from both ends. Their food supply was diminished and their predators were increased. In the course of three years during the mid 1980s, the kokanee went from the most popular and abundant game fish in the lake to nonexistent. “That’s what we mean by the kokanee crash,” Tom finished, “and the complexity of the species interactions and the extent of the trophic cascade (from algae to eagles) that occurred are what made this research significant and compelling to the scientific community.”

Maybe I’m just a sucker for a good fish story, but as I spoke with Tom and Bonnie about ecology, ecosystem management, and the complex computer simulations they run to predict ecological change, I realized that I’d just broken the surface. This research station (which includes classrooms, dormitories and a laboratory building that looks like the set of a CSI television series) is one of the must-visit sites in our area. A 15-mile drive south from Bigfork, the station welcomes the public and, in fact, has an open house planned for Thursday, July 25 from 1-5 p.m. Then you can learn about the lake while cruising on one of the station’s research vessels, see the facilities, and even ask what the scientists might know about the Flathead Monster.

Stay Connected with the Daily Roundup.

Sign up for our newsletter and get the best of the Beacon delivered every day to your inbox.