Researchers will be combing 15 streams to determine the impact contaminants are having on resident fish. ThinkStock.com
Grand Valley State University researchers Rick Rediske and James O’Keefe will partner with a team of researchers from the University of Notre Dame on a two-year study examining how variables in watershed landscapes impact contaminant levels in stream resident fish.
“We are looking at 15 tributaries of Lake Michigan,” said Rediske, a professor of water resources at GVSU’s Annis Water Resources Institute. “We want to determine whether salmon migration is carrying PCBs (and other contaminants) into native trout streams.
“When the salmon run upstream to spawn, they die and their carcasses decay, and whatever contaminants they are carrying at that time are released into the stream. We want to look into that process.
“Some streams have very large salmon runs and the banks are literally littered with fish in the fall. We want to get a handle on how much contaminants are being transferred by that means. We are looking at streams that have open access — are open to salmon runs. And then there are other ones that have barriers — either dams or electric barriers for lamprey — and those are our control sites.”
Rediske said the issue of contaminant transfer is particularly important as scientists and fishery managers consider returning waterways to a more natural state by removing dams.
“That is a big emphasis: opening up streams to fish passage,” he said.
Rediske said salmon were chosen for the study because of their spawning patterns, their lifespan and their size.
“Salmon live a long time, they are a large fish, and they accumulate chemicals like PCBs, DDT and flame retardant. They also run upstream in large numbers,” Rediske said.
A preliminary study already has been conducted and indicated some fairly high levels of contaminants are being transferred, he said.
“This project is taking it one step further,” Rediske explained. “We want to look at what watershed characteristics influence the process of the contaminant transfer. Obviously, if the watershed flushes out fast, there may not be as much impact. Certain aspects of the watershed might allow the contaminants to be retained better, so we are looking at what watershed characteristics influence that.”
Public health also is an important factor of the study. The researchers are working specifically with some Native American tribes because Rediske said they have a greater stake in the fisheries.
“There are fishing advisories, and this is something to consider when you develop fishing advisories,” he said. “This is one of the reasons why we are working with some of the Native American tribes: They consume more fish than the general population. If they are fishing in a native trout stream without the salmon runs, they are getting lower levels than if the salmon were allowed to migrate up there.”
Rediske called the types of contaminants the salmon are carrying “legacy” contaminants — deposited into waterways by industrial activity in the 1950s, ’60s and ’70s.
“It takes generations for the contaminants to filter out or to be essentially diluted out,” he said.
During the first year of the project the researchers will collect and analyze the fish; in the second year they will concentrate on using the data to develop a usable model for scientists and fishery managers, and also will do educational outreach around the findings.
Rediske is hoping additional phases might follow, specifically focusing on public health and climate change impacts on contaminants.
The study is being funded by a $222,115 grant from the Great Lakes Fishery Trust.