Potential good news from the fight against bucket biologists.
Montana fishery biologists using something called “forensic geochemistry” have figured out the source and timeframe that walleye were moved into Swan Lake, in the state’s northwestern corner.
OTOLITHS, A BONE IN THE EAR OF FISH, CONTAINS CHEMICAL SIGNATURES THAT PROVIDES CLUES ABOUT WHERE THE ANIMAL CAME FROM. (OREGON STATE UNIVERSITY, FLICKR)
And genetic material from northern pike in Northeast Washington is pointing to a different source than the widely assumed one.
Whether or not the new tools help lead to arrests is a good question, but they will at least serve as a warning shot across the bow of those who would illicitly move fish around.
IN THE CASE OF THE WALLEYE, managers have concluded that at least two fish were driven over the continental divide on a 200-mile journey that occurred in the spring of 2015, according to a report in the Columbia Basin Bulletin last month.
“Our findings now allow investigators to look at fishing license sales, webcams, and boat registrations around the Lake Helena area for the time period when the walleye were illegally introduced,” Samuel Bourett, an FWP researcher, told the emailed newsletter.
The species is native to the Mississippi River and lower Missouri River basins, but as was common earlier last century walleye were moved westward for fishing opportunities.
Nowadays, the tide has turned against moving nonnative fish — or at least nonsterile ones — into new locations, though decades of population growth provide a ready reservoir for those who want to continue the practice.
But fishery officials are fighting back with increasingly sophisticated means.
In early 2016, several months after two walleye were gillnetted at Swan, Bourett’s agency and conservation groups offered a $30,000 reward for information on the illicit stocking of the lake, which provides critical habitat for Endangered Species Act-listed bull and cutthroat trout.
They also began examining the otoliths of the fish, looking for chemical signatures that could pinpoint where they came from.
In 2017 they built a database with fish from 13 popular Montana walleye waters.
Out of that they determined the origin of the Swan Lake release.
“Core to edge geochemical profiles of [two types of strontium] and (strontium/calcium) ratios in the walleye otoliths revealed that these fish had been introduced to Swan Lake within the past growing season, and their geochemical signature matched that of walleye sampled from Lake Helena, Montana, located 309 road kilometres away,” write Bourett and Niall Clancy in a paper recently published in the Canadian Journal of Fisheries and Aquatic Sciences.
Illegally stocking fish in Montana is punishable with fines running from $2,000 to $10,000, the loss of all license privileges and cleanup costs.
WDFW BIOLOGIST DANNY GARRETT SCOWLS WHILE HOLDING THE 13.5-POUND GRAVID HEN WALLEYE HE NETTED OUT OF LAKE WASHINGTON IN 2015. (DANNY GARRETT, WDFW)
Well to the west, in 2012 the otoliths of walleye from Lakes Roosevelt and Moses and Potholes and Scooteny Reservoirs were compared with those from Lake Washington fish for a common chemical signature but no match was found, according to state fisheries biologist Danny Garrett, who himself netted half a dozen more in 2015.
“I think there is merit in doing more of this work,” he notes.
THEY’RE NOT THE ONLY ONES TRACING where invasive fish are coming from. Dr. Kellie Carim works for the U.S. Forest Service’s National Genomics Center for Wildlife and Fish Conservation out of Missoula, and she’s looking into pike.
Another Upper Midwest transplant, northerns are also popular with fishermen but present a nightmare threat for Northwest salmon and steelhead managers as the species has crept its way down the Pend Oreille River and into Lake Roosevelt and is now at the mouth of the Spokane River, according to a recent story. Anecdotal reports from anglers put them further down, in Lake Rufus Woods.
With funding from a USDA Tribal College Initiative Grant, Carim has come to a rather interesting conclusion about where many of those pike actually originated.
“The history we’ve told ourselves, the simplest explanation, is that the fish are flowing downstream from Western Montana,” she says.
That is, from Noxon Reservoir, down the Clark Fork River into Idaho and through Lake Pend Oreille before arriving in Washington.
“However, what the genetic analysis says is that those in Lake Roosevelt and the Pend Oreille River are closely related to those in the Couer d’Alene drainage,” Carim says.
Rather than taking an aquatic highway, they most likely took a paved one, in a livewell up US 95 to I-90 to either Idaho 41 or US 2 to Washington 20 and the river.
From there, their population built and the theory has been that in high water years they were entrained out of the Pend Oreille into the Columbia River in British Columbia and then Lake Roosevelt.
DAVEY McKERN HOLDS ONE OF THE FIRST NORTHERN PIKE CAUGHT IN LAKE ROOSEVELT. THE SPECIES HAS BEEN LARGELY CONCENTRATED OFF THE MOUTHS OF THE KETTLE AND COLVILLE RIVERS, BUT SOME HAVE BEEN FOUND DOWNSTREAM AT THE MOUTH OF THE SPOKANE RIVER, ACCORDING TO A NORTHWEST POWER AND CONSERVATION COUNCIL REPORT. (DAVEY MCKERN)
Carim, whose work aims to identify where the pike are coming from to stop the flow into Eastern Washington, adds that DNA from other Upper Columbia and Pend Oreille fish aren’t in the database, meaning there are more potential sources out there too.
“We definitely need to collect more samples. Some fish are aren’t ‘assigning’ very well,” she says.
Next week, she will be presenting before the Northwest Power and Conservation Council on pike.
Meanwhile, state and tribal managers have been teaming up to take a hammer to the species.
According to a recent NWPCC article by John Harrison, 18,000 have been scooped out of the Pend Oreille River by the Kalispel Tribe and another 1,800 have been removed from Lake Roosevelt by the Colville and Spokane Tribes and WDFW. Anglers have also turned in more than 1,000 heads for cash through a Colville Tribes program. And hundreds of thousands of dollars are being spent to protect the investment of hundreds of millions of dollars put into salmon recovery in the Columbia Basin.
While bucket biologists will likely continue their illegal pike and walleye stockings, the odds are now increasing that someone will get caught.