Graduate student focuses study on smallmouth bass

Tyler McCroskey, a part-time fly-fishing guide, smiled as he delivered the unsettling briefing to the 20 anglers he’d invited to float the upper Spokane River.

“I have my fisheries scientist hat on today, so you can’t lie about the size of your fish,” he said, clarifying the main difference between fishing for fun and fishing for research.

“I have a ruler for lengths, a scale for weights down to the gram – and I write everything down.”

In a tribute to higher education, none of the anglers fled.

“We’re targeting smallmouth bass but I want to I.D. any other fish you catch,” he added.

“The rules are single- barbless hooks, wear your lifejacket, stay behind my raft, put fish you catch in our live wells and stop when I stop so we can tag fish.” McCroskey is wrapping up a summer field season for a biology master’s degree in fisheries science from Eastern Washington University.

He’s been scheduling electro-shocking surveys and sunset-to-3 a.m. snorkeling spotlight surveys around his jobs of guiding for Silver Bow Fly Shop and mixing drinks at a Spokane martini bar.

At the outset, the study aimed at more information about the river’s struggling native redband trout.

However, the 2015 drought, which led to extreme low flows and warm water conditions in the Spokane River and other streams, forced the 32-year-old graduate student to shift emphasis midstream to a related subject.

Smallmouth bass are a non-native predator that has established in the Spokane River after being introduced to Lake Coeur d’Alene, McCroskey said.

“To study redbands, you also have to know what’s going on with smallmouths,” he said. “This summer, the trout virtually disappeared from my upper-river study area. Water temperatures were up in the 80s. That’s lethal to trout, so if they didn’t go downstream to find cooler water, they were dead.”

The project is funded in part by Trout Unlimited. The research is coordinated with the Washington Department of Fish and Wildlife.

The state is planning a related project to install several habitat structures to provide better nursery areas for juvenile redband trout in the upper river near Starr Road.

“There’s good spawning gravel for trout in that area, but it’s near big cobble that’s good habitat for smallmouths,” McCroskey said.

The plan calls for locating the structures so they’re in the river in June when the newly hatched fish need them but above the river level as flows decline in summer and the water warms.

The structures should be designed to help trout without becoming a predator sink – a good place for the bass to ambush the trout, he said.

But because of the drought, instead of detailing redband trout in the 3.5 miles of river from the state line down to Harvard Road this summer, McCroskey is providing the state agency with a baseline on smallmouth bass.

“This is a once-in-50-years opportunity to get data on the fishery in these low-flow conditions,” he said, making lemonade from the lemons the weather delivered.

“This year is such an anomaly,” said Chuck Lee, Fish and Wildlife Department fisheries research biologist. “We’re glad to be getting this data. We’ll have to come back, maybe with another student, to get more data in a more normal year.

“We need the baseline information to compare with surveys after the structures are installed so we can evaluate their benefit to the trout.”

State fisheries staff joined McCroskey on some surveys this year.

“We saw adult redband in the upper river only on the first survey in early June,” Lee said. “The water temperature was already into the upper 60s. By July it was almost 80 degrees from surface water coming out of Lake Coeur d’Alene.”

The trout likely headed downstream below Sullivan Road for refuge in the cooler water that seeps into the river from the Spokane aquifer.

“The Spokane River loses water from Post Falls Dam downstream to about Sullivan,” Lee said. “We call the upper river from about Sullivan down the “gaining reach” because it has a cold-water influence from groundwater.”

Lee suggests that the trout moved downstream earlier than normal this year, but even that hypothesis will be evaluated.

“Some of the juvenile trout are probably eaten by the bass,” McCroskey said. “Eventually we want to know what percentage.”

State surveys over the years already have documented a boom in smallmouth bass and a decline in redband trout, he said.

“I’m getting the stomach contents of the smallmouth bass before we release them so we can analyze their diet.”

Bass in the upper Spokane feed a lot on fry early in the summer and then trend more to crayfish and invertebrates such as caddis flies.

McCroskey’s research will be tapping new DNA sampling technology to identify the species of fry the bass are eating. “They could be trout, long-nose dace, suckers and such,” McCroskey said.

“The (Fish and Wildlife) Department doesn’t have access to the DNA technology so that’s very interesting to us,” Lee said. “Fish decompose quickly in a smallmouth’s stomach during summer.”

EWU provided more than a few resources for the research project.

On this day in August, McCroskey had recruited students and faculty to join the Trout Unlimited volunteers for the hook-and-line sampling.

Some of the other graduate students are involved with research around the region, including mackinaw at Priest Lake, sticklebacks at Turnbull Wildlife Refuge and redbands in Lake Roosevelt.

The Spokane Riverkeeper had a boat in the fishing flotilla, as did Sean Visintainer of Silver Bow Fly Shop.

But the first crew to dial in to what the fish wanted was piloted by new assistant biology professor Paul Spruell. Margaret “Peggy” O’Connell, who chairs Eastern’s biology department, was hooking bass right and left, and when grad student Jessica Walston wasn’t netting fish for O’Connell, she was putting on a bass-catching clinic, too.

“Single curly-tail jig,” she said.

“It’s good to have some serious anglers on a research project,” McCroskey said, chiding student Tyler Janasz, who had yet to land a fish from the front of the lead research raft.

The anglers floated and cast through defined segments of the river. McCroskey timed them as they fished through the stretches, counted the fish caught and calculated catch per unit effort.

Before being released back in the river, McCroskey or one of his EWU helpers would measure and weigh each fish, scrape off a scale sample, and insert a water tube into its mouth to flush out a stomach content sample.

A spaghetti tag was inserted in the back of each bass and a pectoral fin was clipped if the fish had been recaptured during the summer.

More than 400 tagged smallmouths caught by hook and line were released back into the upper river this summer.

The buzz among the fly fishers indicated they had been catching smallies in calm-water areas of the upper river in August with topwater flies, including mouse patterns. They tempered their enthusiasm to make sure it didn’t sound like too much fun.

On this survey, most of them were stripping streamers to hook smallmouths.

“Some guys do want to come out and fish for the smallmouth and we’ll target them at certain times and places,” McCroskey said, referring to his guiding job with Silver Bow. “Smallmouth are a love-hate relationship for us. Catching them can be fun, but we’re also hoping to protect the native redband trout.”

Visintainer agreed, noting that smallmouth enthusiasts have prompted the fly-fishing industry to design rods and flies specifically for them.

“They’re a great gamefish and guides in some parts of the country are making a living fishing for them,” Visintainer said.

The average mature upper Spokane River smallmouth is around 10 inches long, but some have been caught up to 17 inches, McCroskey said.

Assuming that everything goes well with his research and he will successfully defend his thesis, McCroskey already is planning his next move.

“I’m hoping to celebrate with a trip to Belize for saltwater fly fishing,” he said. “I’ve always wanted to catch a tarpon!”

Visintainer chuckled. “He may be a scientist, but he’s still an angler.”