HELENA — The Missouri River’s reputation as a world-class fly-fishing destination got a boost Monday with the release of a report that populations of large trout continue to climb in the blue-ribbon fishery.For the second consecutive year, the Montana Department of Fish, Wildlife & Parks fisheries survey on the Missouri found that the number of large rainbow and brown trout between Holter Dam and Cascade are up.
State biologists this fall found 3,458 rainbow trout longer than 10 inches near Craig. The long-term average of rainbows that size for that section is 2,917.
“The rainbows in the Craig section were remarkably high quality,” said Grant Grisak, FWP fisheries biologist. “About 85 percent of the rainbows were 15 inches and larger, and fish in the 18-inch length group alone represented 24 percent of the total population.”
The largest rainbow sampled was 4.8 pounds.
In the Pelican Point section of the river, just upstream from Cascade, rainbow trout were estimated at 1,577 fish per mile, which is higher than the long-term average of 1,494 rainbows per mile.
According to Grisak, 64 percent of the rainbows in the population were at least 15 inches long.
Brown trout populations in the river also are up. The spring estimate of brown trout in the Craig section was 584 per mile; the long-term average there is 578. In the Pelican Point section, spring browns were estimated at 611 per mile — higher than the long-term average of 358.
The 2008 survey estimated there were 1,126 brown trout 10 inches and longer per mile, more than twice the 22-year average of 554 brown trout per mile.
Biologists don’t actually count all the fish in the river when they perform the survey. Instead, they electro-shock the water in an area, then count, tag and release the fish. Two weeks later, they repeat the process and use the ratio of tagged to untagged fish to calculate an estimate of the trout population per mile.
Brown trout populations are sampled in the spring and rainbow populations are sampled in the fall.
The report’s findings didn’t surprise 26-year Missouri River fishing guide Pete Cardinal, owner of Missouri River Angler in Craig.
“That’s what happens when you add water to a Montana river. The fish like it. There’s more habitat, more food, more space and greater survival,” Cardinal said. “It’s probably a real reflection of great habitat conditions from the last two years of great water levels.”
Trout numbers are healthy throughout the stretches of the river that were surveyed, according to FWP. Additionally, Missouri River anglers reported good fly-fishing for larger rainbows during the late summer and early fall.
Cardinal said he has been guiding on the Missouri since 1983, and he has never seen healthier looking fish than this season.
“The most noticeable difference is the quality of the fish. They’re just larger than they’ve been,” he said. “People are really happy with the quality of the fish, and the fish really fight hard. They’re so healthy that they just really tear you up when you hook them.”
Grisak said Cardinal’s observations are consistent with the number of large trout observed during the population survey.
The situation wasn’t as rosy on one of Montana’s other world-class rivers. According to FWP’s findings, trout population estimates in the Smith River show numbers continued to trend down over the long term.
In the Eagle Creek section of the Smith River — a couple miles downstream of Camp Baker — the number of rainbow trout longer than 8 inches was estimated at 371 per mile, which is consistent with a short-term trend, but below the long-term average of 527 such fish, Grisak said
Brown trout in the same section were estimated at 270 per mile, which is less than the long-term average of 315 fish per mile.
“Higher water flows and lower water temperatures in the Smith River this year should provide relief to future trout populations, especially in the wake of a nine-year drought experienced in central Montana,” Grisak said.
