HELENA — Chances are, if you had a “trout on” while fishing on the Missouri River between Helena and Great Falls recently, it was a nice sized one.
Fish surveys by Montana Fish, Wildlife and Parks this year revealed that rainbow and brown trout numbers remain above the long-term average in the Missouri River between Holter Dam and the town of Cascade, according to Grant Grisak, a state fisheries biologist. And while the numbers haven’t been crunched upstream, FWP biologist Eric Roberts said they were finding a lot of fish and that they’re pretty good size.
“This year we did (the fish survey) below Hauser Dam, and while the number of fish may have dropped a little bit, the size of the fish was noticeably larger for both rainbow and brown trout,” Roberts said. “The average size of fish was in the four-pound range, and that’s about the middle; so we handled quite a bit of fish that were bigger than that.”
Roberts noted that he alternates each year between surveys below Hauser and Holter dams.
Downstream near the town of Craig, state fisheries crews estimated the Missouri River held 5,194 rainbow trout that were greater than 10 inches long per mile. That’s not quite as many as in previous years —6,034 per mile in 2011 and 7,312 in 2012 — but it surpasses the long-term average of 3,174 rainbows per mile.
Grisak, who works that section of the Missouri above Craig and through Cascade, said he also was seeing fish larger than in previous years even though there were slightly fewer of them overall. He added that’s typical when the population reaches its maximum size.
“This year, 87 percent of the rainbow trout in the Craig section were 15 inches long or greater, and 35 percent of the population was 18 inches long or longer,” Grisak said in a press release.
Farther downstream near Cascade, the estimated number of rainbow trout that were 10 inches long and greater was 2,260 per mile, above the long-term average of 1,551 per mile.
Grisak anticipates that the population should return to normal levels next year, unless an unusually large flush of water comes through the spawning tributaries. High water in the Missouri River tributaries typically equates to high rainbow trout production, according to Grisak.
Brown trout in the Craig section that were 10 inches long and greater were estimated at 745 per mile. The long-term average is 578. Brown trout in the Cascade section that were 10 inches long and greater were estimated at 447 per mile, with the long-term average there at 387.
Brown trout populations are sampled in the spring and rainbow populations are sampled in the fall.
Aren Lindquist, who works in The Trout Shop in Craig, said there’s definitely a lot more trout in the river, which also translates to more people fishing there.
“It doesn’t matter if it’s rainbows or browns. But since the majority out there are rainbows, that’s what they catch; brown trout are a little more tricky,” Lindquist said. “People come out because of the characteristics of the Missouri. Its tail waters are pretty consistent water temperature and the fish have an abundant food source.”
Roberts said the popularity of the Missouri River fishery obviously hasn’t negatively impacted the trout population, with many anglers practicing catch and release techniques.
But that same popularity has led to some grumbling among the various fishing factions.
“From a social perspective, there is some friction there,” Roberts said. “You have more folks in jet boats, then you have the boaters and the waders, and each one wants to blame the other for perceived changes to the fishery. The waders say the boaters are dragging their anchors through the spawning redds (nests) and the boaters say the waders are going through the redds.
“But from a biological perspective, things are cooking along pretty good out there.”