Big Sky Outdoor News & Adventure

Missouri River Trout Populations Up – MFWP
Fisheries surveys this year indicate rainbow and brown trout numbers are up in the Missouri River between Holter Dam and Cascade.
State biologists this fall found 3,458 rainbow trout greater than 10 inches long near the town of Craig on the Missouri. The long-term average for that section is 2,917.
“The rainbows in the Craig section were remarkably high quality,” says Grant Grisak, Fish Wildlife and Parks fisheries biologist. “About 85% of the rainbows were 15 inches and larger, and fish in the 18 inch length group alone represented 24% of the total population.”
The largest rainbow sampled was 4.8 pounds.
In the Pelican Point
section, just upstream from the town of Cascade, rainbows were estimated at 1,577 per mile, which is higher
than the long-term average of 1,494.
Grisak said: “64% of the
rainbows in the population were
15 inches and larger.”
Brown trout populations in
the river were also up. The spring estimate of brown trout in the Craig section was 584 per mile in the Craig section; 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.
Brown trout populations are sampled in the spring and rainbow populations are sampled in the fall.
During late summer and early fall, Missouri River anglers reported good fly-fishing for larger rainbows, which Grisak says, is consistent
with the number of large rainbows observed during the population
estimates.
Anglers also reported many brown trout in the Craig section, which is likely a result of unusually cooler weather in early October causing browns to swim upstream and start their spawning run about a month earlier than normal, said Grisak.