Prognosis for trout numbers on Big Hole River 'not very good' says FWP biologist

big hole trout.jpg
Posted at 9:54 AM, Jun 02, 2023

BUTTE - The Big Hole River, like at Maiden Rock just south of Butte, is a paradise of fly fishing, but trout numbers in this waterway have been going down at an alarming rate in recent years and it has fish biologists and anglers very concerned.

“I’m very concerned. It’s because A, the whole population is low, and B, we have very few small fish. So, the prognosis for next year and the coming years is not very good,” said FWP Fish Biologist Jim Olsen.

Recent fish counts indicate the river between Jerry Creek Bridge and Browns Bridge shows a little less than 500 trout per mile. The river usually has between 900 and 1,100 brown trout and 350 to 400 rainbow trout.

“We’ve been monitoring the river since the late 60s as far as taking population estimates and right now we are as low as we’ve ever been before,” said Olsen.

Outfitters and anglers are concerned about the dropping fish numbers.

“It’d be frankly an economic collapse if this fishery went down and not just the Big Hole—it’s the whole Jefferson River Basin,” said Great Divide Outfitters owner Lia Jones in Divide.

Biologists are worried some sort of disease affecting fish could be one of the factors for the decline.

“Because we don’t understand exactly what's causing what’s going on, it’s very difficult to develop a management strategy to hopefully stop that and reverse that trend,” said Olsen.

Outfitters in the region have written a letter to the governor and state legislature demanding research into this issue.

“It takes science to figure this stuff out. There’s fish sitting in labs right now that need to be examined on why they died and if they figure that out, it might move forward on solving this problem faster,” said Jones.

Olsen said anglers who catch fish that show signs of disease should call him at (406) 533-8451.