Brown trout (salmo trutta) are non-native species to Montana. They are native to Scotland and Germany. The first brown trout in the state were introduced to the Madison River in 1889. 

A typical female brown trout produces about 2,000 eggs per kilogram (900 eggs per pound) of body weight at spawning.  

In nature, only 1-2 per cent of these eggs will survive to spawning adulthood. 

Brown trout eggs need a constant supply of cold, clean and well oxygenated water. 

The brown trout has been stocked in 45 states in the U.S. There is a self sustaining population in 34 of the 50 states. 

Experimental studies of stocked and wild brown trout in natural conditions demonstrate that farm reared fish have poor survival and reproduction compared to wild fish (often less than 10%). 

Large brown trout will also feed on small terrestrial animals that fall into the water, such as baby birds falling from overhanging nests, or even swimming mice or voles. 

The IGFA all-tackle record brown trout record is 44lb. 5oz. Caught in New Zealand, Oct. 2020. 

October 27, 2020, New Zealand produced its second consecutive IGFA world record brown trout when a 44-pound, 5-ounce bruiser was caught in one of the country’s hydro canals. Here, Sean Colenso of the Razza Bar and Bistro—where a taxidermy mount of the fish will soon hang—shows off the 38.5-inch long trout caught by Seumas Petrie. (Photo courtesy of Sean Colenso)

The largest brown trout caught on a fly is 36lb. 6oz. taken in Austria, July, 2007. 

The Montana record brown trout is 32.43 lb. , caught in March, 2021, Marias River. 

Robbie Dockter of Conrad, Montana, holds the Montana state-record brown trout caught March 3 on the Marias River. The fish weighed 32.42 pounds. (Courtesy of Sierra Dockter)

Brown trout spawn in gravel redds like our native trout but their spawning season is in the fall. This gives them a distinct advantage in some habitats since their spawning and incubation period lies outside the irrigation season. Brown trout are more predaceous than rainbow or cutthroat. Large fish often feed at night on other fish as well as crayfish and other invertebrates. (Mt FWP). 

Rainbow and brown trout do not interbreed in the wild although ‘brownbows’ have been produced on fish farms. 

Brown trout numbers are dropping across southwest Montana — and biologists don’t know why. Angling pressure, warming water, and the ongoing drought could all be reasons behind that widespread decrease across many of the region’s rivers, but right now, Montana Fish, Wildlife & Parks (MFWP) biologists still are searching for exact answers and ways to stop the massive decline. Kristen A. Schmitt, Free Range American)