Photo by Pat Clayton,

Brown Trout

Salmo trutti. By Tom Dickson

This story is featured in Montana Outdoors September-October 2010 issue

It’s hard enough being a hunter this time of year, what with archery, backcountry deer and elk, pronghorn, waterfowl, and upland bird seasons opening one after another. But now is also when big browns become especially aggressive and wildly attack streamers. Hard as it might be, especially for my sad-eyed springer spaniel, I sometimes forego hunting a few days each fall to cast Woolly Buggers at surly browns lurking along riverbanks.

Unlike native bull, cutthroat, and redband trout, browns first arrived in the West during the late 1800s as part of federal stocking programs. The fish were imported from Germany and Scotland’s Loch Leven. (Some old-timers still refer to them as German browns or Loch Leven browns.) Brown trout were stocked in waters of Yellowstone National Park, from which they migrated north along the Yellowstone River into Montana. State fisheries managers later began aggressive stocking efforts in other rivers and lakes. Montana stopped stocking most rivers in the early 1970s after learning that the trout were naturally self-sustaining.

Brown trout live in central and southwestern Montana in valley streams and rivers such as the Madison and Big Hole as well as in many reservoirs and lakes. They usually coexist with rainbow trout. Because browns can survive in warmer, murkier water, they are often more abundant than rainbows farther downstream, such as below Saint Xavier on the Bighorn.

Mating season
Unlike spring-spawning cutthroats and rainbows, browns—along with bull trout and brookies—spawn in fall. During spawning season, the male’s lower jaw develops a hook at the tip, called a kype, which fits into a groove that forms in the upper jaw. Biologists think males use their kype as a weapon to fight off rival males; it may also attract females, like a bull elk’s antlers or a sage-grouse’s fanned tail.

A brown trout has an olive back, and the fish’s golden sides, often described as buttery colored, are covered with black and red spots, often with pale halos.

Any angler knows that browns are harder to catch than other trout species. But are they smarter? According to trout biology guru Robert J. Behnke, the brown’s brain is no larger or otherwise different from those of other trout. He speculates that the answer lies in the brown trout’s aversion to light and adaptation to murkier water. “The ret­ina…is better adapted to optimally function in dim light,” he wrote in a 1986 column in Trout magazine. “Thus, browns are more oriented to dense cover and shaded areas such as deep undercut banks, and more prone to nocturnal feeding.”

That’s not to say browns can’t be caught at noon on sunny days out in the open. But in such conditions it’s more likely that a rainbow or cutthroat trout will take your fly than a brown.

Once browns reach 14 inches or so, they begin eating fish as well as aquatic insects. This protein boost allows them to reach large sizes in many rivers. For instance, the trout silhouettes lining the wall of Dan Bailey’s Fly Shop in Liv­ingston attest to the massive browns caught on the Yellowstone. It’s rare for trout to live long enough to top 10 pounds. They usually die of old age after four or five years, though a few can survive ten years or more. Brown trout grow larger in lakes than in rivers. Montana’s state record is a 29-pounder caught in Wade Lake in 1966.

Though they have displaced native cutthroat trout and arctic grayling in some waters, brown trout are extremely popular with anglers. The best way to conserve brown trout is by ensuring the fish have adequate stream flows, cool water, silt-free spawning gravel, and abundant habitat such as pools, riffles, and overhead cover.Bear bullet

Tom Dickson is editor of Montana Outdoors.