Illustrations Courtesy of Joseph Tomelleri

Brown Trout - Salmo trutta

The brown trout belongs to an entirely different genus (Salmo) than our native trout species. They evolved in Europe and western Asia and were introduced to North America in 1883 and to Montana in 1889 in the Madison River. Today, brown trout are found throughout most of Montana except the northwest and parts of the east. Generally, they prefer lower gradient, larger streams than cutthroat and rainbow, and they also do well in many reservoirs.

Brown trout were widely stocked in the first half of the 20th century, but today most come from natural reproduction. Brown trout are great competitors and generally are more tolerant of dewatering, warmer water and other environmental disturbances than our other trout species. They are much more immune to the effects of whirling disease than rainbows and cutthroats. Brown trout spawn in gravel redds like our native trout but their spawning season is in the fall, after irrigation season. This also gives them a distinct advantage in some habitats.

Rainbow Trout - Oncorhynchus mykiss

The rainbow trout is Montana's number one game fish. Rainbow trout were introduced from numerous hatchery stocks into virtually every suitable habitat in the state, beginning in 1889.

Rainbow trout introductions have caused a severe reduction in the range of the native cutthroat trout through hybridization and competition. Rainbow trout fare well under a wide range of habitat conditions from ponds to reservoirs, lakes, and streams. Rainbow are efficient at feeding on plankton, aquatic and terrestrial insects, and occasionally some smaller fishes. They spawn in early spring in running water, usually April or May, and maintain themselves quite nicely if the habitat is not degraded.

Scientists believe that only the inland Columbia redband form of rainbow trout in the upper Kootenai River drainage are native to this state. This small population of native trout are a Fish of Special Concern.

Brook Trout - Salvelinus fontinalis

The "brookie" or brook trout was introduced to Montana from eastern North America in 1889. They can be recognized by the distinctive light worm-like markings on their backs. Brookies, too, were extensively propagated and stocked in the early half of the 20th century, although seldom so today. Brook trout reproduce vigorously, and can quickly overpopulate limited habitat (as any angler who has caught stunted 5" brookies in stocked high mountain lakes will testify).

Brook trout, while enjoyed by many for their flesh and easiness to catch, are disastrous for Montana's native trout. Brook trout interbreed with Bull trout, damaging those few pure populations that remain. Brook trout also voraciously out-compete native cutthroat and redbands for habitat. Because of these threats, brook trout are being removed from many streams with poisons, and prevented from invading upstream refuges for native trout with barriers. Unfortunately, brook trout are generally very difficult and expensive to eradicate from streams. Ironically, the MFWP manages some waters (like Georgetown Lake) as trophy water for brook trout, requiring all brook trout caught to be safely released. If you catch and kill a brook trout in a Montana stream, you do native trout a favor. But, be sure there is black in the fins - otherwise you've illegally killed a Bull trout!

Brook trout are, for better or worse, common throughout most of the western two-thirds of the state in all major drainages. Brook trout favor small, cold, headwaters streams and ponds (especially beaver ponds). Brookies spawn over gravel in streams or in upwelling, percolating spring areas in lakes and ponds. Brook trout will eat nearly any living organism, and larger fish can be voracious predators on other fish and even their own young. For this reason, there are sometimes a couple of very large kin-eating brookies in overpopulated high mountain lakes.

As mentioned, brook trout will readily breed with other types of char, including native Bull trout and the introduced Brown trout. The offspring of a brook/brown interbreeding, called tiger trout, have the markings of a tiger or giraffe. They are very rare since mortality of eggs and newly hatched fish is high and hybrids reaching adulthood are usually sterile.

Lake Trout - Salvelinus namaycush

The lake trout is a char of the same genus as bull trout and brook trout. Lake trout are native to a few waters in the St. Mary and Missouri River drainages. The agency-sponsored stocking of non-native lake trout to Flathead Lake and Fort Peck Reservoir has been disastrous, since lake trout devour native trout and breed like crazy. Semi-annual fishing events are held on Flathead Lake to reduce the lake trout population, with questionable success. Lake trout have made their way into Swan Lake (which feeds Flathead Lake), where they pose a huge threat to native bull trout and westslope cutthroat populations.

Lake trout inhabit very deep, cold lakes, living in water up to 200 feet deep. They spawn in the fall on the rocky substrate of the shoreline. They scatter or broadcast their spawn, a rarity in the trout group. Small lake trout feed on plankton and aquatic invertebrates but fish over 2 to 3 pounds eat a fish diet.

Golden Trout - Oncorhynchus mykiss aguabonita

The golden trout is a California species that was introduced in Montana in 1907. There are currently about 20 golden trout populations in the high mountain lakes of western and south central Montana. They provide a unique opportunity to catch a beautiful fish in a pristine environment. Golden trout up to 4 pounds have been caught in Montana but typical size is usually 6-12 inches. Golden trout are spring spawners and can usually be found in inlet or outlet streams to high mountain lakes around the Fourth of July.

Found only in mountain lakes in Montana; also successful in clear, cool lakes at lower elevations. Spawns in redds over clean gravel of fist size and smaller. Spawns mostly in outlets, but also in inlets and occasionally along lake shoals. Readily hybrizes with cutthroat and rainbow. Demise of former 50+ populations of golden trout largely due to introduction of other spring spawning species, whether by hybridization or replacement.