Fish species of the Big Hole River

Arctic grayling

native, species of concern

Thymallus arcticus

Arctic grayling are easily caught by anglers and are susceptible to overharvest. The Big Hole River supports the last population of fluvial (i.e., stream-dwelling) arctic grayling in the lower 48 states. Grayling were declining by the 1980s in the Big Hole, but the species is now recovering thanks to a collaborative effort among private landowners, federal and state personnel, and watershed groups, along with a catch-and-release angling regulation preventing harvest.

westslope cutthroat trout

native, species of concern

Oncorhynchus clarkii lewisi

The cutthroat trout is Montana’s State Fish. Westslope cutthroat trout were first described by the Lewis and Clark Expedition in 1805 near Great Falls and are native to Montana in the Upper Missouri and Saskatchewan river drainages east of the Continental Divide and in the Upper Columbia Basin west of the Divide. Westslope cutthroat trout are the only native trout to the Big Hole drainage.  

mountain whitefish


Prosopium williamsoni

The mountain whitefish is familiar to most Montanans. This widespread native fish is primarily a stream-dwelling species, but populations are also found in reservoirs and lakes. The mountain whitefish is found in abundance in most clear, cold rivers in the western drainages and eastern mountain front of Montana. The typical mountain whitefish is a cylindrical 10-16 inch fish, but they can reach a weight of 5 pounds.  

burbot or ling


Lota lota

The burbot is easily recognized by its single chin barbel. The only freshwater cod species, burbot is native to most of Canada and the northern United States and is found in all three major river drainages in Montana. Burbot are usually found in larger streams and cold, deep lakes and reservoirs. They are peculiar in that they spawn during winter, under the ice. They are also largely nocturnal and have an enthusiastic following among fishermen. Burbot are voracious predators and opportunistic feeders.

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 aquatic 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. 

brook trout

Salvelinus fontinalis

The "brookie" or brook trout was introduced in Montana from eastern United States in 1889. It was extensively propagated and stocked in the early half of the 20th century. Brook trout favor small, cold, headwaters streams and ponds, particularly those that are spring-fed. Brook trout are common throughout most of the western two-thirds of the state in all major drainages.  

brown trout

Salmo trutta

The brown trout belongs to a different genus than our native trout species. Brown trout evolved in Europe and western Asia. They were introduced to North America in 1883 and to Montana in 1889 and were stocked in the Madison River. Brown trout were widely stocked in the first half of this century, but today are sustained by natural reproduction. Today, brown trout are found throughout most of Montana except the northwest and eastern parts of the State. Generally, they prefer lower gradient and larger streams than cutthroat and rainbow trout, and they also do well in reservoirs.

We protect, conserve, and enhance the free-flowing Big Hole River and its unique culture, fisheries, and wildlife.

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The Big Hole River Foundation is a 501(C)(3) public charity.
Big Hole River Foundation
PO Box 176
Divide, Montana 59727