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Become an expert on bull trout. Learn about where they live, their life cycle and their characteristics.

Take No Bull

Bull Trout are in need of protection due to loss of habitat and habitat damage as well as pressure from introduced species. Poaching and unintentional angling mortality  (often due to misidentification) are also of grave concern. Conservation and careful attention by anglers is vital to keeping the bull trout present in its ancestral aquatic habitat.

These identification tips are designed to make unintentional poaching a thing of the past and allow wildlife biologists to help bull trout increase in number.


  • TAIL: Slightly Forked
  • DORSAL FIN: Without spots or other marks. NO BLACK - PUT IT BACK
  • BODY: Silvery to light olive with yellow, orange, or pink spots; darker olive-colored on back with yellow or cream-colored spots
  • APPEARANCE: Usually drab coloration, but adult (usually over 14 inches) may have bright orange colors on belly and flanks, black on head, and white-edged fins during fall. White leading edges on pectoral, pelvic, and anal fins is evident year 'round.

Geographical location

Because bull trout live in a specific area, first consider where you are. Western Montana, Idaho, Washington, Oregon, Nevada, Southern British Columbia and Southwest Alberta are all prime bull trout habitat. They are found in the Flathead, Clark Fork, Kootenai and other river drainages.

Life cycle

  • Bull trout spawn in September and early October. They migrate up to 150 miles from lakes such as Pend Oreille Lake in Idaho, and spawn in small tributary streams (adfluvial lifestyle).
  • Some bull trout live as adults in rivers like the Blackfoot River in western Montana (fluvial lifestyle). Others can live their entire lives in smaller streams, such as those in the Clarkfork River tributaries (resident lifestyle).
  • After spawning, most bull trout return downstream to their natal lake or stream. Some adfluvial bull trout have been known to spawn every other year, due to the stress of their arduous spawning migrations. Most bull trout spawners are 5-9 years of age.
  • Females bury their eggs in nests or “redds”, about six inches deep in the streambed gravel. These redds can be as large as the bed of a full size pick-up truck.


  • Named for their impressive size, bull trout are Montana’s largest trout and can be 36 inches long. The largest bull trout, caught in Lake Pend Oreille in Idaho, weighed more than 32 pounds.