Why Brown Trout Run

“Brown trout spawning runs are sparked by a combination of water temperature and the number of daylight hours, called a photo period, according to Bruce Rich, fisheries manager for the Montana Department of Fish, Wildlife and Park’s Region 3. A sudden decrease in temperature of some duration will trigger a spawning run, he said.” Brett French describes the notable Hebgen Lake/Madison River brown trout and rainbow trout runs in the Billings Gazette.