The female then digs another pit and the process is repeated. The process continues for two or three days until all of the female's eggs are safely covered by gravel. Trout usually remain in the tributaries for two to four weeks after spawning. Eventually, they will make their way back to the main rivers. At Yellowstone Lake, older and larger fish begin the spawning migration first.
Males migrate earlier than females and remain longer in the spawning streams.
In Yellowstone National Park, there are regulations that protect fish during spawning runs. Due to the absence of fishing pressure, about 26 percent of the spawning fish in Yellowstone Lake populations survive to spawn again. Females from the Yellowstone Lake population usually spawn for the first time at an average length of 14 inches, and may deposit 1,300 eggs. The majority are consumed by predators such as adult fish, birds, and mammals. Some of the problems that have caused a decline in native cutthroat trout populations include habitat loss, human diversion of water from spawning tributaries, and introduction of non-native competing species of trout.