A Simon Fraser University study has found that steelhead trout have a remarkable life-cycle variation that responds to changes in temperature and numbers of other species of salmon. They may go to the ocean when they are only a year old and the size of a pinky finger, or when they are five years old and the size of a standard ruler. The study appears this week in the journal Ecosphere.
Researchers found that the steelhead trout age of migration, as well as their size and numbers, is controlled by a combination of temperature, co-occurring salmon, and other factors.
In years following large returns of pink salmon, steelhead migrated to sea at a younger age, and in some time periods, there were more young steelhead that were produced from the river system. “We think that energy-rich eggs from spawning pink salmon provide an important food source for young steelhead,” says SFU biology PhD student Colin Bailey, who is leading the project.