Contents Introduction Habitat Range Population declines Current Greenback Status Catch and release fishing How you can help! Related links

Evolution of the Greenback Greenbacks are the most easterly of all cutthroats, evolving over two million years from Pacific salmon, steelhead and Coastal cutthroats, that migrated up the Columbia/Snake River system to Yellowstone and the Green/Colorado River system. Sometime during the most recent Ice Age (10-20,000 years ago) these ancestor fish somehow managed to cross over the Continental Divide to eastern Colorado--probably by way of mudslides or ice dams--and evolved in isolation thereafter to become a distinct subspecies.

Fish Migration Over Mountain Passes