Brian Marotz recalls running into a rickety, defunct fish hatchery just off Montana’s North Fork Flathead River in the mid-1990s. As a state fisheries biologist who was guiding mitigation work for native fish species, Marotz was surprised to see there were still rainbow trout in the hatchery, and shocked to learn the fish had potential to escape into the North Fork, presenting hybridization threats to native fish in the Flathead River system.