FLAGSTAFF, Ariz. – The Colorado River through the Grand Canyon and its tributaries used to be home to eight native fish species.

That was before Glen Canyon Dam was built near the Arizona-Utah border, making the environment less-than-ideal for spawning.

Officials with the National Park Service say they want to make sure native fish still present have the best chance for survival.

A 20-year fisheries management plan released this week puts in place measures to protect those fish and ensure that anglers have plenty of non-native rainbow trout to catch below the dam.

Biologists and volunteers would boost populations of endangered humpback chub by placing them in select Grand Canyon creeks. They’ll also study habitat for the endangered razorback sucker on the far western edge of the national park near Lake Mead.