Pumping Oxygen In A Lake To Try To Save Fish Facing Climate Change

You'd never suspect it on a whisper-still morning, with the mountains and marsh reflecting off the water, but Upper Klamath Lake in southern Oregon is a tough place to be a fish.
The shortnose and Lost River suckers provide a case in point. The two species of fish, which look like a big-lipped cross between a carp and cod, used to be common in this lake. For millennia, they were an important traditional food source for the local tribes. The federal government considers them endangered species.
There's a population of long-lived adult suckers hanging on and continuing to reproduce, but virtually none of their offspring are surviving for longer than a year.
"The juvenile sucker, they're dying off. They're not recruiting new adults," says Mason Terry, a renewable energy professor at the Oregon Institute of Technology in Klamath Falls.
Poor water quality — exacerbated by the warming climate — is considered a significant cause of the sucker death. One key problem for the Upper Klamath is a low dissolved oxygen issue called hypoxia.

Fish breathe oxygen out of the water, and the oxygen levels here can drop extremely low, especially in late summer. That coincides with the time juvenile suckers appear to just vanish from the lake.