This pristine lake has endured for 2m years. Why are its fish in crisis?

The tributary streams used by Hovsgol grayling for spawning are also drying up. “They no longer have water in them during the spring spawning season,” says Olaf Jensen, an associate professor at the University of Wisconsin-Madison. Nearly 80% of the 96 streams that once flowed into Lake Hovsgol are dry during the key months when the fish migrate.