SACRAMENTO, Calif. -

Scientists say California's drought threatens some fish, birds and trees already struggling to survive.

Peter Moyle of the University of California, Davis, Center for Watershed Sciences says the state's fish are especially at risk.

California lists 37 types of fish as endangered, the Sacramento Bee reported Saturday.

Moyle said 80 percent of them could be extinct by the year 2100 given current trends.

Native fish can weather nature's occasional dry periods, but Moyle says the state-engineered water system has created the equivalent to perpetual drought conditions.

California is in its third dry year, and in January Gov. Jerry Brown declared a drought emergency.

In the drought, birds have fewer insects to feed on, and scientists say drier, warmer temperatures correlate with tree mortality in the foothills and Sierra Nevada.