June 17 (Reuters) - Millions of young rainbow and steelhead trout are being evacuated from California's most productive hatchery complex as summer heat and the state's ongoing drought combine to make the water too warm for them to survive, officials said Tuesday.
Workers clad in overalls used nets to scoop up thousands of foot-long steelhead and load them onto trucks on Tuesday, part of a weeks-long effort to move the fish to cooler lakes and streams where they will have a better chance of surviving, said Andrew Hughan, a spokesman for the California Department of Fish and Wildlife.
"The water is expected to reach lethal temperatures for these fish," said William Cox, hatchery program manager for the state. "We've engaged in an evacuation plan so these fish don't just sit here in the hatchery and die."
California is in the third year of a catastrophic drought that has depleted the Sierra Nevada snowpack that normally feeds the state's rivers and streams with cool water.
Democratic Governor Jerry Brown declared the state's drought to be an emergency last January, committing millions to help stricken communities and temporarily easing protections for endangered fish to allow pumping from the fragile San Joaquin-Sacramento River delta.
By the end of this week, all fish will be gone from the Nimbus and American River Hatcheries, marking the first time that the hatcheries have been completely evacuated, Cox said.
The water flowing through the side-by-side hatcheries on the American River near Sacramento normally hovers around 65 degrees, even in summer, Cox said. But this year, the water flowing into the hatcheries' tanks could top 78 degrees.
"The fish in the warm waters are constantly stressed," Cox said. "Their immune systems don't work well, and a lot of the bacterial pathogens have an advantage."
The fish, loaded onto tractor-trailers with steel or fiberglass tanks equipped with oxygen pumps, are being released up to six months earlier than usual, Cox said.
Altogether, about 2 million rainbow trout and 435,000 steelhead will be moved, he said.
The fish will be smaller than they normally are when "planted" in lakes and streams, but even so they will be more likely to survive than they would if left in the hatcheries' warming tanks, Cox said.
Officials are expecting the water to cool enough to begin breeding fish again next year in November. (Reporting by Sharon Bernstein; Editing by Jim Loney)