Drought Prompts Fish Evacuation at American River and Nimbus Hatcheries
With a fourth year of extreme drought conditions reducing the cold water supply available, the California Department of Fish and Wildlife (CDFW) is moving fish out of the American River and the Nimbus hatcheries for the second year in a row.
Bureau of Reclamation models suggest water temperatures at the hatcheries could be at lethal levels for cold water fish by August. CDFW has already begun to stock American River Hatchery rainbow and brown trout into state waters earlier than normal. These fish range from small fingerlings to the larger catchable size. The accelerated planting schedule will continue through mid-July when all the fish in the raceways are expected to be evacuated. This includes all the fingerling size rainbow trout that would normally be held in the hatchery to grow to catchable size for next year.
A new, state-of-the-art building at American River Hatchery, completed in early June using emergency drought funds, will enable CDFW to raise Lahontan cutthroat trout through the summer for planting into eastern sierra lakes and streams. The new building will also enable CDFW to hold a small group of rainbow trout fingerlings that are scheduled to be stocked in west side sierra put-and-grow fisheries by airplane in July. The new hatchery building utilizes water filters, ultraviolet sterilization techniques and large water chillers to keep water quality and temperatures at ideal levels for trout rearing. However, the new technology is limited to the hatchery building and not the raceways, which will limit capacity to include only the Lahontan cutthroat trout once the fish start to grow to larger sizes.
Nimbus Hatchery has already begun relocating some 330,000 steelhead to the Feather River Hatchery Annex to be held through the summer. When the water temperature at the Nimbus Hatchery returns to suitable levels in the fall, the steelhead will be brought back to Nimbus to finish growing and imprinting then will be released into the lower American River. The Feather River Hatchery Annex is supplied by a series of groundwater wells that maintain cool water temperatures throughout the year.
The fall run Chinook salmon from Nimbus Hatchery have all been released into state waterways. If necessary, the chilled American River Hatchery building will be used this fall to incubate and hatch Chinook salmon from Nimbus Hatchery.
"Unfortunately, the situation is similar to last year," said Jay Rowan, Acting Senior Hatchery Supervisor for CDFW's North Central Region. "We have begun to implement contingency plans to avoid major fish losses in the two hatcheries. We want to do the best job we can to provide California anglers with good fishing experiences and communicate when there will be deviations from normal practices. With that in mind, we want to let anglers in the area know that a lot more fish than normal will be going out into area waters served by American River Hatchery."
Rowan said that the number of fish planted at various waterbodies will increase as the planting timeframe decreases, so the fishing should be very good through the summer at foothill and mountain elevation put-and-take waters. Early fish plants now mean there won't be as many fish available to plant in the lower elevation fall and winter fisheries, so the fishing may drop off later in the season if the fish don't hold over well.
American River Hatchery operations focus on rearing rainbow and Lahontan cutthroat trout and kokanee salmon for recreational angling, predominantly in waters within the North Central Region. Nimbus Hatchery takes salmon and steelhead eggs from the American River and rears them to fish for six months to a year, until they are ready to be put back in the system.
To the south, San Joaquin Hatchery near Fresno expects to experience high water temperatures this summer. Transferring and stocking fish in advance of high water temperatures is planned. CDFW hopes to maintain some trout at low densities at the hatchery for the winter stocking season.
Annually, CDFW works with the Bureau of Reclamation to ensure its operations provide suitable conditions for fish at hatcheries and in the river. This year, conditions are forecasted to be dire with little flexibility in operations. Similar to last year, low reservoir storage and minimal snow pack will result high water temperatures over summer and very low river flows by fall.
Fall and winter rains, if received in sufficient amounts, will cool water temperatures enough to allow both hatcheries to come back online and resume operations.