The California Department of Fish and Wildlife’s (CDFW) Northern Region Inland Fisheries Program and Heritage and Wild Trout Program staff will soon reintroduce a small population of rare rescued trout to their native waters in the McCloud River in Shasta County.
McCloud River Redband Trout (Oncorhynchus mykiss stonei) is one of several sensitive and unique fish species that has required human intervention in order to ensure their survival during California’s continuing drought.
“The drought continues to be devastating on the populations of these important fish,” said Andrew Jensen, a biologist with CDFW’s Northern Region Inland Fisheries Program. “If we did not take action to save them during the summers, small, independent populations may have succumbed. Our proactive rescue efforts will help maintain this unique species for the future.”
CDFW biologists monitoring McCloud Redband streams (tributaries of the upper McCloud River) from late 2013 through mid-2015 found that drought effects were causing perilous conditions for the fish in both winter (with sections of the streams freezing over) and summer (with sections of the streams going dry). McCloud Redband, a state-listed Species of Special Concern, are in no immediate risk of extinction but their populations are small, fragmented and exist only in a few small streams. Rescue operations by CDFW in 2013-15 greatly reduced the drought mortality of the species.
Anticipating potential drought impacts on sensitive wild fish populations, CDFW installed self-contained Recirculating Aquaculture Systems (RAS) at several CDFW hatcheries throughout the state last year. The RAS enable the hatcheries to safely house rescued wild fish until environmental conditions improve. One of these facilities, CDFW’s Mt. Shasta Hatchery, was selected to serve as a drought safe haven for the McCloud Redband due to its proximity to the imperiled streams. More than 1,000 McCloud Redband were brought to the facility, where many were spawned by CDFW staff.
Today much of California remains in a drought, but the upper McCloud River watershed received some relief in the first half of 2016, with near-normal precipitation during the winter and spring. CDFW fisheries biologists believe that these improved habitat conditions (and forecast conditions) will support the release of the rescued McCloud Redband Trout.
Both the rescued adult fish and the hatchery-origin juveniles will be released beginning this week in sections of the stream that will provide the best chance of long-term success with minimal impacts to the existing natural-origin population. All the released fish will be tagged, allowing fisheries biologists to track their movement and survival after release into the river.