The Current Magazine Fall 2016 - Page 32

Fish in Peril

The true, pure strain McCloud River redband trout were hit especially hard by the California drought. The creeks that hold pure strain McCloud redband are disconnected from the mainstem McCloud River. These small creeks well up from springs and only flow for a mile or two before going sub-surface again. Due to the nature of the habitats and how they swell with the spring runoff then dry up and become disconnected in the summer, there is always some level of mortality on a few of these creeks. However, in 2013, DFW biologists noticed conditions were reaching critical levels for fish in a large portion of the available habitat. In late summer, dissolved oxygen levels were getting low and temperatures were rising. In the winter, the small creeks are subject to freezing if the water levels and flow are too low. After careful consideration, the hard decision was made to bring some of these fish into captivity to reduce mortality and potentially lose important meta populations in the wild.

DFW to the Rescue

Fortunately, the DFW has a hatchery facility nearby in the town of Mount Shasta that is run off very cold spring source water, much like the McCloud River redband are used to in their natal streams. A portion of the facility was equipped with a state of the art self-contained Recirculating Aquaculture Systems (RAS). Fish captured from the wild were kept separate in their distinct family groups from each individual stream and treated different than typical hatchery raised fish that are to be released for sport. To keep the McCloud River redband as “wild” as possible, handling was kept at a minimum to avoid association with humans and food and they were fed natural insects to while in the hatchery facility.

Some fish populations were in captivity for over two years. These fish were bred twice, once each year, and produced two generations of offspring while at the hatchery. Genetic testing was done on each fish and they were then cross-bred according to a genetic matrix on a paper drafted by UC Davis to increase genetic diversity while maintaining the purest genetic makeup of the different family groups and meta populations.

PROJECT UPDATE