California Rice Pilot Salmon Project Yields Great Results
By Paul Buttner
The second year of our Pilot Salmon Project fieldwork has yielded some exciting results and should pave the way for the Rice Commission and our fish conservation partners to develop methods to utilize winter-flooded rice fields to help struggling salmon populations.
In late-March, we released nearly 350 baby salmon that were raised in rice fields. Later, we released a set of control groups that were reared and released using more traditional approaches. Fish in both of these groups were fitted with a very sophisticated tag, allowing us to track their travels through the watershed and out to the ocean. Our hope was to demonstrate rice field-reared fish might survive their journey out to the ocean better than those that are raised in hatcheries. We hypothesized this possible outcome based on previous studies showing that salmon grow very fast in rice fields because of the abundance of their natural food sources in these fields. I’m happy to say that our 2020 graduating class of our young salmon did not let us down!
Before getting to the results, it’s probably best to understand what reasonably expected salmon survival rates are from year-to-year. In extremely high-water years, it is possible to get to as high as 15 to 20 percent survival. However, those years are quite rare. In drought years, similar to the 2019/20 season, expected survival is typically around zero to 3 percent and is often close to zero.
The outmigration survival rate of our 2020 rice field-reared salmon was nearly 4.5 percent. This was nearly 4.5 times higher than our control groups and substantially higher than other similar tagging study during this period. We could not be happier with these results and they will now serve as the basis for further work by CRC and its fish conservation partners to continue efforts to develop a larger-scale strategy to use our fields to help salmon just as we have used them to help birds for decades now.
We want to thank UC Davis and CalTrout for their extraordinary work in the field over these past two years. And, of course, this project could not be possible without the help of our funding partners and participating growers. Special thanks to the Natural Resources Conservation Service and Syngenta for their major contributions and our long list of supporting partners including S.D. Bechtel Jr. Foundation, GrowWest, Corteva, Valent, Almond Board of California, NovaSource, Conaway Ranch and River Garden Farms. We also want to specially recognize both U.S. Fish and Wildlife Service and California Department of Fish and Wildlife for supplying us with hatchery fish to support this important work and for technical expertise on key aspects of the work.