Golden Gate Salmon Association (GGS) Project D.3 Improve Trucking Techniques for Hatchery Salmon Background and Scientific Analysis December 4, 20131
The goal of this project is to improve trucking results especially at the Federal Coleman Hatchery on Battle Creek where there are poor hatchery returns and high straying rates from trucking… The survival of trucked and acclimated fish was substantially higher than that of fish released at the hatchery basin. The combined average trucking improvement from all the hatcheries was 3.49 to 1. The improvements ranged from a high of 71 to 1 at the Feather River hatchery to a low of 1.8 to 1 at Coleman. These figures mean trucking produces many thousands of additional adults for harvest or for return. But, the returns are still very low when compared to the losses that are avoided by trucking the fish around the rivers and the Delta. Studies of the mortality of juveniles migrating down the Sacramento River and through the Delta range up to 90%. Avoiding this loss indicates that the survival of trucked fish should be more in the order of 10 to 1 over basin released fish. Current science cannot explain this difference. More research is needed.
Clearly, their Exhibit 1 below depicts the benefits of trucking in avoiding the many risks in the up to 200 mile trip to the Ocean for Central Valley salmon. Trucking bypasses much of risk, but results in high straying rates. As described previously, barging and out-planting offer potential reduction in straying without giving up the huge advantage in survival and production.
Smolt Production from hatchery adults. Kathryn E. Kostow , Anne R. Marshall and Stevan R. Phelps. 2011.2 Naturally Spawning Hatchery Steelhead Contribute to Smolt Production but Experience Low Reproductive Success
Our data support a conclusion that hatchery summer steelhead adults and their offspring contribute to wild winter steelhead population declines through competition for spawning and rearing habitats.
There is considerable scientific study that indicates that the offspring of hatchery salmon and steelhead have lower reproductive success than wild native fish. Wild native fish have many general and locally adapted traits that are often missing in hatchery fish. For Central Valley salmon and steelhead, many of these native traits were lost long ago. Tribes in northern California hope to bring some traits back from wild salmon sent from California to New Zealand a hundred years ago. Recently, special traits involving greater growth and longevity of Lahontan Cutthroat Trout were restored to Pyramid Lake in Nevada from an outside source.
In the end, we can only hope that restored “wild” populations will begin the natural selection process in restoring traits that contribute to higher survival and production. At minimum, hatcheries should discontinue practices that degrade natural diversity and genetic inheritance, and should focus on improving diversity and traits that enhance the ability to survive Valley conditions now and in the future.