A review and assessment of transportation studies for juvenile Chinook salmon in the Snake River

We reviewed research conducted by the U.S. National Marine Fisheries Service from 1968 through 1989 on the benefits of using trucks and barges to transport migrating juvenile Chinook salmon Onchorhynchus tsawytscha from the Snake River around dams and reservoirs in the lower Snake and Columbia rivers. Early results from studies that used trucks indicated that Chinook salmon benefited from transportation: therefore, transportation was adopted as a management strategy by the late 1970s. Our review shows that large-scale transportation by truck was unlikely to benefit survival of juvenile Chinook salmon. Our results from reviewing more recent studies indicate that the use of barges to transport juvenile Chinook salmon may result in improved survival. Benefits may be lower than previously reported because results may have been biased by experimental design: however, even after we adjusted for those potential violations, results from four of six studies on the use of barges indicated that survival of transported fish was higher than survival of fish left to migrate in-river. Because the improved survival from barging may not be enough to ensure recovery of endangered stocks of Chinook salmon, we recommend that management of Snake River Chinook salmon not rely heavily on any one management technique