Alternative barging strategies to improve survival of transported juvenile salmonids, 2008

In spring 2008, we continued a multi-year study to test the hypothesis that release of transported fish in the lower Columbia River estuary near Astoria (river kilometer 10) would produce higher adult returns than release at Skamania Landing, the established location just below Bonneville Dam (rkm 225). To evaluate this hypothesis, we released transported groups of juvenile Pacific salmon Oncorhynchus spp. to both sites for comparison of smolt-to-adult return rates (SARs) from each group. We speculated that moving the release site 215 km downstream could decrease smolt mortality due to predation by piscivorous fish and birds. Releases in 2008 made up the third and final consecutive year of juvenile releases for this study. Adults returning over the next several years will provide data to test this hypothesis. Contract no. W68SBV60307671 Contract no. W68SBV60418618