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Notes:
Here’s a summary chart of returns to Bonneville Dam from no-term and short-term releases. Columns contain collection year, Fish in, which is the number of fish collected at Prosser for that treatment, Returned to Bonneville, which is the percent of the fish-in number that were detected in the fish ladder at Bonneville Dam; and, S release to Ocean is the survival estimate from the release site below Bonneville Dam to the Ocean acoustic array. In 2002 and 2003, we collected fish only for short-term treatments. These fish were PIT tagged and released below Bonneville Dam, no acoustic tags were used. Returns to Bonneville Dam were 9 and 4% of the number of fish collected for that treatment. Most returning fish (about 70%) arrived at Bonneville Dam during the first fall. The remaining 30% arrived in the second fall. This fish are generally termed skip spawners. In 2004, no-term returns were 7% and short-term returns were 5%. This was the more average year in terms of flow and water temperature. In 2005, during the lower flow / higher water temperature year, returns to Bonneville were only 1% for the no-term and 0 for the short-term group. In 2006, we had high survivals to the ocean (70.1% for no-term and 65.1% for short-term) but we didn’t have any detections at Bonneville Dam in the fall of 2006. Typically, we would see about 70% of the return the first fall. But we’re hopeful that we’ll see a large proportion of skip spawners from the 2006 release.