Adult Pacific Lamprey Migration in the Lower Columbia River: 2011 Half-Duplex Pit Tag Studies
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION SEATTLE WA NORTHWEST FISHERIES SCIENCE CENTER
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We tagged adult Pacific lamprey Entosphenus tridentatus collected at Bonneville Dam with half duplex HD passive integrated transponder PIT tags and monitored their passage and migration behaviors at Bonneville, The Dalles, John Day, McNary, Ice Harbor, Lower Monumental, Lower Granite, and Priest Rapids dams. Our objectives were to calculate lamprey passage times, to estimate escapement past the monitored sites, and to evaluate potential physiological and environmental correlates with lamprey migration through the study area. In total, we HD-PIT tagged 929 lampreys in 2011 800 were released downstream from Bonneville Dam near Hamilton Island, 109 were released upstream from Bonneville Dam near Stevenson, WA, and 20 were released directly into the Cascades Island lamprey passage structure LPS. An additional 85 lampreys were double-tagged with HD-PIT tags and acoustic transmitters JSATS, and results from these fish are presented in a separate report. The 2011 escapement estimate from release below Bonneville Dam past the dam was 56, higher than estimates in the 2005-2009 HD-PIT studies 41-53. Escapement from the top of Bonneville Dam to the top The Dalles Dam 52 and from the top of The Dalles Dam to the top of John Day Dam 80 was also higher than or similar to previous estimates. Large lampreys in the downstream release group were significantly more likely than small lampreys to pass through most dam-to-dam reaches. As in previous years, lampreys last detected at upriver sites were significantly larger than those last recorded closer to the release site, indicating that size-dependent effects on migration distance and final distribution were likely.
- Acoustic Detection and Detectors