Passage and behavior of radio-tagged adult Pacific lampreys (Entosphenus tridentatus) at the Willamette Falls Project, Oregon.
Northwest Science
By: Matthew G. Mesa, Robert J. Magie, and Elizabeth S. Copeland
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Abstract
Populations of Pacific lamprey (Entosphenus tridentatus) in the Columbia River basin have declined and passage problems at dams are a contributing factor. We used radio telemetry to monitor the passage of adult Pacific lampreys at the Willamette Falls Project (a hydroelectric dam integrated into a natural falls) on the Willamette River near Portland, Oregon. In 2005 and 2006, fish were captured at the Project, implanted with a radio tag, and released downstream. We tagged 136 lampreys in 2005 and 107 in 2006. Over 90% of the fish returned to the Project in 7 – 9 h and most were detected from 2000 – 2300 h. In 2005, 43 fish (34%) passed the dam via the fishway, with peak passage in August. No fish passed over the falls, but 13% ascended at least partway up the falls. In 2006, 24 fish (23%) passed the Project using the fishway, with most prior to 9 June when the powerhouse was off. Although 19 lampreys ascended the falls, only two passed via this route. The time for fish to pass through the fishway ranged from 4 – 74 h, depending on route. Many fish stayed in the tailrace for hours to almost a year and eventually moved downstream. Our results indicate that passage of lampreys at the Project is lower than that for lampreys at dams on the Columbia River. Low passage success may result from low river flows, impediments in fishways, delayed tagging effects, changing environmental conditions, or performance or behavioral constraints.
Suggested Citation
Mesa, M.G., Magie, R.J., Copeland, E.S., 2010, Passage and behavior of radio-tagged adult Pacific lampreys (Entosphenus tridentatus) at the Willamette Falls Project, Oregon.: Northwest Science, v. 84, no. 3, p. 233-242, https://doi.org/10.3955/046.084.0303.
ISSN: 2161-9859 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Passage and behavior of radio-tagged adult Pacific lampreys (Entosphenus tridentatus) at the Willamette Falls Project, Oregon. |
| Series title | Northwest Science |
| DOI | 10.3955/046.084.0303 |
| Volume | 84 |
| Issue | 3 |
| Year Published | 2010 |
| Language | English |
| Publisher | Northwest Scientific Association |
| Contributing office(s) | Western Fisheries Research Center |
| Description | 10 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Northwest Science |
| First page | 233 |
| Last page | 242 |
| Country | United States |
| State | Oregon |
| Additional Online Files (Y/N) | N |