Spawning patterns of Pacific Lamprey in tributaries to the Willamette River, Oregon

Transactions of the American Fisheries Society
By: , and 

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Abstract

Addressing the ongoing decline of Pacific Lamprey Entosphenus tridentatus across its range along the west coast of North America requires an understanding of all life history phases. Currently, spawning surveys (redd counts) are a common tool used to monitor returning adult salmonids, but the methods are in their infancy for Pacific Lamprey. To better understand the spawning phase, our objective was to assess temporal spawning trends, redd abundance, habitat use, and spatial patterns of spawning at multiple spatial scales for Pacific Lamprey in the Willamette River basin, Oregon. Although redd density varied considerably across surveyed reaches, the observed temporal patterns of spawning were related to physical habitat and hydrologic conditions. As has been documented in studies in other basins in the Pacific Northwest, we found that redds were often constructed in pool tailouts dominated by gravel, similar to habitat used by spawning salmonids. Across the entire Willamette Basin, Pacific Lampreys appeared to select reaches with alluvial geology, likely because this is where gravel suitable for spawning accumulated. At the tributary scale, spawning patterns were not as strong, and in reaches with nonalluvial geology redds were more spatially clumped than in reaches with alluvial geology. These results can be used to help identify and conserve Pacific Lamprey spawning habitat across the Pacific Northwest.

Publication type Article
Publication Subtype Journal Article
Title Spawning patterns of Pacific Lamprey in tributaries to the Willamette River, Oregon
Series title Transactions of the American Fisheries Society
DOI 10.1080/00028487.2014.949013
Volume 143
Issue 6
Year Published 2014
Language English
Publisher Taylor & Francis
Contributing office(s) Coop Res Unit Seattle
Description 11 p.
First page 1544
Last page 1554
Country United States
State Oregon
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