Effect of backwatering a streamgage weir on the passage performance of adult American Shad (Alosa sapidissima)

Abstract

Streamgage designs often include a full-width artificial hydraulic control (e.g., concrete weir) to aid in the computation of streamflow. While important to water resource managers, these weirs also tend to act as full or partial barriers to fish migration, effectively hindering the health and survival of these populations. In this study, we conducted experiments to quantify the effect of head drop and submergence of a common streamgage weir on the passage performance of an important migratory fish species, the American Shad. Three treatment conditions were selected based on the tailwater surface elevation (El_TW): unsubmerged (El_TW = 1.05 m; head drop = 0.46 m), equal to the weir crest (El_TW = 1.20 m; head drop = 0.31 m), and submerged (El_TW = 1.36 m; head drop = 0.15 m). Fish movements were recorded via passive integrated transponder telemetry techniques. Results revealed that the backwatered Columbus-type weir was not a complete barrier at any of the three treatments, but passage was shown to be significantly impaired when the weir was unsubmerged. Passage efficiency for the unsubmerged, equal, and submerged treatments was 20.2 ± 6.2, 49.2 ± 7.2, and 64.2 ± 7.4%. Backwatering a weir, rather than removal or other major alterations that would affect weir calibration, may be an acceptable retrofit to increase fish passage.

Keywords:

• Fish passage
• streamgage
• weir
• American Shad

Acknowledgements

Special thank you to current and former USGS employees Stephen Walk, Samuel Parker, Kevin Molongoski, and Kaila Woodson for their assistance with the American Shad collection, construction, data collection, video review, antenna construction, and more. Without their help, this work would not have been possible. Thank you to Adria Elskus and Bryan Sojkowski for a detailed and thorough review of this manuscript. Lastly, thank you to Holyoke Gas & Electric for access to their site and assistance with the American Shad collection.

Data

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Data supporting the conclusions can be obtained through the U.S. Geological Survey ScienceBase‐Catalog (https://doi.org/10.5066/P9YD69FV).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project was funded by the USFWS, North Atlantic‐Appalachian Region, Fish and Aquatic Conservation, National Fish Passage Program (Hadley, MA) and the USGS Northeast Region.