Effectiveness of Common Fish Screen Materials to Protect Lamprey Ammocoetes

Abstract

Understanding the effects of irrigation diversions on populations of Pacific lamprey Lampetra tridentata in the Columbia River basin is needed for their recovery. We tested the effectiveness of five common fish screen materials for excluding lamprey ammocoetes: interlock (IL), vertical bar (VB), perforated plate (PP), and 12-gauge and 14-gauge wire cloth (WC12) and (WC14). When fish (28–153 mm) were exposed for 60 min to screen panels perpendicular to an approach velocity of 12 cm/s in a recirculating flume, the percentage of ammocoetes entrained (i.e., passed through the screen) was 26% for the IL, 18% for the PP, 33% for the VB, 62% for the WC14, and 65% for the WC12 screens. For all screens, most fish were entrained within the first 15–20 min. Fish length significantly influenced entrainment, with the PP, VB, and IL screens preventing fish greater than 50–65 mm from entrainment and the WC14 and WC12 screens preventing entrainment of fish greater than 90–110 mm. Fish of all sizes repeatedly became impinged (i.e., contacting the screen for more than 1 s) on the screens, with the frequency of impingement events increasing during the first 5 min and becoming relatively stable thereafter. Impingement ranges were highest on the IL screen (36–62%), lowest on the WC14 and WC12 screens (13–31%), and intermediate on the PP and VB screens (23–54%). However, the WC14 and WC12 screens had fewer and larger fish remaining as time elapsed because so many were entrained. For all screen types, injuries were rare and minor, and no fish died after overnight posttest holding. Our results indicate that wire cloth screens should be replaced, where practical, with perforated plate, vertical bar, or interlocking bar screens to reduce lamprey entrainment at water diversions.

Received October 26, 2011; accepted March 14, 2012

ACKNOWLEDGMENTS

We thank Aaron Jackson of the Confederated Tribes of the Umatilla Indian Reservation, Jody Brostrom and Dan Shively of the U. S. Fish and Wildlife Service, Sue Camp and Ron Eggers of the U. S. Bureau of Reclamation, and Bob Heinith and Brian McIlraith of the Columbia River Intertribal Fish Commission for technical and financial assistance. For technical advice and coordination with the Fish Screen Oversight Committee we thank Michael Lambert, Ray Hartlerode, Ken Frisby, and Alan Ritchey of the Oregon Department of Fish and Wildlife; Patrick Schille and Chuck Lenberg of the Washington Department of Fish and Wildlife; and David Ward of the Columbia Basin Fish and Wildlife Authority. For editorial and laboratory assistance we recognize Chris Dixon, Gabriel Hansen, Joe Warren, and Lisa Weiland of the Columbia River Research Laboratory. Comments by David Geist and two anonymous reviewers improved the manuscript. Reference to trade names does not imply endorsement by the U.S. Geological Survey.