Survival of Juvenile Chinook Salmon during Barge Transport

Abstract

To estimate survival during barge transport over a distance of 470 km from Lower Granite Dam on the Snake River to a release area downstream of Bonneville Dam (the lowermost dam on the Columbia River), we used a novel adaptation of a release–recapture model with 1,494 acoustic-tagged yearling Chinook salmon Oncorhynchus tshawytscha smolts. Smolts were collected at Lower Granite Dam, received surgically implanted acoustic transmitters, and were divided into three groups: (1) a barge group (R_B ) that was released into the raceway with fish that were later loaded into transportation barges (general barge population); (2) a control group (R_A ) that was held in a net-pen suspended within the barge hold containing the general barge population until 5–6 h prior to barge evacuation (i.e., fish release into the river), at which time they were confirmed to be alive and then released into the barge hold; and (3) a dead group (R_D ) that was euthanized and then released into the barge hold 5–6 h prior to barge evacuation in order to validate a model assumption. Six replicates of each group were loaded onto fish transport barges that departed from Lower Granite Dam between 29 April and 13 May 2010. Detections on acoustic receiver arrays between 70 and 220 km downstream of the barge evacuation site served as the basis for estimation of survival within the barge. The ratio of R_B : R_A survival from release to river kilometer 153 provided the estimate of within-barge survival. The replicate survival estimates ranged from 0.9503 ( = 0.0253) to 1.0003 ( = 0.0155). The weighted average of the replicate estimates of survival during the barge transportation experience was 0.9833 ( = 0.0062). This study provides the first active telemetry documentation that the assumed survival rate of 98% during the barge transportation experience appears to be justified for yearling Chinook salmon smolts.

Received March 4, 2011; accepted August 30, 2011

ACKNOWLEDGMENTS

We thank Blaine Ebberts, Derek Fryer, Dean Holecek, John Bailey, and Mike Halter (U.S. Army Corps of Engineers) for the funding, technical input, and support required to complete this work. We are also grateful to Fred Mensik and Shawn Rapp (Washington Department of Fish and Wildlife) for their help with smolt collection. A large number of dedicated staff members at the Pacific Northwest National Laboratory, including George Batten, Brian Bellgraph, Jessica Carter, Alison Colotelo, Susan Ennor, Andrew Gingerich, Ben Goodman, Kate Hall, Kenneth Ham, Ryan Harnish, Mike Hughes, Sara Kallio, Jina Kim, Eric Oldenburg, Lori Ortega, Mike Parker, John Stephenson, Donna Trott, Ricardo Walker, and Christa Woodley, helped with fish collection, tagging, fish transport, releases, receiver deployment, data processing, analyses, and editing. Brenda James and others at Cascade Aquatics activated and delivered the acoustic transmitters. Net-pens were loaned to us for this project by Frank Loge (University of California–Davis). This paper benefitted from reviews by Billy Connor, Doug Marsh, Stephen Riley, and an anonymous reviewer.