Adult Recovery of Hatchery Spring Chinook Salmon Adipose Fin-Clipped and Coded-Wire-Tagged Using an Automated and Manual Marking Trailer

Abstract

Marking and tagging fish is a critical component of many hatchery monitoring and evaluation programs, and coded wire tags are part of the foundation for managing Pacific salmon Oncorhynchus spp. Fin-clipping and coded-wire-tagging large numbers of juvenile salmonids is done either by hand or by using an automated tagging trailer system. We compared the hatchery adult recovery rate of spring Chinook Salmon O. tshawytscha marked and tagged as juveniles by manual and automated tagging trailers at Warm Springs National Fish Hatchery (NFH) and Carson NFH. At Warm Springs NFH, the adult recovery rate for fish marked in the automated trailer was 0.16%, compared with a recovery rate of 0.14% for fish marked in the manual trailer. A fish was 1.17 times more likely to be recovered as an adult at the hatchery if marked in an automated trailer. Coded wire tag retention rates were more variable for manually marked fish. At Carson NFH, there was no difference in recovery rate or coded wire tag retention rate between marking trailers. These data suggest that the automated marking procedure does not reduce adult recovery rates from the time of marking to adult return when compared with manual marking. The lower recovery rate of manually marked fish at Warm Springs NFH may have been due to manual marker inexperience, use of anesthetic, or other factors. Additional information on the implications of differential coded wire tag retention and adult survival related to marking methods is necessary for hatchery managers to make decisions on how to mark and tag their fish.

Received February 4, 2014; accepted April 13, 2014

ACKNOWLEDGMENTS

The U.S. Fish and Wildlife Service's Columbia River Fisheries Program Office Marking Program was instrumental in implementing this evaluation. Jesse Rivera provided valuable coordination and advice in developing this study. Steve Pastor provided database support and summary data for the hatchery tagging and recovery components of the analysis, and Julianne Harris provided statistical advice and a review of an earlier draft of this manuscript. The staff at Carson and Warm Springs NFHs were extremely helpful in assisting in the collection and processing of the adult returns. We also appreciate the anonymous reviewers and journal editors who make the peer review process work. This study was supported through funding by the U.S. Fish and Wildlife Service and NOAA–Fisheries (Mitchell Act). Reference to trade names does not imply endorsement by the U.S. Government. The findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service.