Session: Contributed
Presentation Title: Estimating Freshwater Survival of Juvenile Salmonid Hatchery Releases:
A Case Study in the Use of PIT Tags and Radio-Tags
Presenter Name: David M Hand
David M Hand*, Brian Davis, and Jennifer Poirier. U. S. Fish and Wildlife Service, Columbia
River Fisheries Program Office.
*Presenting author: david_hand@fws.gov, 360-604-2518
Abstract Text: We used Passive Integrated Transponder (PIT) tags to establish a long-term
monitoring program to estimate the apparent survival of juvenile spring Chinook salmon from
hatchery release downstream to Bonneville Dam, in the Columbia River. Data was used to
evaluate the effectiveness of various release strategies, identify migration patterns of fish from
the hatchery, and provide information to hatchery managers on possible ways to increase
juvenile survival. Over the seven years of our evaluations, juvenile survival ranged from 30% to
60%. In an effort to provide more fine-scale survival information, we also developed a radiotelemetry project to estimate juvenile survival in the tributaries upstream of Bonneville Dam.
Tributary survival ranged from 42% to 85%, and may not necessarily track the survival patterns
we saw downstream to Bonneville Dam. In this presentation, we will discuss the development of
our study design, including simulation models used to determine appropriate sample sizes,
consideration of technology (radio-tags versus PIT tags), and how we decided to allocate our
efforts to increase the precision of our estimates. A comparison of our pre-study modeling
efforts to our actual study results will be presented, with a discussion of mistakes that were made
and lessons that were learned. We will also highlight other factors to consider when
implementing survival studies, such as project objectives, cost, types of technology, desired
precision levels, and consideration of potential tag effects.
Oral Presentation