WSP04588

• File Number: 8220.101.10.A
• Description: Colorado River-Water Projects-Glen Canyon Dam/Lake Powell-Glen Canyon Adaptive Management-AMWG
• State: AZ
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/3/2004
• Title: AMWG Meeting Attachments-March 3-4 2004-Humpback Chub Methods Review
• Water Supply Pro - Doc Type: Report/Study

,

As an overview, the five charges presented in the Scope of Work and the Panel's findings
are paraphrased in the following'.

1. Are methods used in the Grand Canyon appropriate for determining status and
trends of the humpback chub population there?
The ASMR model is a variant of well-established and proven approaches. Its purpose is to
reduce the bias in abundance estimates by accounting for changes in both juvenile and adutt
vulnerabilities to capture as adults move into or out of the LCR, and to utilize information on
survivat from previous tagging in estimation of capture probabilities for each year. The ASMR
method acconnts for those dynamics, but can be improved to remove potential biases due to
additional sources of variation in capture probabilities.

2. Are Upper Basin methods appropriate for use in the Grand Canyon?
The ASMR is most appropriate for the Grand Canyon work because it takes advantage of
spawning aggregations in the LCR and efficiently uses the extensive data collected over a longer
period of sampling there. Work in the Upper Basin is limited by the shorter time series, less
extensive sampling, and the consequent constraint on providing estimates of recruitment,
mortality ratcs, and/or trend in abundance. As more data become available in the Upper Basin
studies, more complex modets such as the ASMR can be applied. Upper Basin methods should
not replace those currently employed in the Grand Canyon. There is no compelling scientific
reason to change the basic spring sampling schedule for Grand Canyon/LCR work to a fall
schedule. Doing so might create more problems than solutions,

3. Are there ways to improve methods used in the Grand Canyon work?
The Panel encourages consideration of tetemetry approaches to address questions about migration
to and from the LCR, use of simutation studies to evaluate potentiat biases in ASMR population
estimates, and recommends that results from well-established open population age-structured
methods (Jolly-Seber models) be compared to results from the ASMR modets. Similar analyses
of Upper Basin closed modet methods will atso be informative.

4. Do Grand Canyon methods provide rigorous data pertinent to llBC Recovery
Goals?
The ASMR method is appropriate for getting estimates of abundance, population growth rate
(i.e., trend), and recruitment, if assumptions about capture probabilities are reasonable. Upper
Basin methods do not provide as much information about these three criteria because of much
lower capture rates. In both cases, the Panel recommends that emphasis be placed on estimates of
poputation growth rate in determining if a population is to be down-listed or de-listed,

5. Are the current methods providing scientifically rigorous data to inform
decisions of the Glen Canyon Adaptive Management Program's Adaptive
Management Work Group?
Yes, Given the current constraints to work in Grand Canyon, the Panel views the basic structure
of the ASMR model as the appropriate approach. Several potentiat enhancements in the approach
should be pursued.

, Copied verbatim from the final report of the BBC Independent Review Panel Report to
the AMWG - Dec. 5, 2003