Geochemical Analysis of Fin Rays to Identify Chinook Salmon Populations in the Wenatchee Basin Using Inductively Coupled-Mass Spectrometry
EMSL Project ID
47696
Abstract
The goal of this project is determine whether it is possible to identify adult spring Chinook salmon returning to White River, Chiwawa River and Nason Creek in the Wenatchee River basin by geochemical analysis of fin rays. The major assumption in this analysis is that variation in water chemistry among these streams produces an elemental or isotopic signature in these structures during the period of juvenile residence that is retained in whole or in part in the adult salmon as they migrate back to their natal river to spawn. Secondly, these signatures must be stable enough through time to ideally permit basin of origin assignment of adult salmon using geochemical data from juvenile fish of the same cohort. Preliminary studies indicate that geochemical variation in scale and fin ray samples among these rivers provides sufficient discriminating power to identify unknown fish. However, the results are based on small sample sizes with considerable variation in the elemental composition in scales within and among (adult) fish and rivers. This variability appears to be related, in part, to differential reabsorption of scale calcium during maturation. These findings reflect important information needs for identifying stable geochemical signatures that can be used to correctly assign adult spring Chinook salmon to their basin of origin. The second phase of this project is designed to address these needs through more detailed analysis of the relation between river water and juvenile salmon geochemistry, and the persistence of these signatures in adult fish. The specific questions and the chronological order in which we will attempt to answer them are:
1. Do elemental concentrations or isotope ratios differ significantly among rivers?
2. Are these differences temporally stable?
3. Do these signatures appear in juvenile salmon and are they found in the approximate concentrations and ratios as those in the natal streams?
4. If so, do juvenile geochemical signatures persist in adult salmon? If not, are there other signatures (e.g. structural elements such as P or 43Ca/40Ca) that can discriminate among adult salmon?
5. Are the elemental or isotopic differences great enough and can they be routinely detected with sufficient accuracy and precision to correctly assign ?90% of adult salmon to their basin of origin.
We believe this approach will provide a systematic framework to determine whether geochemical signatures can be used to correctly identify naturally spawning spring Chinook salmon returning to the Wenatchee River basin. This basin-of-origin information will give resource managers a valuable tool to make informed decisions regarding in-season abundance of these populations and, in the process, effectively aid in their recovery.
Project Details
Start Date
2012-11-12
End Date
2013-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)