Use of geochemical signatures to identify spawning ground locations of kokanee salmon (Oncorhynchus nerka) in Lake Roosevelt, WA
EMSL Project ID
48711
Abstract
Natural origin kokanee (Oncorhynchus nerka) make an important contribution to sport fisheries in Lake Roosevelt. The population is genetically distinct from nearby wild and hatchery populations in Canada and the U.S., and represents as much as 70% of the annual kokanee harvest in Lake Roosevelt. Fall surveys of rivers and streams that flow into Lake Roosevelt indicate that few of these fish migrate into tributaries to spawn, suggesting this population may principally utilize shore spawning areas within the lake as natal habitat. The location of this habitat, however, has yet to be identified, which has hindered effective management because the size of the spawning population is unknown. The purpose of this project is to identify these spawning grounds through geochemical analysis of kokanee otoliths (ear bones) and relate this information to similar analyses of lake water and samples of a benthic sentinel species (e.g. freshwater mussels) collected throughout the Lake Roosevelt basin. Studies have shown that chemical gradients in the lake water and sediments extend from the Canadian border to Grand Coulee Dam. These gradients differ among elements known to be taken up in otoliths, and may provide a chemical signature in kokanee otoliths as they move throughout the lake. Thus, when tied to the developmental chronology in the otolith, these chemical signatures can be used to map the spatial life history of kokanee in the lake and thereby approximate spawning ground location(s). The geochemical signatures will be identified, in part, by solution and laser ablation multi-collector inductively coupled mass spectrometry to measure 87Sr/86Sr ratios in water, mussel and otolith samples. One of these instruments (Thermo Fisher Neptune Plus) is an EMSL resource that we have previously used for this purpose (Linley, T., E. Krogstad, K. Carter, and M. Nims. 2014. Geochemical Analysis of Fin Rays to Identify Spring-Run Chinook Salmon Populations in the Wenatchee Basin Using Inductively Coupled-Mass Spectrometry. Final Report to the Priest Rapids Coordinating Committee. Report No. PNWD-4412. 32 p.). Access to this instrument will provide us and the client (Confederated Tribes of Colville Reservation) with critical information about 87Sr/86Sr ratios in the Lake Roosevelt ecosystem and aid importantly in identifying the spawning habitat of kokanee salmon.
Project Details
Start Date
2015-03-20
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Linley TJ, EJ Krogstad, MK Nims, and RB Langshaw. 2016. "Geochemical signatures in fin rays provide a nonlethal method to distinguish the natal rearing streams of endangered juvenile Chinook Salmon Oncorhynchus tshawytscha in the Wenatchee River, Washington." Fisheries Research 181:234-246. doi:10.1016/j.fishres.2016.04.004