The establishment of impoundments and operations associated with hydroelectric production and irrigation has modified the environment of native redband trout in the Upper Klamath River.  These modifications include fragmentation of habitats, obstruction of upstream and downstream passage, alteration of stream flows and water quality, and increased competition from introduced species associated with habitat changes.  An improved understanding of the life history of these trout populations is needed to address management concerns and guide dam operation protocols that minimize detrimental impacts to these populations. The Native Fish Investigations Project recently used radio telemetry and PIT-tag technology to monitor movement patterns.

Spencer Creek is a major spawning area and recruitment source of redband trout in the upper Klamath River. The confluence of Spencer Creek and the Klamath River is 1.5 km upstream of J.C. Boyle dam, which was built in 1959. Past studies provide evidence of a dramatic decline in adult upstream passage since the dam was built and relatively little juvenile downstream passage. However, sampling efforts to quantify the magnitude and extent of movements by juveniles to locations downstream of the dam were limited in scope. Operation of J.C. Boyle Dam may reduce the likelihood that juvenile redband trout from Spencer Creek can move downstream past the dam safely and efficiently and may reduce adult upstream passage to Spencer Creek. In order to better understand juvenile and adult redband trout life history and evaluate fish passage over J.C. Boyle dam, Native Fish Investigations Project monitored redband trout movement in Spencer Creek and the upper Klamath River during 2004 and 2005. We captured juvenile trout (>90 mm) as they emigrate from Spencer Creek and tagged them with inter-peritoneal radio transmitters (NanoTags, Lotek Wireless). Adults, upstream and downstream of the dam, were also radio tagged. Movements of radio-tagged fish were monitored using fixed-station receivers at locations associated with hydropower facilities and mobile receivers in free-flowing reaches. In addition, we marked several hundred outmigrating juvenile trout (>70mm) in Spencer Creek, and 50 adult trout in the Klamath River, with passive integrated transponder (PIT) tags and installed PIT-tag receiver stations at the mouth of Spencer Creek and downstream of J.C. Boyle Dam.

Upper Klamath Basin Genetics

Questions pertaining to redband trout population structure in the Upper Klamath Basin became evident during the evaluation of status of the Klamath River Redband Trout SMU for the 2005 Native Fish Status Review. The degree to which redband trout move among headwater streams, major rivers and the lake is virtually unknown. Biologists are uncertain if Upper Klamath redband trout should be considered as one large population, or if each spawning stream is a relatively isolated reproductive unit, or if some other population structure exists.

In addition questions regarding the distribution of the two major lineages still exist. Klamath Basin contains two subspecies of Oncorhynchus mykiss. O. mykiss irideus is a non-anadromous form that colonized the basin from the Pacific Ocean prior to dam construction on the lower river. The redband form, O. mykiss newberri, is present in the upper reaches above Klamath Falls. Historically Upper Klamath Lake had no outlet to the ocean and was an inland basin similar to other drainages in the Great Basin. Previous studies found that populations with access to the ocean formed one major lineage while fish in the headwaters of the Sprague River, Williamson River, and Jenny Creek formed a separate lineage. However, these studies used techniques less appropriate for fine population structure.

To address these questions the Native Fish Investigations Project is working with Devon Pearce at the Southwest Fisheries Science Center to analyze a collection of genetic samples collected throughout the Upper Klamath Basin. Our objectives are to identify distinct populations and lineages of O. mykiss and estimate the potential and ongoing gene flow among tributary reaches.

Annual Reports and Publications:

Summary of Initial Findings: 2004

Starcevich, S.J., S.E. Jacobs,  and W. Tinniswood.  2006.  Effects of dams on redband trout life history in the Upper Klamath River:  A summary and synthesis of past and recent studies.  Oregon Department of Fish and Wildlife, Information Report, Corvallis.

Pearse, D. 2007. Population genetics of Oncorhynchus mykiss in the Upper Klamath Basin.  Report of Devon Pearce, Southwest Fisheries Science Center to the Oregon Department of Fish and Wildlife, Corvallis, Oregon.

Jacobs, S.E., S.J. Starcevich, and W. Tinniswood. 2008. Effects of impoundments and hydroelectric facilities on the movement and life history of redband trout in the upper Klamath River: A summary and synthesis of past and recent studies. Pages 67-75 in R.F. Carline and C. LoSapio, editors. Sustaining wild trout in a changing world. Proceedings of the Wild Trout IX Symposium, Joseph Urbani & Associates, Bozeman, Montana.