24 April
Ken Warheit
Director, Molecular Genetics Laboratory, Washington Department of Fish & Wildlife
Genetic Structure of Kokanee (Oncorhynchus nerka) Spawning in Tributaries of Lake Sammamish, Washington
Abstract
Kokanee are the non-anadromous freshwater form of Oncorhynchus nerka, and are native to the Lake Washington/Lake Sammamish watershed. Historically, this watershed supported three kokanee run-types: early-run from Issaquah Creek, now extinct; middle-run from the Sammamish River tributaries, now considered to be residualized sockeye; and late-run from the Lake Sammamish tributaries (Lewis, Ebright, and Laughing Jacobs Creeks). Since 1996, escapement for the late-run kokanee has been variable but low, which has prompted resource agencies to propose a hatchery-based augmentation program. We used microsatellite DNA and mtDNA (cytochrome b) sequences to determine the genetic structure among kokanee collections (primarily years 2000, 2001, and 2003) from Lewis, Ebright, and Laughing Jacobs Creeks, with the intent to use these data to help design the hatchery-based augmentation program. Preliminary analyses indicated that there was significant population differentiation among these three creeks, however, the analyses proved to be anything but straightforward. Several collections were in genetic disequilibrium, and samples collected in 2001 where significantly divergent at both the microsatellite and mtDNA markers from the 2000 and 2003 collections from the same tributaries. We show that several of the collections are actually aggregates composed of family groups and/or fish that appear to have originated from populations not included in our baseline (i.e., fish are either out-of-basin origin or sockeye). The year 2001 was unusual in that the fish appeared to have spawned randomly in both Lewis and Ebright Creeks, with respect to their creek of origin; however, fish that originated from Lewis Creek had a significantly different haplotype frequency than fish that originated in Ebright Creek. The genetic structure of kokanee populations associated with Lake Sammamish is affected by relatively low escapement, family groups, extreme inter-year variability in allelic and haplotypic frequencies, and possibly introgression with sockeye or kokanee populations from out-of-basin.
Bio
Ken Warheit received a Ph.D. in Integrative Bio/Paleontology from UC Berkeley in 1990, and has worked with the Washington Department of Fish and Wildlife since 1992. In 1996, Ken designed, initiated, and became the director of WDFW’s Wildlife Conservation Genetics program. In November 2005 WDFW created a single lead position for both the fish and wildlife genetics programs and appointed Ken as the Director of the WDFW Molecular Genetics Laboratory. Ken’s research program includes the development of statistical methods and models to investigate changes in the management of hatcheries and mixed-stock fisheries, as well as wildlife- and enforcement (forensics)-related genetic projects. Despite all this, Ken still maintains an interest in seabird morphometrics, paleontology, and evolution, and spends a good part of his day, with his wife and kids, raising cattle and horses.
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