Genetic Monitoring Reveals Genetic Stability within Threatened Chinook Salmon Populations in the Snake River

Identifying and understanding temporal genetic changes within fish populations has important implications for the management of those populations, especially ones with conservation concerns.  Such changes are often the result of genetic drift, which can be exacerbated when the size of a population decreases.  Using molecular genetics techniques, we monitored 17 Snake River Chinook salmon populations in Idaho and Oregon to determine how the genetic characteristics within the populations have changed over time, and how those characteristics may have been affected by supplementation efforts.  Levels of genetic diversity and effective population size estimates were calculated for samples collected over a 20 year time period, equating to a time span of about 4 generations.  Overall, we found stable levels of genetic diversity in most of the populations examined, despite the fact that many of the populations exhibited a significant decline in effective population size.  The lack of significant declines in these populations’ levels of genetic diversity is encouraging given their conservation status as a threatened species.