Genetic Monitoring Reveals Genetic Stability within and among Threatened Chinook Salmon Populations in the Salmon River, Idaho

Abstract

Identifying and understanding temporal genetic changes within fish populations is important for the management of these populations, especially those of conservation concern. 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 nine populations of Chinook salmon Oncorhynchus tshawytscha in the Salmon River, Idaho, to determine how the genetic characteristics within and among these populations have changed over time. We found no evidence of change in the level of heterozygosity or allelic richness over three to four generations in eight of the populations. This is probably due to the fact that the populations all maintained a sufficiently large effective size, even though a few of the populations did show a decline in effective size. Also, the genetic structure among the populations did not change appreciably over time. Populations that had been supplemented with hatchery‐reared fish showed genetic similarity to the within‐basin hatchery source population, presumably because of the extensive use of native fish for hatchery brood stocks and minimal out‐of‐basin stock transfers. The lack of a detectable decline in these populations’ levels of genetic diversity is encouraging, given the species’ threatened status under the U.S. Endangered Species Act.Received September 22, 2010; accepted December 8, 2010

Loss of genetic integrity in wild lake trout populations following stocking: insights from an exhaustive study of 72 lakes from Québec, Canada

“…; Van Doornik et al. ) and thus reinforce our interpretation that admixture found in stocked populations most probably resulted from stocking rather than from naturally occurring changes in genetic composition over time. Likewise, the high coherence between the well‐documented stocking intensity and the observed admixture of stocked populations reinforces our conclusions.…”

Little impact of hatchery supplementation that uses native broodstock on the genetic structure and diversity of steelhead trout revealed by a large‐scale spatio‐temporal microsatellite survey

“…Indeed, such temporal stability of genetic diversity is also characteristic of other, relatively unperturbed steelhead trout populations in BC (Heath et al. 2002; see also Van Doornik et al. 2011 for Chinook salmon, Oncorhynchus tshawytscha ).…”

“…One important potential impact of supportive breeding is that it may produce changes in the effective population size of supported populations by inducing variability in family size, especially in long‐term programs for organisms like salmonid fishes that are characterized by high fecundities (Ryman and Laikre 1991; Ryman et al. 1995; Van Doornik et al. 2011).…”

“…Given that many rivers throughout the southern mainland coast of BC have shown evidence of declines in the number of wild adult steelhead trout since about 1990 (Smith and Ward 2000; Ahrens 2004), our study serves to develop a baseline to monitor genetic change in rivers with declining numbers of wild spawners (cf. Van Doornik et al. 2011).…”

Intraspecific Relationships in Paracalanus quasimodo [Calinoideae] and Temora turbinata [Calinoideae] along the Southeastern Coast of the United States

“…Most studies find that the populations are stable and resilient to stressors such as population decline exacerbated by harvesting pressure (Cuveliers et al 2011;Van Doornik et al 2011). However, some species show a significant change in genetic signature over the course of the study, whether over generations (Larsson et al 2010) or over seasons (Dunton et al 2012).…”