populations of spring chinook salmon in the subbasins of the upper Willamette
River are genetically similar to the wild populations in these basins and
should continue to be used for recovery of spring chinook salmon.
the conclusion of a study published in July by Oregon Department of Fish and
Wildlife researchers. The research had been identified as high priority by the
2008 Willamette Project biological opinion. Spring chinook salmon of the upper
Willamette River basin were first listed in 1999 as threatened under the U.S.
Endangered Species Act, a label that had been reaffirmed in 2005 and again in
to this study the genetic relationships between hatchery and wild chinook
salmon in the basin were unknown. The study’s results lend confidence to the
current approach for recovery of spring chinook salmon in the upper Willamette
sub-basins of the upper Willamette River, hatchery spring chinook appear to be
closely related to the local wild populations, with similar or higher levels of
genetic diversity,” said Marc Johnson, technical analyst for the Oregon
Department of Fish and Wildlife, ODFW Corvallis Research. “Populations among
most Willamette subbasins are slightly, but significantly, different from one
article was published in the North American Journal of Fisheries Management, http://afs.tandfonline.com/doi/abs/10.1080/02755947.2014.920739#.VBL3VPldVrM.
authors are Johnson and Tom Friesen, program manager for ODFW Upper Willamette
Salmonid Research, Monitoring and Evaluation, ODFW Corvallis Research Lab.
study further concludes that spring chinook salmon that originate in Upper
Willamette River hatcheries “represent appropriate founder populations for
ongoing reintroduction programs and recommend that the conservation and
recovery of this stock proceed through management actions developed
specifically for each sub-basin.”
the same time, the authors recommend that restrictions on hatchery stock
transfers within the subbasins of the upper Willamette River continue in order
to preserve the genetic structure of the current populations, which is
currently a part of the recovery plan for the salmon. According to Johnson, the
“Conservation and Recovery Plan authored by ODFW and NOAA recommended treating
each subbasin as a unique population, each with its own criteria for recovery.”
in the Upper Willamette River have impeded the movement of juvenile and adult
salmon in the basin and five state-operated hatcheries are releasing
significant numbers of juveniles into the streams of the basin to mitigate for
this lost habitat. That could pose a threat to the wild populations if hatchery
populations are less diverse.
the genetic relationships between hatchery and wild spring chinook salmon
stocks had not been shown in previous research, the authors weren’t surprised
by this study’s findings since the hatchery brood-stocks were founded by local
stocks and hatcheries had historically included some wild fish into the brood.
In fact, they found that the hatchery populations are most genetically similar
to the local wild populations from the same subbasin.
observed that most of the genetic diversity in upper Willamette chinook salmon
could be found in every population, represented by multiple alleles within and
among individuals of each population,” Johnson said. “Moreover, our findings
were consistent with those of a previous study, which together suggest that
upper Willamette spring Chinook present high levels of heterozygosity and
allelic richness, relative to other Columbia River populations.”
richness is defined by Johnson as the per capita number of alleles (for a
particular locus) in a population of organisms. High allelic richness implies a
larger pool of genetic variation to allow future adaptation. Heterozygosity is
a measure of genetic diversity within individuals, characterized by the
presence of different alleles at a given genetic locus.
factors other than genetic makeup can affect the productivity of salmon
the Willamette hatchery programs appear to be effective at maintaining
demographically robust and genetically diverse salmon populations, we cannot
assume that they produce fish that are well-suited to survive and reproduce in
the wild,” Johnson said. “The reproductive success of Willamette hatchery chinook
in the wild is the subject of ongoing research by Oregon State University, and
information from that work will undoubtedly help managers to chart the best
course to recovery for this stock.”
releases of hatchery juveniles have failed to result in “wild adult returns
despite apparently substantial natural production of juveniles,” the report
results underscore both the potential of hatchery-origin fish for local
reintroduction programs and the fundamental role that improved dam passage must
play to secure the long-term viability of spring chinook salmon in the upper
Willamette River,” the report concludes.