Impacts of supplementation: genetic diversity in supplemented and unsupplemented populations of summer chum salmon (Oncorhynchus keta) in Puget Sound (Washington, USA)

2009 ◽  
Vol 66 (8) ◽  
pp. 1216-1229 ◽  
Author(s):  
Maureen P. Small ◽  
Ken Currens ◽  
Thom H. Johnson ◽  
Alice E. Frye ◽  
Jennifer F. Von Bargen
Keyword(s):  
Genetic Diversity ◽  
Chum Salmon ◽  
Isolation By Distance ◽  
Genetic Relationships ◽  
Puget Sound ◽  
Oncorhynchus Keta ◽  
Effective Population ◽  
Brood Stock ◽  
Census Size ◽  
Chum Salmon Oncorhynchus Keta

In supplementation programs, hatcheries employ wild-origin fish as brood stock and their offspring are allowed into wild spawning areas. Resource managers use supplementation to support imperiled salmonid populations, seeking to increase census size and possibly effective population size (Ne), while minimizing risks of genetic diversity loss and domestication from hatchery intervention. Here we document impacts of 5–10 years of supplementation on threatened summer-run chum salmon ( Oncorhynchus keta ) in Hood Canal (HC) and Strait of Juan de Fuca (SJF) in Washington State and compare them genetically with unsupplemented summer- and fall-run chum salmon from HC and South Puget Sound. Microsatellite allele frequencies identified four run-timing and geographic groups. HC and SJF summer chum salmon genetic relationships followed a metapopulation pattern of isolation by distance, similar to patterns prior to supplementation, suggesting that supplementation minimally impacted population structure. In most supplemented subpopulations, we detected no effects on diversity and Ne, but high variance in individual pairwise relatedness values indicated over-representation of family groups. In two subpopulations, hatchery impacts (decreased diversity and lower Ne) were confounded with extreme bottlenecks. Rebounds in census sizes in all subpopulations suggest that general survivorship has improved and that possible hatchery effects on genetic diversity will be overcome.

The influence of hydrographic structure and seasonal run timing on genetic diversity and isolation-by-distance in chum salmon (Oncorhynchus keta)

2008 ◽  
Vol 65 (9) ◽  
pp. 2026-2042 ◽  
Author(s):  
Jeffrey B. Olsen ◽  
Blair G. Flannery ◽  
Terry D. Beacham ◽  
Jeffrey F. Bromaghin ◽  
Penelope A. Crane ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Chum Salmon ◽  
Isolation By Distance ◽  
Geographic Distance ◽  
Population Connectivity ◽  
Oncorhynchus Keta ◽  
Chum Salmon Oncorhynchus Keta ◽  
Yukon River ◽  
Run Timing

We used 20 microsatellite loci to compare genetic diversity and patterns of isolation-by-distance among three groups of chum salmon ( Oncorhynchus keta ) from two physically distinct watersheds in western Alaska, USA. The results were consistent with the hypothesis that gene flow decreases as the complexity of the hydrographic system increases. Specifically, higher gene flow was inferred among 11 populations from a nonhierarchical collection of short coastal rivers in Norton Sound compared with 29 populations from a complex hierarchical network of inland tributaries of the Yukon River. Within the Yukon River, inferred gene flow was highest among 15 summer-run populations that spawn in the lower drainage, compared with 14 fall-run populations that spawn in the upper drainage. The results suggest that the complexity of the hydrographic system may influence population connectivity and hence the level of genetic diversity of western Alaska chum salmon. Finally, evidence of isolation-by-time, when controlling for geographic distance, supported the hypothesis that genetic divergence in Yukon River chum salmon is influenced by seasonal run timing. However, evidence of isolation-by-distance, when controlling for season run timing, indicated the populations are not sufficiently isolated, spatially or temporally, to prevent gene flow. Dispersal among summer- and fall-run populations may play a role in maintaining genetic diversity.

Size Selective Predation by Juvenile Chum Salmon (Oncorhynchus keta) on Epibenthic Prey in Puget Sound

1975 ◽  
Vol 32 (8) ◽  
pp. 1419-1429 ◽  
Author(s):  
Robert J. Feller ◽  
Victor W. Kaczynski
Keyword(s):  
Chum Salmon ◽  
Prey Selection ◽  
Puget Sound ◽  
Harpacticoid Copepod ◽  
Gut Contents ◽  
Oncorhynchus Keta ◽  
Size Spectrum ◽  
Natural Diet ◽  
Chum Salmon Oncorhynchus Keta ◽  
Juvenile Chum Salmon

Analysis of gut contents shows that juvenile (30–50 mm) chum salmon (Oncorhynchus keta) in Puget Sound select epibenthic organisms as their primary prey. Harpacticoid copepods numerically comprised over 80% of their natural diet in two areas studied, while terrestrial insects and cladocerans were most important in a third area. Calculation of Ivlev (1961) electivity coefficients indicated high selectivity factors for harpacticoids at one site (+0.59 to +0.94). Comparison of fish gut contents with quantitative epibenthic pump samples of available prey shows that prey selection was size related, but opposite that currently reported in the literature (e.g. Brooks and Dodson 1965); that is, the smaller of the available prey was preferred. This was true for both the total available prey size spectrum and the harpacticoid copepod fraction of the prey spectrum. Large numbers of prey eaten per fish suggest that juvenile chum salmon may exert high predation pressure on nearshore epibenthic organisms in Puget Sound during spring.

Early Marine Mortality of Marked Juvenile Chum Salmon (Oncorhynchus keta) Released into Hood Canal, Puget Sound, Washington, in 1980

1983 ◽  
Vol 40 (4) ◽  
pp. 426-435 ◽  
Author(s):  
Nicholas J. Bax
Keyword(s):  
Chum Salmon ◽  
Pink Salmon ◽  
Puget Sound ◽  
Oncorhynchus Keta ◽  
Daily Mortality ◽  
Chum Salmon Oncorhynchus Keta ◽  
Hood Canal ◽  
Time Period ◽  
Order Of Magnitude ◽  
Juvenile Chum Salmon

The average daily loss in numbers from a group of fluorescently marked, hatchery-reared, juvenile chum salmon (Oncorhynchus keta) remaining in the nearshore zone following their release from the hatchery into southern Hood Canal, Washington State, was estimated at 38–49%. This estimated loss was then adjusted by the estimated maximum emigration of marked fish from the sampling area and the average daily mortality over a 2- and a 4-d time period estimated at between 31 and 46%. These estimates are an order of magnitude higher than estimates of the average daily mortality of naturally emigrating juvenile pink salmon (O. gorbuscha) from the Bella Coola River, British Columbia, over a 40-d time period (Parker 1968). The two studies are contrasted and it is suggested that daily mortality is highly variable over the 40 d subsequent to saltwater entry, with mortality higher initially, particularly for those fish remaining close to their point of saltwater entry.

Mechanism and Occurrence of Focal Scale Resorption among Chum Salmon (Oncorhynchus keta) of the North Pacific Ocean

1989 ◽  
Vol 46 (7) ◽  
pp. 1147-1153 ◽  
Author(s):  
Brian Bigler
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Chum Salmon ◽  
North Pacific Ocean ◽  
Puget Sound ◽  
Oncorhynchus Keta ◽  
Chum Salmon Oncorhynchus Keta ◽  
The North ◽  
Scale Characteristic ◽  
The North Pacific

A recently documented scale characteristic of chum salmon (Oncorhynchus keta) originating from Hokkaido, Japan, has been found distributed almost exclusively among stocks of Asian origin. Scales from 10 544 chum salmon collected from 25 near-shore locations throughout the North Pacific Ocean were examined. Resorption of the scale focus, including instances where an easily visible hole had been formed, was found among 10.8% of Japanese chum salmon and 15.9% of chum salmon originating from the Soviet Union. In North America, this trait was infrequent (< 0.5%) among populations north of the Aleutian Islands, British Columbia, and Puget Sound, and was not found in Cook Inlet, Prince William Sound, and Southeast Alaska. Focal scale resorption arises from osteoclastic cellular activity, most likely following the first winter of life, and remains as a permanent mark thereafter. This unique, uniformly occurring, easily identifiable scale characteristic will provide a valuable tool for stock identification. Evidence of focal scale resorption is also reported in sockeye (O. nerka), coho (O. kisutch), and king salmon (O. tshawytscha), but was not found in pink salmon (O. gorbuscha), sampled from locations in Alaska.

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