Changes in run timing and natural smolt production in a naturally spawning coho salmon (Oncorhynchus kisutch) population after 60 years of intensive hatchery supplementation

2006 ◽  
Vol 63 (10) ◽  
pp. 2343-2355 ◽  
Author(s):  
Michael J Ford ◽  
Howard Fuss ◽  
Brant Boelts ◽  
Eric LaHood ◽  
Jeffrey Hard ◽  
...  
Keyword(s):  
Natural Population ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Relative Fitness ◽  
Stabilizing Selection ◽  
Average Value ◽  
Significant Difference ◽  
Hatchery Supplementation ◽  
Run Timing

Supplementing natural fish populations with artificially propagated (hatchery) fish is a common practice. In evaluating supplementation, it is important to assess the relative fitness of both hatchery-produced and naturally produced fish when they spawn together in the wild and to evaluate how the absolute fitness of the natural population changes after many generations of supplementation. We evaluated the relative fitness of naturally produced and hatchery-produced coho salmon (Oncorhynchus kisutch) in Minter Creek, Washington, USA. We also evaluated long-term changes in natural smolt production in this stream after several decades of intensive hatchery supplementation. Total smolt production was estimated to be 14 660 and 19 415 in 2002 and 2003, respectively, compared with the average value of 28 425 from 1940 to 1955. We found no significant difference in relative fitness between hatchery and natural fish, probably because the natural population consists largely of fish produced from the hatchery a generation or two previously. There has been a long-term trend for adults to return to the stream earlier in the spawning season. We estimated standardized selection differentials on run timing, with results indicating stabilizing selection with an optimum run timing later than the mean contemporary run timing but earlier than the historical mean run timing.

Selection for Adult Size in Female Coho Salmon (Oncorhynchus kisutch)

1986 ◽  
Vol 43 (10) ◽  
pp. 1946-1959 ◽  
Author(s):  
L B. Holtby ◽  
M. C. Healey
Keyword(s):  
Coho Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Kisutch ◽  
Selective Advantage ◽  
Evolutionary Stable Strategy ◽  
Relative Fitness ◽  
Female Size ◽  
Adult Size ◽  
Stable Strategy ◽  
Wide Range

Several recent studies have presented evidence that large size confers a selective advantage to female Pacific salmon. Nevertheless, a wide range of female sizes is normally present in any spawning population. Two possible explanations exist for the observed range in female size. First, average female size might be determined by an optimizing process with variation around the optimum size due to individual differences in success at obtaining food. Second, various sizes of females might coexist as a mixed evolutionary stable strategy. Under the first explanation, females of sizes other than the optimum would display lower fitness whereas, under the second explanation, females of all sizes would be equally fit. We investigated factors affecting survival of eggs, fry, and smolts of coho salmon (Oncorhynchus kisutch) in Carnation Creek on Vancouver Island with a view to determining the relative fitness of different sized females. Egg-to-fry mortality was best explained by a model that included only the effects of stream bed scour and gravel quality. Including an effect of female size, expressed through depth of egg burying, worsened the model's predictive capability. We could find no evidence that the eggs of large females consistently survived better during incubation than those of small females. In fact, we observed three instances in which it appeared that the eggs of small females survived better. In Carnation Creek, large 1- and 2-yr-old smolts did not consistently survive better in the marine environment than small smolts. Thus, we were unable to demonstrate that the reproductive success of large females was consistently higher than that of small females, contrary to the hypothesis that female size is the result of an optimizing process. In Carnation Creek the observed range of female sizes probably represents an evolutionary stable strategy in which all sizes have equal fitness. We propose a model that predicts female size and variance in size based on the conflicting selective effects of gravel quality, scour, and competition for nest sites.

Long-Term Peripheral Treatment of Immature Coho Salmon (Oncorhynchus kisutch) with Human Leptin Has No Clear Physiologic Effect

2000 ◽  
Vol 118 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Dianne M. Baker ◽  
Donald A. Larsen ◽  
Penny Swanson ◽  
Walton W. Dickhoff
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Physiologic Effect

Survival, Contribution, and Return of Hatchery Coho Salmon (Oncorhynchus kisutch) Released into Freshwater, Estuarine, and Marine Environments

1991 ◽  
Vol 48 (2) ◽  
pp. 248-253 ◽  
Author(s):  
Mario F. Solazzi ◽  
Thomas E. Nickelson ◽  
Steven L. Johnson
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Columbia River ◽  
Fold Increase ◽  
Coast Guard ◽  
Control Group ◽  
Survival Index ◽  
Significant Difference ◽  
Columbia River Plume ◽  
Brood Fish

We released six groups of marked yearling hatchery coho salmon (Oncorhynchus kisutch) in six locations each year for five years beginning with the 1981 brood. Fish were released immediately below Bonneville Dam (control), at the Tongue Point Coast Guard Station (head of saltwater intrusion in the Columbia River), between the jetties at the Columbia River bar, in the Columbia River plume water, in coastal water approximately 19 km north and 19 km offshore of the mouth of the river, and in oceanic water approximately 38 km offshore. We found a 1.6-fold increase in the survival index (ocean catch through September 18 each year) for the fish released at Tongue Point compared with the control group. After adjusting for differences in the survival index between release groups, we found a 2.5-fold increase in the contribution to the Columbia River gillnet fishery from the fish released at Tongue Point compared with the control group. We found no significant difference between survival of the other release groups and survival of the control group. We also found that the percentage of adult fish that returned to locations other than the Columbia basin increased as the distance the fish were transported offshore increased.

Effect of Diets Containing Herring Oil Oxidized to Different Degrees on Growth and Immunocompetence of Juvenile Coho Salmon (Oncorhynchus kisutch)

1988 ◽  
Vol 45 (12) ◽  
pp. 2187-2194 ◽  
Author(s):  
Ian Forster ◽  
David A. Higgs ◽  
Gordon R. Bell ◽  
B. S. Dosanjh ◽  
B. E. March
Keyword(s):  
Growth Rate ◽  
Coho Salmon ◽  
Vibrio Anguillarum ◽  
Oncorhynchus Kisutch ◽  
Dietary Treatment ◽  
Feed Conversion ◽  
Oxidized Oil ◽  
Significant Difference ◽  
Antibody Titres ◽  
Dietary Treatments

Growth rate and efficiency of feed conversion were reduced by inclusion of oxidized herring oil in the diet, presumably as a result of reduced digestibility of the oxidized oil and suboptimal dietary concentrations of ω3 fatty acids. There was no evidence of any toxic factors in the oxidized oil. There was no significant difference in growth rate or the efficiency of feed conversion between juvenile coho fed diets supplemented with 30 and 1030 IU vitamin E/kg. Dietary treatment did not affect haematocrit values. Immunocompetence, judged by antibody titres in response to vibrio vaccination, was similar for all treatments. Disease resistance, assessed by the rate of mortality induced by exposure of nonvaccinated fish to challenge with Vibrio anguillarum or V. ordali, was likewise unaffected by the dietary treatments.

Experimental Confirmation of the Olfactory Hypothesis with Homing, Artificially Imprinted Coho Salmon (Oncorhynchus kisutch)

1976 ◽  
Vol 33 (4) ◽  
pp. 703-710 ◽  
Author(s):  
Jon C. Cooper ◽  
Allan T. Scholz ◽  
Ross M. Horrall ◽  
Arthur D. Hasler ◽  
Dale M. Madison
Keyword(s):  
Lake Michigan ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Spawning Migration ◽  
Experimental Confirmation ◽  
Olfactory Memory ◽  
Paired Group ◽  
Low Concentrations

To test the olfactory hypothesis of salmon homing, fingerling coho salmon (Oncorhynchus kisutch) were exposed to low concentrations of an odorous synthetic chemical, morpholine during presmolt and smolting periods. Equal numbers of these fish were not exposed (controls). Both groups were stocked directly into Lake Michigan near Oak Creek, South Milwaukee Wisconsin. Another paired group of exposed and unexposed fish was released 13 km north of Oak Creek. During the adult spawning migration 18 mo later, morpholine was dripped into Oak Creek and the returning salmon were censused.For four experiments over 2 consecutive yr, the number of exposed and unexposed fish captured at the artificially scented stream were, 216 vs. 28, 437 vs. 49, 647 vs. 65, and 439 vs. 55. These differences were highly significant (P <.001).During the 3rd yr, morpholine was not added to the stream during the spawning migration and exposed and nonexposed fish returned in equal, low numbers (51 vs. 55, P >.05). These results confirm the existence of odor imprinting and long-term olfactory memory in coho salmon, It is possible that this mechanism is also used in the natural imprinting situation.

The influence of family-correlated survival on Nb/N for progeny from integrated multi- and single-generation hatchery stocks of coho salmon (Oncorhynchus kisutch)

2007 ◽  
Vol 64 (9) ◽  
pp. 1258-1265 ◽  
Author(s):  
G R Moyer ◽  
M S Blouin ◽  
M A Banks
Keyword(s):  
Coho Salmon ◽  
Adult Stage ◽  
Oncorhynchus Kisutch ◽  
Parentage Analysis ◽  
Effective Population ◽  
Single Generation ◽  
Marine Life ◽  
A Value ◽  
Significant Difference ◽  
Few Data

There exist surprisingly few data on the final variance and mean of family sizes for hatchery-born fish at the adult stage. Thus, it is difficult to predict, for a conservation hatchery operation that minimizes the variance in progeny number, how much lower the true effective population size (Ne) of a cohort of hatchery-born adults will be than Ne predicted simply by the number of parents that produced them. We used parentage analysis to estimate the survival and Ne for two integrated stocks of hatchery coho salmon (Oncorhynchus kisutch). One hatchery is a multigeneration stock obtained by spawning 70% hatchery with 30% naturally reproducing fish, whereas the second is a single-generation stock derived from naturally reproducing coho. There was no significant difference in average overall survival between stocks, but observed Ne was significantly less than expected for each stock. Family-correlated survival contributed to roughly a 20% reduction in Ne over the freshwater and marine life stages. This reduction is similar to previous estimates and suggests a value that can be used when estimating the effective number of hatchery parents in applications of the Ryman–Laikre formula (at least for programs such as ours that attempt to equalize sex ratios and family sizes).

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