Population Estimates of Sockeye Salmon (Oncorhynchus nerka) in a Fertilized Oligotrophic Lake

1978 ◽  
Vol 35 (6) ◽  
pp. 851-860 ◽  
Author(s):  
D. G. Robinson ◽  
W. E. Barraclough
Keyword(s):  
Survival Data ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Age Groups ◽  
Close Correlation ◽  
Oligotrophic Lake ◽  
Population Estimates ◽  
Good Resolution ◽  
Growth And Survival ◽  
Carry Over

Pelagic juvenile sockeye salmon (Oncorhynchus nerka) populations were studied in Great Central Lake, British Columbia, during 1969–76 to determine the effect of nutrient enrichment upon their growth and survival. Data for population estimates were collected concurrently by a high-frequency echosounder, and a midwater trawl whose efficiency was inversely related to ambient light above about 1.9 × 10−5 lx. Echogram counts supplemented by trawl catches yielded estimates with low variance, good resolution between age-groups, and indicated close correlation between numbers of spawners and resultant progeny within respective treatments. Survival to the fall for the treated 1969–72 brood years averaged 11.65% (range 11.11–12.81%) of potential egg deposition compared to 3.5% for the pretreatment 1968 brood year fish; 2.73 and 6.29% for the posttreatment 1974 and 1975 brood year fish. A carry-over of fertilization effects on the immediate posttreatment 1973 brood year may have induced a cyclic pattern on the survival of the two succeeding year-classes. The relatively consistent annual production of age 0+ sockeye may be due to the inherent stability of inlake spawning and incubation coupled with the low predation rates. The conservative estimate of a 2.5 increase in survival relative to the natural level indicates a positive response to enhanced feeding conditions caused by the fertilization of this oligotrophic lake. Key words: sockeye, survival, Great Central Lake, fertilization, enhancement, acoustic estimates, townet efficiency

Effects of population-specific variation in age and length on fishery selection and exploitation rates of sockeye salmon (Oncorhynchus nerka)

2009 ◽  
Vol 66 (6) ◽  
pp. 896-908 ◽  
Author(s):  
Neala W. Kendall ◽  
Thomas P. Quinn
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Age Groups ◽  
River System ◽  
Directional Selection ◽  
Size At Maturity ◽  
Natural Processes ◽  
Fishery Exploitation ◽  
Specific Variation ◽  
Complex Variation

Conspecific salmonid populations often differ in age and body size at maturity, and these differences can cause fishery exploitation rates and patterns of directional selection on size to vary among populations. Based on age and length data on five representative spawning populations of sockeye salmon ( Oncorhynchus nerka ) in the Wood River system, Bristol Bay, Alaska, USA, we estimated exploitation rates and population-specific patterns of selection from a gillnet fishery between 1963 and 2007. Exploitation rates have differed among age groups and have varied greatly over time, likely due to changes in fishery selectivity. Populations with older, larger fish were more heavily exploited than populations with small, young fish. Differential fishery selection was detected among the populations, linked to persistent differences in size and age of fish among the populations. Specifically, we found evidence of stronger size selectivity on populations with smaller-bodied fish and less directional selection on populations dominated by larger-bodied fish. These results reveal the complex variation in the intensity and selectivity of fishing that can result from exploitation of populations that differ in age and size at maturity and shape. Evolutionary responses to this selection may be taking place, but natural processes provide countervailing selection.

Mate Selection in a Population of Sockeye Salmon (Oncorhynchus nerka) of Mixed Age-groups

1967 ◽  
Vol 24 (9) ◽  
pp. 1955-1977 ◽  
Author(s):  
Arthur J. Hanson ◽  
Howard D. Smith
Keyword(s):  
Mate Selection ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Age Groups ◽  
Different Types ◽  
Skeena River ◽  
The Relationship ◽  
Mixed Age

Anadromous Skeena River sockeye mature and spawn mainly at ages 42 and 52. Lesser numbers of 32, 53, and 63 and 64 fish, and non-anadromous kokanee, may spawn in the same stream. Mate selection by the different types was studied by observing salmon of known length and using the relationship found between length and age in dead, spawned fish.Fish of all lengths tended to mate with similar sized fish. Small males were less successful in holding mates than were large males because they could not successfully defend redds against larger intruders. Small males spent more time alone than large ones and frequently lay in groups behind mating pairs. The term "satellite male" is used in describing the behaviour. Small females mated with large males but spent more time alone than did large females.The genetic implications of mating within age-groups are considered.

Comparison of Acoustic Population Estimates of Salmon in a Lake with a Weir Count

1986 ◽  
Vol 43 (7) ◽  
pp. 1373-1385 ◽  
Author(s):  
T. J. Mulligan ◽  
R. Kieser
Keyword(s):  
Sensitivity Analysis ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Target Strength ◽  
Population Estimates ◽  
Acoustic Methods ◽  
Acoustic Surveys

Acoustic population estimates are performed routinely in fisheries. Usually, however, they have to stand on their own merit. A unique opportunity has been exploited to compare a series of acoustic surveys with a weir count that monitors the escapement of sockeye salmon, Oncorhynchus nerka, into a lake. Each survey was analysed by three acoustic methods; the results are compared among themselves and with the weir count. A detailed sensitivity analysis looks at the possible variance and bias in each method. Finally, several methods are used to estimate the acoustic fish target strength. These estimates are compared with published target strength values.

Babine Lake Sockeye Salmon (Oncorhynchus nerka) Enhancement Program: Testing some Major Assumptions

1984 ◽  
Vol 41 (1) ◽  
pp. 70-92 ◽  
Author(s):  
J. McDonald ◽  
J. M. Hume
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Effective Means ◽  
Growth And Survival ◽  
Program Testing ◽  
Basic Assumptions ◽  
Before And After ◽  
Average Size ◽  
Before And After Study ◽  
Future Management

The objective of the Babine Lake sockeye salmon (Oncorhynchus nerka) enhancement project was to increase fry outputs (and thus, smolt outputs and adult returns) by expanding and improving available spawning beds through the use of artificial spawning channels and related water flow control facilities. The project proceeded on four basic assumptions: (1) the artificial spawning channels would prove an effective means of producing sockeye fry, (2) the fry produced would be as viable as those produced from natural spawning beds, (3) the lake nursery area had the capacity to support larger juvenile populations, and (4) increased smolt outputs would result in increased adult returns. A before and after study has allowed these assumptions to be tested. Egg-to-fry survival in the channels was close to 40%, as expected. Comparisons of wild and channel-produced fry did not reveal any substantial difference in their distribution, growth, and survival in the lake. Increases in the abundance of fry were followed by corresponding increases in the abundance of underyearlings in the lake and seaward migrating smolts. No significant change in the average size of the juveniles or their survival in the lake could be detected when population size increased. While the assumptions regarding juvenile production were found to be generally valid, adult returns did not meet expectations. This was due largely to the lack of response to increased smolt outputs from even-numbered brood years. Some options for future management are offered.

Resumption of anadromy or straying? Origins of Sockeye Salmon Oncorhynchus nerka in the Elwha River

2021 ◽  
Author(s):  
Thomas P. Quinn ◽  
George R. Pess ◽  
Ben J.G. Sutherland ◽  
Samuel J. Brenkman ◽  
Ruth E. Withler ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Elwha River

Alternative Recruitment Models of Adams River Sockeye Salmon, Oncorhynchus nerka

1987 ◽  
Vol 44 (9) ◽  
pp. 1551-1561 ◽  
Author(s):  
Jeremy S. Collie ◽  
Carl J. Walters
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Status Quo ◽  
Management Policy ◽  
Best Management ◽  
Interaction Terms ◽  
Ricker Model ◽  
The Status ◽  
Stock Recruitment ◽  
High Yields

Despite evidence of depensatory interactions among year-classes of Adams River sockeye salmon (Oncorhynchus nerka), the best management policy is one of equal escapement for all year-classes. We fit alternative models (Ricker model and Larkin model) to 32 yr of stock–recruitment data and checked, using simulation tests, that the significant interaction terms in the Larkin model are not caused by biases in estimating the parameters. We identified a parameter set (Rationalizer model) for which the status quo cyclic escapement policy is optimal, but this set fits the observed data very poorly. Thus it is quite unlikely that the Rationalizer model is correct or that the status quo escapement policy is optimal. Using the fitted stock–recruitment parameters, we simulated the sockeye population under several management policies. The escapement policy optimal under the Ricker model is best overall because of the high yields if it should be correct. If the three stock–recruitment models are equally likely to be correct, the simulations predict that adopting a constant-escapement policy would increase long-term yield 30% over the current policy and that an additional 15% increase in yield could be obtained if the policy were actively adaptive.

Reduced growth in wild juvenile sockeye salmon Oncorhynchus nerka infected with sea lice

2017 ◽  
Vol 91 (1) ◽  
pp. 41-57 ◽  
Author(s):  
S. C. Godwin ◽  
L. M. Dill ◽  
M. Krkošek ◽  
M. H. H. Price ◽  
J. D. Reynolds
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Sea Lice

Validation of daily increments and a marine-entry check in the otoliths of sockeye salmon Oncorhynchus nerka post-smolts

2015 ◽  
Vol 87 (1) ◽  
pp. 169-178 ◽  
Author(s):  
C. Freshwater ◽  
M. Trudel ◽  
T. D. Beacham ◽  
C.-E. Neville ◽  
S. Tucker ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Daily Increments
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