Test fishery indices for sockeye salmon (Oncorhynchus nerka) as affected by age composition and environmental variables

2004 ◽  
Vol 61 (1) ◽  
pp. 80-92 ◽  
Author(s):  
Lucy Flynn ◽  
Ray Hilborn
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Average Error ◽  
Fishing Gear ◽  
Migration Route ◽  
Catch Per Unit Effort ◽  
Age Classes ◽  
Age Composition ◽  
Fishery Data ◽  
Average Body

In this paper, we explore sources of variability in test fishing indices for sockeye salmon (Oncorhynchus nerka) and illustrate potential solutions. For our analysis, we use the Port Moller test fishery in Bristol Bay, Alaska. The traditional model used to forecast run size using Port Moller test fishery data is based on a simple linear regression of total returns to the fishing districts against the cumulative test fishery catch-per-unit-effort (CPUE) index on a given date. We show that much of the inaccuracy of recent forecasts based on test fishery indices is due to the variable age composition of sockeye runs and the unequal vulnerability of respective age classes to the test fishing gear. We also illustrate solutions to the problems presented by variability in migration route and variability in return timing. In warmer years, we found that there was an increase in effective vulnerability to the test fishing gear and that the strength of this relationship increased linearly with the average body length of age classes. Retrospective analysis shows that correcting for age composition, migration route, and timing provides an in-season index of abundance with an average error of 6.7 million fish or 21%, compared with 33% for previous models.

A statistical model for in-season forecasts of sockeye salmon (Oncorhynchus nerka) returns to the Bristol Bay districts of Alaska

2005 ◽  
Vol 62 (7) ◽  
pp. 1665-1680 ◽  
Author(s):  
Saang-Yoon Hyun ◽  
Ray Hilborn ◽  
James J Anderson ◽  
Billy Ernst
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Bayesian Probability ◽  
Bristol Bay ◽  
Age Composition ◽  
Information Sets ◽  
Information Set ◽  
Fishery Data ◽  
Highest Posterior Density ◽  
Return Data

We developed a model for in-season age-specific forecasts of salmon returns using preseason return forecasts, age composition of in-season returns, cumulative in-season returns by fishing district, and age composition and an index of abundance from an in-season test fishery. We apply this method to the sockeye salmon (Oncorhynchus nerka) fishery in the Bristol Bay districts of Alaska. The model generates point estimates and Bayesian probability distributions for return numbers by age and river, and it provides an integrated framework for including all of the major data sources currently used in in-season forecasting. We evaluated model performance using early-season data from 1999–2001 and compared the effects of four information sets on forecast accuracy. The four information sets were as follows: I, district-specific inshore return data; II, inshore return data and test fishery data; III, inshore return data and preseason forecasts; IV, inshore return data, test fishery data, and preseason forecasts. Forecasts from information sets II, III, and IV were less biased than those from information set I. However, in terms of the forecast interval, forecasts from information set II were best because the 95% highest posterior density regions of forecasts from information set II covered the actual returns most frequently.

Limited behavioural thermoregulation by adult upriver-migrating sockeye salmon (Oncorhynchus nerka) in the Lower Fraser River, British Columbia

2009 ◽  
Vol 87 (6) ◽  
pp. 480-490 ◽  
Author(s):  
M. R. Donaldson ◽  
S. J. Cooke ◽  
D. A. Patterson ◽  
S. G. Hinch ◽  
D. Robichaud ◽  
...  
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Radio Telemetry ◽  
Oncorhynchus Nerka ◽  
Migration Route ◽  
Fraser River ◽  
Body Temperatures ◽  
Study Region ◽  
Ambient Temperatures ◽  
And Migration

The objective of this study was to combine radio telemetry with individual thermal loggers to assess the extent to which adult migrating sockeye salmon ( Oncorhynchus nerka (Walbaum in Artedi, 1792)) behaviourally thermoregulate during their migration through the Fraser River mainstem, British Columbia. The Fraser mainstem represents a region of the migration route that contains some of the highest mean temperatures encountered by sockeye salmon during their life history. We found that throughout the study area, individual sockeye salmon body temperatures occasionally deviated from ambient temperatures (ΔT), yet individuals maintained a ΔT of –1 °C or cooler for only 5% of their migration through the study region. There were moderate mean deviations of ΔT in two segments that are known to contain thermally stratified waters. In one of the study segments with the greatest ΔT, mean body temperatures decreased as river temperatures increased and ΔT became increasingly positive with higher river discharge rates, but these relationships were not observed in any of the other study segments. No relationship existed between ΔT and migration rate. While periodic associations with cool water were evident, mean body temperatures were not significantly different than mean river temperatures throughout the lower Fraser mainstem. This finding raises further conservation concerns for vulnerable Fraser River sockeye stocks that are predicted to encounter increasing peak summer river temperatures in the coming decades.

Fish age, nematode (Philonema oncorhynchi) infection, and development of sexual dimorphism by the adult male sockeye salmon, Oncorhynchus nerka, in western Alaska

1995 ◽  
Vol 73 (11) ◽  
pp. 1999-2004 ◽  
Author(s):  
Ole Kristian Berg ◽  
Chris J. Foote ◽  
Thomas P. Quinn
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Parasite Infection ◽  
Mature Male ◽  
Sexually Dimorphic ◽  
Age Composition ◽  
Body Depth ◽  
Duration Of Residence ◽  
Significant Difference ◽  
Seaward Migration

Of 255 mature male sockeye salmon (Oncorhynchus nerka) from two Alaskan lakes (Aleknagik and Iliamna), 254 (99.6%) were infected with the nematode Philonema oncorhynchi with a mean wet mass of 3.1 g (SD = 3.4 g) of nematodes. Fish that had spent 1 year in the lake prior to seaward migration had significantly lower parasite masses than those that had spent 2 years in the lake (2.7 vs. 4.1 g). However, there was no significant difference in parasite masses between lakes or among spawning populations within the lakes for fish of a given age or of all ages combined, even though the populations differed in age composition. The variation in relative parasite mass (mass of parasite (g)/mass of fish (kg)) was mainly explained by the significant variation in total mass of the parasites and the sea age of the fish. Thus, total parasite mass was correlated with the duration of residence in fresh water, while the relative parasite mass was correlated with fish size, and hence with the duration of residence in the sea. In spite of heavy infections (up to 28 g of nematodes) in many salmon, there were no corresponding reductions in mass/length or in the development of two sexually dimorphic features, body depth and snout length. Thus, parasite infection did not appear to affect traits under sexual selection, as hypothesized by Hamilton and Zuk.

Density-Dependent, Trophic Level Responses to an Introduced Run of Sockeye Salmon (Oncorhynchus nerka) at Frazer Lake, Kodiak Island, Alaska

1988 ◽  
Vol 45 (5) ◽  
pp. 856-867 ◽  
Author(s):  
G. B. Kyle ◽  
J. P. Koenings ◽  
B. M. Barrett
Keyword(s):  
Trophic Level ◽  
Sockeye Salmon ◽  
Inverse Relationship ◽  
Oncorhynchus Nerka ◽  
Density Dependent ◽  
Kodiak Island ◽  
Egg Plant ◽  
Threshold Length ◽  
Average Body Length ◽  
Average Body

Sockeye salmon (Oncorhynchus nerka) have developed into a major run at Frazer Lake, Kodiak Island, Alaska, reaching over 600 000 adults 34 yr after the first egg-plant in 1951. In the last nine years (1978–86), escapements have averaged over 250 000 with a record high of 486 000 adults in 1985. The increase in escapements were inversely related to seasonal macrozooplankton densities (p < 0.05; r2 = 0.42) but directly correlated with increases in the cladoceran to copepod ratio (p < 0.001). In addition, the average body length of the smallest macrozooplanker (Bosmina) has shifted below the observed threshold length of 0.40 mm for juvenile sockeye prey. We also found an inverse relationship between greater parental escapements and age 1. smolt length (p < 0.01; r2 = 0.75). Small-sized smolts produced from a density-dependent rearing environment indicate that spawning capacity equals or exceeds rearing capacity. Juvenile recruits from larger escapements (~400 000) exerted a controlling, density-dependent influence on the secondary trophic level which drastically reduced subsequent adult returns. Moreover, adverse trophic level changes, particularly after the largest escapements, also appeared to reduce the rearing efficiency for lower densities of juveniles, as subsequent smolt sizes from smaller escapements were less than expected. Thus, these findings not only provide a rationale for suggesting that fewer spawners would provide recruits more closely matching the rearing capacity of this lake, but also provide empirical evidence for the potential adverse density-dependent effects of large escapements.

Density and Distribution of Young Sockeye Salmon (Oncorhynchus nerka) throughout a Multibasin Lake System

1958 ◽  
Vol 15 (5) ◽  
pp. 961-982 ◽  
Author(s):  
W. E. Johnson
Keyword(s):  
Population Density ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Catch Per Unit Effort ◽  
Lake System ◽  
Unit Effort ◽  
Limited Dispersal ◽  
Discrete Populations

Estimates of density (based on catch per unit effort with tow nets) of fingerling sockeye salmon populations in a large (174 sq. mile) multibasin lake system were carried out during 1955, 1956 and 1957. Density and distribution of fingerling sockeye throughout the lake system are related to density and distribution of the spawning parent populations. Discrete populations associated with discrete basins point to a limited dispersal as a result of the multibasin nature of the lake system. In one example, higher population density appears to result in greater dispersal.

Using a Numerical Model of the Northeast Pacific Ocean to Study the Interannual Variability of the Fraser River Sockeye Salmon (Oncorhynchus nerka)

1991 ◽  
Vol 48 (4) ◽  
pp. 623-630 ◽  
Author(s):  
William W. Hsieh ◽  
Warren G. Lee ◽  
Lawrence A. Mysak
Keyword(s):  
Pacific Ocean ◽  
Interannual Variability ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Migration Route ◽  
Time Lags ◽  
Fraser River ◽  
Model Output ◽  
Northeast Pacific ◽  
Northeast Pacific Ocean

The hypothesis that numerical ocean circulation models could benefit fishery management was tested by first simulating the interannual variability of the northeast Pacific Ocean from 1955 to 1979 with the Bryan–Cox–Semtner ocean model (from the Geophysical Fluid Dynamics Laboratory, Princeton, NJ) and then relating the model output to the interannual variability found in the Fraser River sockeye salmon (Oncorhynchus nerka). Empirical orthogonal function (EOF) analysis was first used to condense the model output fields as well as the atmospheric forcing data. Next, the amplitude of the EOF's were regressed with the annual values of the sockeye variables (return migration route and timing, marine survival, and fork length) by stepwise multiple regression, with various time lags between the physical and the sockeye variables. The EOF modes associated with interannual variability (usually mode 2) were more often correlated with the sockeye variables than the other modes thought to contain mainly the seasonal cycle (mode 1) or else noise. The correlations between the physical variables and the sockeye variables were highest in the first and final few months of the sockeye marine life.

Variation in adult life history and morphology among Lake Washington sockeye salmon (Oncorhynchus nerka) populations in relation to habitat features and ancestral affinities

1997 ◽  
Vol 54 (1) ◽  
pp. 75-84 ◽  
Author(s):  
A P Hendry ◽  
T P Quinn
Keyword(s):  
Body Size ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
The Body ◽  
Age Composition ◽  
Body Depth ◽  
Native Populations ◽  
Lake Washington ◽  
Baker Lake ◽  
Different Origins

Body size, age composition, and male body depth were compared among five Lake Washington sockeye salmon (Oncorhynchus nerka) populations. Two of the populations (Bear and Cottage creeks) were indigenous to the watershed and three (Cedar River, Issaquah Creek, and Pleasure Point) were non-native (from Baker Lake, Washington). To isolate the relative contributions of habitat type and ancestral relatedness to phenotypic variation, we compared populations with (i) the same origin and similar habitats, (ii) different origins and different habitats, (iii) the same origin and different habitats, and (iv) different origins and similar habitats. Spawning salmon in the Cedar River were older and larger than those in the native populations, a result consistent with their origin (contemporary Baker Lake fish were also large and old) and with habitat variation (the Cedar River is much larger than Bear and Cottage creeks). Body size and age composition did not differ among the three non-native populations, but the body depth of males spawning on the lake beach (Pleasure Point) was greater than that of males in the Cedar River, suggesting adaptive divergence. Adaptive convergence may also have occurred because the population in Issaquah Creek (intermediate-sized creek) did not differ appreciably from those in Bear and Cottage creeks.

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
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