Density, climate, and the processes of prespawning mortality and egg retention in Pacific salmon (Oncorhynchus spp.)

2007 ◽  
Vol 64 (3) ◽  
pp. 574-582 ◽  
Author(s):  
T P Quinn ◽  
D M Eggers ◽  
J H Clark ◽  
H B Rich, Jr.
Keyword(s):  
Sockeye Salmon ◽  
Pacific Salmon ◽  
River System ◽  
Retention Rates ◽  
Bristol Bay ◽  
Egg Retention ◽  
Limited Sampling ◽  
Egg Deposition ◽  
Two Factors

In 2004 and 2005, exceptionally large runs of sockeye salmon (Oncorhynchus nerka) to the Alagnak River system in Bristol Bay, Alaska, coincided with weak runs to the nearby Kvichak River system. Restricted fishing to protect the Kvichak populations resulted in densities on the Alagnak River system's spawning grounds that were 11.5-fold (in 2004) and 9.0-fold (in 2005) above the long-term (1956–2003) average. Carcass sampling indicated that 23% (2004) and 44% (2005) of the potential egg deposition was lost to prespawning mortality or incomplete spawning in the Alagnak populations. Much lower levels of egg retentions were observed in spawning populations in the Kvichak River and Wood River systems, where the runs did not appreciably exceed the escapement goals, indicating that density-dependent spawning failure may have occurred. However, in 2005, significantly higher egg retention rates were observed in the Alagnak River system despite slightly lower densities than in 2004, indicating that environmental processes (probably low river levels and high temperatures) influenced prespawning mortality as well. More limited sampling in 2006 revealed only 3% egg retention in one of the Alagnak populations, but the combination of lower density and cooler conditions did not allow us to determine the relative contributions of these two factors to spawning failure.

Variance Components in the Estimation of Potential Egg Deposition of Sockeye Salmon Escapements

1969 ◽  
Vol 26 (3) ◽  
pp. 655-670 ◽  
Author(s):  
Ole A. Mathisen ◽  
Tor Gunnerød
Keyword(s):  
Variance Components ◽  
Variance Component ◽  
Sockeye Salmon ◽  
Bristol Bay ◽  
Egg Deposition ◽  
Average Fecundity

The magnitude of the variance components in the estimation of the potential egg deposition of sockeye salmon escapements to the Kvichak District, Bristol Bay, Alaska, was determined from data collected from 1957 to 1966. The greatest variance component was caused by estimation of the escapement followed by the variance due to estimation of the ratio of females in the escapement. Estimation of the average fecundity added the least variance.

A hierarchical model for salmon run reconstruction and application to the Bristol Bay sockeye salmon (Oncorhynchus nerka) fishery

2006 ◽  
Vol 63 (7) ◽  
pp. 1564-1577 ◽  
Author(s):  
Lucy Flynn ◽  
André E Punt ◽  
Ray Hilborn
Keyword(s):  
Hierarchical Structure ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Model Development ◽  
Bristol Bay ◽  
Process Error ◽  
The Hierarchical Structure ◽  
River Test ◽  
Run Timing

The goal of spreading the annual catch of a Pacific salmon (Oncorhynchus spp.) run proportionally across all segments of the migration is rendered difficult or impossible because of the interannual variability in both run size and run timing. This problem is particularly acute in the case of the fishery for sockeye salmon (Oncorhynchus nerka) in Bristol Bay, Alaska, for which traditional run reconstruction models are not applicable because of the extreme temporal compression of the run. We develop a run reconstruction model appropriate for sockeye salmon in Bristol Bay by accounting for the hierarchical structure of the problem and by including process error. Our results indicate that the hierarchical structure is, in fact, not necessary, whereas the process error parameters are needed to fit the data. We suggest further model development without the hierarchical structure, including incorporating in-river test fishing data. The results of our method can be used to address questions regarding environmental or intrinsic drivers of run timing and the possibility of artificial selection on run timing.

scholarly journals Implications of a warming eastern Bering Sea for Bristol Bay sockeye salmon

2011 ◽  
Vol 68 (6) ◽  
pp. 1138-1146 ◽  
Author(s):  
Edward V. Farley ◽  
Alexander Starovoytov ◽  
Svetlana Naydenko ◽  
Ron Heintz ◽  
Marc Trudel ◽  
...  
Keyword(s):  
Bering Sea ◽  
Sockeye Salmon ◽  
Large Scale ◽  
Pacific Salmon ◽  
Bristol Bay ◽  
Eastern Bering Sea ◽  
New Information ◽  
Energy Stores ◽  
Overwinter Mortality ◽  
Dependent Processes

Abstract Farley, E. V., Starovoytov, A., Naydenko, S., Heintz, R., Trudel, M., Guthrie, C., Eisner, L., Guyon, J. R. 2011. Implications of a warming eastern Bering Sea for Bristol Bay sockeye salmon. – ICES Journal of Marine Science, 68: 1138–1146. Overwinter survival of Pacific salmon (Oncorhynchus sp.) is believed to be a function of size and energetic status they gain during their first summer at sea. We test this notion for Bristol Bay sockeye salmon (O. nerka), utilizing data from large-scale fisheries and oceanographic surveys conducted during mid-August to September 2002–2008 and from February to March 2009. The new data presented in this paper demonstrate size-selective mortality for Bristol Bay sockeye salmon between autumn and their first winter at sea. Differences in the seasonal energetic signatures for lipid and protein suggest that these fish are not starving, but instead the larger fish caught during winter apparently are utilizing energy stores to minimize predation. Energetic status of juvenile sockeye salmon was also strongly related to marine survival indices and years with lower energetic status apparently are a function of density-dependent processes associated with high abundance of juvenile sockeye salmon. Based on new information regarding eastern Bering Sea ecosystem productivity under a climate-warming scenario, we hypothesize that sustained increases in spring and summer sea temperatures may negatively affect energetic status of juvenile sockeye salmon, potentially resulting in increased overwinter mortality.

scholarly journals Recent experience of surveying the spawning grounds of pacific salmons in the water bodies of Chukotka

2020 ◽  
Vol 200 (2) ◽  
pp. 270-291
Author(s):  
E. A. Shevlyakov ◽  
S. V. Shubkin
Keyword(s):  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
River System ◽  
Aerial Survey ◽  
Water Bodies ◽  
Recent Experience ◽  
Spawning Grounds ◽  
The Pacific ◽  
First Time

Aerial survey of the pacific salmon spawning grounds was conducted in the water bodies of Chukotka belonged to the Bering Sea basin (the Anadyr, Velikaya, Tumanskaya Rivers and Meinypilgyno lake-river system) in 2019, for the first time since 1992. Total flight time was 35 hours, approximate length of the transects was 3,800 km. Number of the spawners was estimated as 660.7 . 103 ind. for chum salmon, 112.2 . 103 ind. for sockeye salmon, and 3678.0 . 103 ind. for pink salmon, features of their distribution are described.

Uncertainties in population dynamics and outcomes of regulations in sockeye salmon (Oncorhynchus nerka) fisheries: implications for management

2008 ◽  
Vol 65 (7) ◽  
pp. 1459-1474 ◽  
Author(s):  
Carrie A. Holt ◽  
Randall M. Peterman
Keyword(s):  
Sockeye Salmon ◽  
Management Practices ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Simulation Models ◽  
Age At Maturity ◽  
Sources Of Uncertainty ◽  
Future Assessment ◽  
Long Term Trends

Fisheries managers usually have multiple options available but are often unclear on how to choose among them owing to uncertainties in biological and management components of fisheries systems. We evaluated the performance of current and possible future assessment and management practices for sockeye salmon ( Oncorhynchus nerka ) in British Columbia and Alaska by using a computer model that included major biological and management components and their associated uncertainties (interannual variability in recruitment, age-at-maturity, and sex ratio, as well as uncertainty in observations of spawner abundances, forecasts of recruitment, and outcomes from implementing management regulations). One option for management practices that we evaluated was designed to make the forecasting model more realistic by accounting for long-term trends in age-at-maturity. A second option was designed to reduce deviations between management targets and actual or “realized” harvest levels. We found that compared with practices that ignore those sources of uncertainty, the second option produced annual catches that were higher, on average, and less variable over time while maintaining recruitment above critical conservation levels. Contrary to our expectations, the first modification did not result in comparable benefits. Our results demonstrate the value of using simulation models to evaluate potential modifications to Pacific salmon management practices.

Recycling of Elements Transported Upstream by Runs of Pacific Salmon: II. δ15N and δ13C Evidence in the Kvichak River Watershed, Bristol Bay, Southwestern Alaska

1993 ◽  
Vol 50 (11) ◽  
pp. 2350-2365 ◽  
Author(s):  
Thomas C. Kline Jr. ◽  
John J. Goering ◽  
Ole A. Mathisen ◽  
Patrick H. Poe ◽  
Patrick L. Parker ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Coast Range ◽  
Bristol Bay ◽  
River Watershed ◽  
Dual Isotope ◽  
Salmon Juvenile ◽  
Dietary Component ◽  
Δ15n And Δ13c ◽  
Southwestern Alaska

Biota δ15N and δ13C values (deviations from recognized isotope standards) from lliamna Lake (a major anadromous sockeye salmon (Oncorhynchus nerka) nursery lake supporting peak-year runs > 10 million) and several other anadromous-salmon-free lakes in the Kvichak River watershed, Bristol Bay, southwestern Alaska, were compared to determine the significance of marine-derived nitrogen (MDN) delivered by returning adult salmon. Biota in lliamna Lake had higher δ15N compared with control lakes, verifying a mixing model correlating δ15N with MDN. Periphyton δ15N values reflected localized input from populations of spawning salmon. Juvenile sockeye MDN varied in response to escapement size, suggesting the importance of large escapements (> 10 million) for maintaining a predominantly MDN lacustrine N pool. Other resident fishes showed shifts in δ15N between years of high and low escapement. The dual-isotope approach, using δ15N and δ13C together, suggested that fish production is primarily dependent on limnetic primary and secondary production. The dual-isotope approach indicated that the coast range sculpin (Cottus aleuticus) was the only fish with an appreciable dietary component consisting of salmon eggs or emergent fry.

Use of the Kalman filter to reconstruct historical trends in productivity of Bristol Bay sockeye salmon (Oncorhynchus nerka)

2003 ◽  
Vol 60 (7) ◽  
pp. 809-824 ◽  
Author(s):  
Randall M Peterman ◽  
Brian J Pyper ◽  
Brice W MacGregor
Keyword(s):  
Kalman Filter ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Time Varying ◽  
Historical Trends ◽  
Bristol Bay ◽  
Fish Stocks ◽  
The Past ◽  
Better Than

Fisheries scientists and managers are concerned about potential long-term, persistent changes in productivity of fish stocks that might result from future climatic changes or other alterations in aquatic systems. However, because of large natural variability and measurement error in fisheries data, such changes are usually difficult to detect until long after they occur. Previous research using numerous Monte Carlo simulation trials showed that a Kalman filter performed better than standard estimation techniques in detecting such trends in a timely manner. Therefore, we used historical data along with a Kalman filter that included a time-varying Ricker a parameter to reconstruct changes in productivity (recruits per spawner at a given spawner abundance) of eight Bristol Bay, Alaska, sockeye salmon (Oncorhynchus nerka) stocks over the past 40 years. Productivity generally increased for most stocks but varied widely for others and dramatically decreased in another. Such large changes in productivity are important for management. They greatly affected optimal spawner abundances and optimal exploitation rates, suggesting that in the future, scientists should consider using models with time-varying productivity parameters.

Changes in size at maturity of Fraser River sockeye salmon (Oncorhynchus nerka) (1952–1993) and associations with temperature

1997 ◽  
Vol 54 (5) ◽  
pp. 1159-1165 ◽  
Author(s):  
S P Cox ◽  
S G Hinch
Keyword(s):  
Sockeye Salmon ◽  
Temporal Trend ◽  
Pacific Salmon ◽  
Sea Surface ◽  
Fraser River ◽  
Size At Maturity ◽  
Metabolic Demand ◽  
The Past ◽  
Using Data

Unlike other Canadian Pacific salmon (Oncorhynchus spp.), long-term declines in the size at maturity of Fraser River sockeye salmon (O. nerka) have not been reported in past studies. Using data specific for 10 Fraser River sockeye stocks, we demonstrate that size at maturity has generally declined over the past 42 yr for females in all stocks and for males from eight stocks. Independent of this temporal trend, we found that size at maturity of both sexes in all stocks was smaller in years when sea surface temperatures were relatively warm. Slower growth in warmer years may be caused directly by increased metabolic demand, or indirectly by oceanic changes that influence food acquisition. We speculate that fitness of Fraser River sockeye will be reduced in the future if sea surface temperature increases and salmon abundance remains near present levels.

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