scholarly journals Effects of marine-derived nutrients on population dynamics of sockeye salmon (Oncorhynchus nerka)

2008 ◽  
Vol 65 (8) ◽  
pp. 1635-1648 ◽  
Author(s):  
Tadayasu Uchiyama ◽  
Bruce P. Finney ◽  
Milo D. Adkison
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Isotope Analysis ◽  
Juvenile Salmon ◽  
Juvenile Survival ◽  
Water Residence Time ◽  
Nitrogen Stable Isotope ◽  
Factors Affecting ◽  
Stock Recruitment ◽  
Marine Derived Nutrients

The effects of marine-derived nutrients (MDN) on the productivity of sockeye salmon ( Oncorhynchus nerka ) stocks in Alaska, USA, were examined through nitrogen stable isotope analysis of smolts and mathematical models of the sockeye stock–recruit relationship. Smolt δ15N was used to infer the degree to which smolts depend on MDN for their growth. We found that characteristics of sockeye nursery lakes and watersheds significantly affected the availability of MDN to juvenile sockeye. The magnitude of escapement and water residence time were the most important factors affecting the MDN availability to juvenile salmon. Analysis of stock–recruit models indicated that regional environmental fluctuations had a large effect on stock productivities. However, stock–recruitment data showed little evidence that increasing MDN input to nursery lakes increased stock productivities. Stock–recruitment data may be poorly suited to detection of the influence of MDN because of the multitude of factors that influence juvenile survival in the first several years of their life.

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.

Application of Bayesian decision analysis to management of a sockeye salmon (Oncorhynchus nerka) fishery

1998 ◽  
Vol 55 (1) ◽  
pp. 86-98 ◽  
Author(s):  
Christina A Robb ◽  
Randall M Peterman
Keyword(s):  
Decision Analysis ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Data Uncertainty ◽  
Optimal Decision ◽  
Management Decision ◽  
Bayesian Decision ◽  
Stock Recruitment ◽  
Salmon Stock ◽  
Parameter Values

We developed a decision-making framework for management of a sockeye salmon (Oncorhynchus nerka) fishery on the Nass River, British Columbia, that explicitly accounts for uncertainties in (i) the stock-recruitment relationship, (ii) annual recruitment, (iii) run timing, and (iv) catchability. The method used Monte Carlo simulation within a decision analysis framework and used Bayesian statistics to calculate probabilities for parameter values in the Shepherd stock-recruitment model. The decision dealt with when to open a fishery, upstream of all normal fishing areas, that is intended to harvest fish that are considered surplus to spawning requirements. The optimal decision rule for opening this fishery depended on (i) the relative importance of different management objectives and (ii) the range of shapes of the stock-recruitment relationship that were admitted as possible within the decision analysis. The management decision that was optimal if we assumed a dome-shaped stock-recruitment relationship was not optimal when we admitted the possibility of other shapes of the relationship. Therefore, given the variability in salmon stock-recruitment data, uncertainty in the shape of the stock-recruitment relationship should be routinely considered in analyses of management decisions.

Empirical and theoretical analyses of correction of time-series bias in stock-recruitment relationships of sockeye salmon (Oncorhynchus nerka)

1995 ◽  
Vol 52 (10) ◽  
pp. 2174-2189 ◽  
Author(s):  
Josh Korman ◽  
Randall M. Peterman ◽  
Carl J. Walters
Keyword(s):  
Time Series ◽  
Least Squares ◽  
Bias Correction ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Empirical Relationship ◽  
Estimation Method ◽  
Estimation Methods ◽  
Theoretic Approach ◽  
Stock Recruitment

Using data from 30 sockeye salmon (Oncorhynchus nerka) stocks and Monte Carlo simulations, we examined the importance of time-series bias on estimates of optimal harvest rate, optimal escapement, and sustainable yield. We compared the performance of the least-squares procedure for fitting a Ricker curve with an existing bias-correction method. Simulations showed that the effect of time-series bias is greatest for low-productivity stocks that exhibit a high degree of autocorrelation among residuals of the stock-recruitment relationship. A strong inverse empirical relationship between autocorrelation and stock productivity among the 30 stocks suggests that time-series bias is a more important concern for low-productivity northern stocks than for more productive southern stocks. The corrected method reduced bias in optimal escapement estimates under a limited set of conditions but at the price of increased variance in the estimates. For a constant escapement goal policy, using the bias correction thus resulted in sustainable yields slightly lower than or equal to expected values for 28 of the 30 stocks compared with yields obtained using the standard least-squares estimation method. We demonstrate the value of using a decision theoretic approach to evaluate the performance of estimation methods.

Factors Affecting Rainbow Trout (Salmo gairdneri) Predation on Migrant Fry of Sockeye Salmon (Oncorhynchus nerka)

1976 ◽  
Vol 33 (1) ◽  
pp. 19-24 ◽  
Author(s):  
R. M. Ginetz ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Development Stage ◽  
Salmo Gairdneri ◽  
Factors Affecting ◽  
Light Intensities ◽  
Salmon Fry ◽  
Lower Stream ◽  
Downstream Movement

Predation of rainbow trout (Salmo gairdneri) on migrant sockeye salmon (Oncorhynchus nerka) fry in experimental streams was higher on fry at an earlier development stage, in moonlight by contrast to cloudy night light intensities, at lesser turbidities, and at lower stream velocities. At dusk light intensities, from.05 to.30 ft-c, mortality from predation was inversely related to light intensity. The longer the period of exposure of fry to naturally declining light intensities prior to downstream movement, the lower was the loss to predators. Exposure of predators to high light intensities prior to the downstream movement of fry resulted in decreased fry mortality. Fry that had survived exposure to predators in an experimental stream 1 and 2 days previous were less vulnerable to predation than "naive" fry. Successive exposures further decreased the loss to predation. Fry enumerated at a counting fence suffered less predation than fry not enumerated. Experienced fry moved downstream more rapidly than naive fry.In laboratory aquaria, experienced fry formed compact schools prior to and in response to stimuli, while naive fry formed loose schools or did not school. Experienced fry were less active in responding to stimuli. Enumerated fry resembled experienced fry; nonenumerated fry resembled naive fry.Various techniques of enhancing sockeye salmon fry survival during downstream migration are suggested by these results.

Ecological relationship between freshwater sculpins (genus Cottus) and beach-spawning sockeye salmon (Oncorhynchus nerka) in Iliamna Lake, Alaska

1998 ◽  
Vol 55 (6) ◽  
pp. 1524-1533 ◽  
Author(s):  
Chris J Foote ◽  
Gayle S Brown
Keyword(s):  
Energy Flow ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Predatory Behavior ◽  
The State ◽  
Spawning Behavior ◽  
Cottus Cognatus ◽  
Ecological Relationship ◽  
Spawning Run ◽  
Marine Derived Nutrients

The interaction between two sculpin species, Cottus cognatus and Cottus aleuticus, and island beach spawning sockeye salmon (Oncorhynchus nerka) was examined in Iliamna Lake, Alaska. We conclude that sculpins actively move to specific spawning beaches and that the initiation of their movements precedes the start of spawning. Sculpin predation on sockeye eggs is positively dependent on sculpin size and on the state of the eggs (fresh versus water hardened), with the largest sculpins able to consume nearly 50 fresh eggs at a single feeding and 130 over a 7-day period. The number of sculpins in sockeye nests is greatest at the beginning of the spawning run, lowest in the middle, and high again at the end, with peak numbers of over 100 sculpins per nest (1 m2). We discuss the results in terms of energy flow of marine-derived nutrients into an oligotrophic system and in terms of the coevolution of sockeye spawning behavior and the predatory behavior of sculpins.

Cyclic Dominance and Optimal Escapement of Adams River Sockeye Salmon (Oncorhynchus nerka)

1990 ◽  
Vol 47 (4) ◽  
pp. 838-849 ◽  
Author(s):  
D. W. Welch ◽  
D. J. Noakes
Keyword(s):  
Sockeye Salmon ◽  
Net Present Value ◽  
Oncorhynchus Nerka ◽  
Total Yield ◽  
Confidence Regions ◽  
Parameter Estimates ◽  
Magnitude Comparison ◽  
Ricker Model ◽  
Stock Recruitment ◽  
Potential Benefits

We examined escapement policies for a stock-recruitment model with negative between-year interactions. Regardless of the degree of interaction present, the optimal policy is to always equalize escapement. Parameter estimates obtained for the Adams River sockeye salmon (Oncorhynchus nerka) indicate that between-year interactions may occur, but confidence regions include the null hypothesis of no interaction at all (the Ricker model). We conclude that the extreme amplitude of the current recruitment cycle in this stock frustrates statistical identification of interaction. It seems unlikely that between-year interactions will be measurable until the off year runs increase by at least two to three orders of magnitude. Comparison of total yields for the Adams River sockeye shows that an equal escapement policy could increase yields by at least 35% over that obtained by the current cyclic escapement pattern. This is equivalent to obtaining an additional $27 million in total yield per annum from the Adams River stock alone and, assuming a discount rate of 4%, translates into an increase in net present value of $675 million. If between-year interactions do not exist, the potential benefits of moving to an equal escapement policy are even larger, on the order of $3 to $4 billion.

scholarly journals Evaluation of factors affecting migration success of adult sockeye salmon (Oncorhynchus nerka) in the Yakima River, Washington, 2020

2021 ◽  
Author(s):  
Tobias J. Kock ◽  
Amy C. Hansen ◽  
Scott D. Evans ◽  
Richard Visser ◽  
Brian Saluskin ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Factors Affecting ◽  
Yakima River

Prevalence and patterns of scavenging by brown bears (Ursus arctos) on salmon (Oncorhynchus spp.) carcasses

2020 ◽  
pp. 9-17 ◽  
Author(s):  
A.E. Lincoln ◽  
A.J. Wirsing ◽  
T.P. Quinn
Keyword(s):  
Sockeye Salmon ◽  
Ursus Arctos ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Prey Consumption ◽  
Nutritional Intake ◽  
Total Consumption ◽  
Brown Bears ◽  
Factors Affecting ◽  
Scavenging Rates

Scavenging, an underappreciated mechanism of prey consumption for many predators, can contribute substantially to nutritional intake. Facultative scavengers such as brown bears (Ursus arctos Linnaeus, 1758) may both kill and scavenge Pacific salmon (genus Oncorhynchus Suckley, 1861), though the extent of scavenging and factors affecting this behavior are unclear. We tagged 899 sockeye salmon (Oncorhynchus nerka (Walbaum in Artedi, 1792)) carcasses and placed them on streambanks over 5 years at multiple sites in southwestern Alaska (USA) where brown bears annually prey on spawning sockeye salmon. Examination of carcasses revealed overall scavenging rates of 15% after 1 day and 54% after 3 days. Scavenging rate varied by site and year and increased throughout the salmon run. Contrary to predictions, scavenging was more frequent in senescent or bear-killed carcasses than ripe carcasses. Carcass consumption ranged from minimal to almost complete; body and brain tissues were most frequently consumed after 3 days (68% and 63% of carcasses, respectively). We also documented secondary scavenging (i.e., tissue consumption on two separate events) and delayed scavenging (i.e., scavenging observed after 3 days but not 1 day). Taken together, the results indicated that scavenging in these streams contributes significantly to total consumption of salmon by bears, with ramifications for other components of these salmon-dependent ecosystems.

Population dynamics and asynchrony at fine spatial scales: a case history of sockeye salmon (Oncorhynchus nerka) population structure in Alaska, USA

2012 ◽  
Vol 69 (2) ◽  
pp. 297-306 ◽  
Author(s):  
Thomas P. Quinn ◽  
Harry B. Rich ◽  
Dido Gosse ◽  
Nicolas Schtickzelle
Keyword(s):  
Population Structure ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Spatial Scales ◽  
Oncorhynchus Nerka ◽  
Abiotic Factors ◽  
Small Scale ◽  
Isolated Populations ◽  
Factors Affecting ◽  
Panmictic Population

Pacific salmon (Oncorhynchus spp.) exemplify the ways in which populations are structured by homing and the abiotic factors affecting their dynamics in discrete breeding and rearing habitats. What is the finest spatial scale of their population structure, and where do clusters of spatially proximate breeding groups lie along the continuum from isolated populations – metapopulation – patchy panmictic population? To investigate these questions, we monitored sockeye salmon, Oncorhynchus nerka, spawning in a complex of habitats ~1 km apart, joining to form a single stream flowing into Iliamna Lake, Alaska, USA. Annual surveys revealed levels of asynchrony in productivity that were comparable with values reported for sockeye salmon spawning in separate streams flowing into lakes elsewhere in Bristol Bay. A mark–recapture study revealed very little movement of spawning adults among habitats. The ponds occupied at highest density varied among years, and salmon consistently arrived and spawned later in one pond than the others. These results are consistent with the hypothesis that the salmon structured as a small-scale metapopulation rather than a single panmictic population.

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