Model of Salmon Age Structure and Its Use in Preseason Forecasting and Studies of Marine Survival

1982 ◽  
Vol 39 (11) ◽  
pp. 1444-1452 ◽  
Author(s):  
Randall M. Peterman
Keyword(s):  
Survival Rate ◽  
Density Dependence ◽  
Age Structure ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Spawning Areas ◽  
Forecasting Method ◽  
Salmon Stock ◽  
Marine Survival ◽  
Stock Abundance

A method is derived to determine whether ocean abundance of a salmon stock affects either the survival rate between particular ages or the proportion of the ocean population which migrates back to freshwater spawning areas. The approach, similar to Fredin's smolt indices method, uses data on brood-year contributions to adult returns in successive years. Survival rate and proportion maturing are found to be independent of stock abundance after age 3, except in Naknek River sockeye (Oncorhynchus nerka) data. In cases such as Babine Lake sockeye salmon, where nonlinearity has been identified previously in the relation between smolt abundance and total adult returns, this lack of density dependence in the older ages means that the mortality processes which cause that nonlinearity act early in smolt life. The relations between abundance of adult returns of age n in year t and returns of age n + 1 from the same brood class in year t + 1 are useful as preseason forecasting techniques. The method derived here, which uses logarithms of abundances, improves upon the existing forecasting method. Deviations from the relation between abundances of brood-year returns can in some cases be explained by smolt weight, which is shown to affect mean age at return.Key words: salmon age structure, marine survival, age-at-return, smolt weight, preseason forecasting

A Note on Variability of Marine Survival of Sockeye Salmon (Oncorhynchus nerka) and Effects of Flooding on Spawning Success

1987 ◽  
Vol 44 (10) ◽  
pp. 1791-1795 ◽  
Author(s):  
Richard E. Thorne ◽  
James J. Ames
Keyword(s):  
Sockeye Salmon ◽  
River Flow ◽  
Oncorhynchus Nerka ◽  
Major Effect ◽  
Flow Conditions ◽  
Annual Variability ◽  
Lake Washington ◽  
Salmon Stock ◽  
Marine Survival ◽  
Spawning Success

Most of the annual variability in sockeye salmon (Oncorhynchus nerka) survival has been assumed to be associated with freshwater stages, while marine survival has been assumed to be very consistent from year to year. Data from Lake Washington sockeye salmon stock, including hydroacoustic surveys of presmolt populations, indicate that marine survival may vary on the order of 4–20%. However, the data also show that river flow conditions during spawning and gravel incubation have a major effect on production for this stock.

Nonlinear Relation Between Smolts and Adults in Babine Lake Sockeye Salmon (Oncorhynchus nerka) and Implications for Other Salmon Populations

1982 ◽  
Vol 39 (6) ◽  
pp. 904-913 ◽  
Author(s):  
Randall M. Peterman
Keyword(s):  
Measurement Error ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Life Stage ◽  
Pink Salmon ◽  
Accurate Estimate ◽  
Large Variability ◽  
Marine Life ◽  
Mortality Effect ◽  
Marine Survival

Data on sampling variability in smolt abundance for Babine Lake sockeye salmon (Oncorhynchus nerka) are combined with a previous analysis to calculate a more accurate estimate of the degree of nonlinearity in the relation between smolts and adults. Results indicate significant within-stock nonlinear mortality, large variability in mortality which tends to obscure any smolt-to-adult relation, or both. Analysis of age structure data identifies the first 15 mo of marine life as the period when most of this nonlinear or relation-masking mortality occurs. I also calculate the amount of smolt measurement error below which other salmon stocks are classed as having nonlinear marine survival. A distinct separation between even and odd brood year marine survival of Babine Lake sockeye suggests interactions with pink salmon. Juvenile pink salmon (O. gorbuscha) abundances correlate positively with residuals in Babine Lake sockeye survival for the same seaward migration year. This suggests a depensatory mortality effect which occurs later in the marine life stage than the possible within-population compensatory effect. Depensation is plausible because the size of pink fry equals that of sockeye smolts by August in coastal waters, permitting mutual swamping of predators. The paper concludes with implications for further enhancement.Key words: density dependence, marine survival, measurement error, enhancement, depensation, nonlinear, variability

scholarly journals Simple dynamics underlie sockeye salmon (Oncorhynchus nerka) cycles

1998 ◽  
Vol 55 (10) ◽  
pp. 2355-2364 ◽  
Author(s):  
Ransom A Myers ◽  
Gordon Mertz ◽  
Jessica M Bridson ◽  
Michael J Bradford
Keyword(s):  
British Columbia ◽  
Density Dependence ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Stochastic Forcing ◽  
Stable Mode ◽  
Delayed Density Dependence ◽  
Cyclic Patterns ◽  
Ricker Model ◽  
Parameter Values

A variety of mechanisms have been proposed to explain the renowned British Columbia sockeye salmon (Oncorhynchus nerka) cycles, most of which invoke between-brood interactions (delayed density dependence) or depensatory harvest practices. We examine the dynamics of the Ricker model with realistic parameter values and suggest that the cycles could result from a stable mode excited by stochastic forcing. The previously proposed mechanisms are not required to generate cyclic patterns, although they could play a role in reinforcing cycles. Our results suggest that relaxing harvest rates will increase yields and decrease variability in sockeye abundances.

scholarly journals Physiology of individual late-run Fraser River sockeye salmon (Oncorhynchus nerka) sampled in the ocean correlates with fate during spawning migration

2006 ◽  
Vol 63 (7) ◽  
pp. 1469-1480 ◽  
Author(s):  
Steven J Cooke ◽  
Scott G Hinch ◽  
Glenn T Crossin ◽  
David A Patterson ◽  
Karl K English ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Acute Stress ◽  
Oncorhynchus Nerka ◽  
Spawning Migration ◽  
Fraser River ◽  
Stress Indicators ◽  
Spawning Areas ◽  
Plasma Estradiol ◽  
Somatic Energy ◽  
Estradiol Levels

Beginning in 1995, segments of the late-run sockeye salmon (Oncorhynchus nerka) stocks from the Fraser River, British Columbia, have initiated upriver spawning migration up to 6 weeks earlier than historical records; and those fish have experienced high rates of en route mortality. We examined the correlations between physiological and energetic status prior to river entry with subsequent migratory performance of individual salmon using telemetry and noninvasive biopsies for Adams–Thompson–Shuswap (Adams) and Weaver–Harrison (W–H) stocks. Salmon that failed to reach the river were characterized by a tendency to have elevated levels of chronic and acute stress indicators. For one stock of fish (i.e., Adams) that entered the river, those that died before reaching spawning grounds were individuals with low gross somatic energy. Furthermore, females tended to have elevated plasma estradiol levels. When contrasting fish with different behaviours and fates, fish that did not hold in the estuary and subsequently died tended to have less energy than fish that held and reached spawning areas. Females from the former group also had higher 11-ketotestosterone and estradiol levels relative to those from the later group. These data suggest that differences in physiological and energetic status may be associated with high en route mortality in late-run sockeye salmon.

AN INVESTIGATION OF THE LIFE HISTORY AND PROPAGATION OF THE SOCKEYE SALMON (ONCORHYNCHUS NERKA) AT CULTUS LAKE, BRITISH COLUMBIA: No. 4. THE LIFE HISTORY CYCLE OF THE 1925 YEAR CLASS WITH NATURAL PROPAGATION

1933 ◽  
Vol 8 (1) ◽  
pp. 345-355
Author(s):  
R. E. FOERSTER
Keyword(s):  
British Columbia ◽  
Life History ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Spawning Areas

Eggs spawned naturally by 3,883 females in 1925 were estimated as amounting to 17,470,000. Approximately 12,500 fry (0.07% of eggs) migrated to sea in 1926, 183,272 yearlings (1.05%) in 1927, and 1,722 two-year-olds (0.01%) in 1928, making 1.13% in all. Returning fish consisted of no three-year (32 group), 4,463 four-year (42 group), and 1,112 five-year fish (no 52 group, all being of the 53 group). None of the fish was reported returning to other spawning areas.

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.

Sockeye salmon (Oncorhynchus nerka) nursery lake fertilization: Review and summary of results

2004 ◽  
Vol 12 (3) ◽  
pp. 133-162 ◽  
Author(s):  
K D Hyatt ◽  
D J McQueen ◽  
K S Shortreed ◽  
D P Rankin
Keyword(s):  
Food Web ◽  
Green Algae ◽  
Sockeye Salmon ◽  
Inorganic Nitrogen ◽  
Oncorhynchus Nerka ◽  
Adult Survival ◽  
Bottom Up ◽  
Blue Green Algae ◽  
Marine Survival ◽  
Lake Fertilization

We reviewed 24 sockeye salmon (Oncorhynchus nerka) nursery lake experiments that involved whole-lake fertilization with appropriate treatment and control years. We found that: 21 of 21 studies showed that fertilization was associated with increased chlorophyll a concentrations, 16 of 16 showed increased zooplankton biomasses, 16 of 16 demonstrated increased average smolt weights, and 11 of 13 showed increased smolt biomasses. Studies involving assessments of egg-to-smolt survival were rare, but all (4 of 4) showed increased survival rates. Studies involving increased smolt-to-adult survival (i.e., marine survival) were even rarer, but all (3 of 3) showed that lake fertilization and increased smolt size were associated with increased marine survival. Several fertilization studies reported problems, and some offered solutions. For instance, when whole-lake fertilization stimulated the growth of blue-green algae, fertilizer with higher nitrogen to phosphorus ratios was used to control the problem. Conversely, when high nitrogen to phosphorus ratios were associated with blooms of ungrazable diatoms, notably Rhizosolenia eriensis, reduced nitrate concentrations were recommended. To date, solutions designed to constrain the growth of both blue-green algae and Rhizosolenia blooms remain elusive. Some studies showed that when both mysids (large invertebrate planktivores) and juvenile sockeye inhabit the same lake, sockeye suffer from a competitive disadvantage and mysids consume 80–90% of the available zooplanktonic food production. Similarly, a small number of studies demonstrated that competition from sticklebacks (Gasterosteus aculeatus) adversely affected sockeye growth rates, and although the problem remains unresolved, ongoing work in lakes containing kokanee (O. nerka), suggests that stocked cutthroat trout (Salmo clarki) may be capable of controlling stickleback densities through predation. Despite all of these difficulties, in almost all cases, when lakes were fertilized with various mixtures of inorganic nitrogen and phosphorus, pelagic food web bottom-up control was strong enough and predictable enough to ensure that sockeye smolt biomass increased. We conclude that sockeye nursery lake fertilization is a technique that can contribute usefully to both the enhancement and conservation of sockeye salmon populations. Key words: sockeye salmon, lake fertilization, bottom-up, aquatic food web.

Tributary Homing of Sockeye Salmon at Brooks and Karluk Lakes, Alaska

1964 ◽  
Vol 21 (3) ◽  
pp. 485-504 ◽  
Author(s):  
Wilbur L. Hartman ◽  
Robert F. Raleigh
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Small Lakes ◽  
Management Implications ◽  
Spawning Grounds ◽  
Spawning Area ◽  
Spawning Areas ◽  
Final Study ◽  
Color Combinations ◽  
Original Donor

The degree of preference of sockeye salmon (Oncorhynchus nerka) for spawning in specific tributaries to Brooks and Karluk Lakes, Alaska, was studied in 1960 and 1961. Adult sockeye salmon begin to congregate around stream mouths soon after entering these lakes. At Brooks Lake, groups of fish were seined from various stream mouths and marked with distinctive tag color combinations. One group of tagged fish from each seine haul was released back into the original donor congregation as a control, and one or more groups were transported and released into congregations around other tributary mouths. Strength of tributary preference was determined by comparing the number of fish from each group distributed on the various spawning grounds. Eighty-three per cent of the 958 fish tagged were recovered at weirs and on stream and lake surveys. Distribution to spawning areas of sockeye salmon in control and transported groups was virtually identical. The study at Brooks Lake was followed by a study at Karluk Lake to explore further the strength of tributary preference. Very few sockeye salmon experimentally prevented from entering their preferred tributary chose an alternative spawning area. Most continued to attempt to enter their blocked tributary until death. A final study at Karluk Lake confirmed the fact that sockeye salmon entering the lake were predisposed to spawn in a particular tributary and could not be conditioned to enter an alternative tributary. We conclude that sockeye salmon are indeed homing to particular tributaries in these small lakes. The biological and management implications of these findings are discussed.

Environmental and Parental Influences on Age at Maturity in Sockeye Salmon (Oncorhynchus nerka) from the Fraser River, British Columbia

1986 ◽  
Vol 43 (2) ◽  
pp. 269-274 ◽  
Author(s):  
Randall M. Peterman ◽  
Michael J. Bradford ◽  
Judith L. Anderson
Keyword(s):  
British Columbia ◽  
Age Structure ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Data Series ◽  
Fraser River ◽  
Age At Maturity ◽  
Long Term Effects ◽  
River Population ◽  
The Mean

Commercial fisheries possess the potential for applying strong selection on size or age at maturity in the populations they exploit. It is therefore important to know the extent to which these traits are inherited. We examined regressions of the mean age at maturity of cohorts of offspring on the mean ages of the female and male spawners which produced them for four populations of sockeye salmon (Oncorhynchus nerka) from the Fraser River, British Columbia. Unlike previous researchers, we found that neither genetic nor maternal effects are important, relative to environmental variables, in influencing year-to-year variation in age at maturity in these stocks. The differences between our findings and earlier ones are due to a longer data series and more complete population statistics than were available previously. We further analyzed the age structure of the Adams River population, which has a cyclic pattern of abundance. Fluctuating population density appeared to account for variation in age structure among cycle years in the Adams stock. We concluded that serious concerns about the long-term effects of size-selective fishing on mean age at maturity are probably not warranted for Fraser River sockeye.

Use of Biochemical Genetic Variants for Identification of Sockeye Salmon (Oncorhynchus nerka) Stocks in Cook Inlet, Alaska

1980 ◽  
Vol 37 (8) ◽  
pp. 1236-1247 ◽  
Author(s):  
W. S. Grant ◽  
G. B. Milner ◽  
P. Krasnowski ◽  
F. M. Utter
Keyword(s):  
Genetic Variation ◽  
Genetic Variants ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Maximum Likelihood Estimates ◽  
Starch Gel Electrophoresis ◽  
Cook Inlet ◽  
Allelic Frequencies ◽  
Spawning Areas ◽  
Biochemical Genetic

We used the geographic distributions of biochemical genetic variants in sockeye salmon (Oncorhynchus nerka) to describe features of its population structure and to identify stocks in commercial catches from the central fishing district of Cook Inlet, Alaska. Allelic frequencies for 6 polymorphic loci were determined for samples of 13 spawning areas using starch gel electrophoresis and were used as the basis of stock classification. The level of genetic variation, estimated by average heterozygosity, was 4.6%. Likelihood ratio tests for heterogeneity among allelic frequencies indicated a significant degree of heterogeneity among spawning areas within the Susitna and Kenai rivers, but not among the spawning areas within the Kasilof River. These tests also indicated that for the Kasilof River, where multi-year samples were taken, allelic frequencies were not significantly different for two consecutive years. Cluster analysis of genetic similarities between samples indicated that the samples from the Kasilof River were distinct from samples of the Kenai and Susitna rivers, but that Kenai and Susitna River samples were not distinct from one another. Maximum likelihood estimates of the stock composition of samples collected from the set- and drift-gillnet fisheries were made on a weekly basis during the commercial fishing season. These estimates indicated that Susitna River fish predominated in the 1976 run into Cook Inlet.Key words: sockeye salmon, Oncorhynchus nerka; stock identification, biochemical genetic variation, population genetics, Cook Inlet, electrophoresis

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