Missing the target: uncertainties in achieving management goals in fisheries on Fraser River, British Columbia, sockeye salmon (Oncorhynchus nerka)

2006 ◽  
Vol 63 (12) ◽  
pp. 2722-2733 ◽  
Author(s):  
Carrie A Holt ◽  
Randall M Peterman
Keyword(s):  
British Columbia ◽  
Fisheries Management ◽  
Return Migration ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Simulation Models ◽  
Mortality Rates ◽  
Fraser River ◽  
Management Options ◽  
Fishing Regulations

In sockeye salmon (Oncorhynchus nerka) fisheries, management targets are rarely achieved exactly, thereby creating uncertainties about outcomes from implementing fishing regulations. Although this type of uncertainty may be large, it is seldom incorporated into simulation models that evaluate management options. One objective of this study was to quantify the deviations that occur between realized and target mortality rates (i.e., the target fraction of adult recruits that die each year during return migration, mostly due to harvesting) in fisheries for sockeye salmon from the Fraser River, British Columbia. We found that for some sockeye stocks, realized mortality rates were higher than targets when recruitment was low (resulting in conservation concerns) and lower than targets when recruitment was high (resulting in foregone catch). Scientists and managers can at least partially account for effects of such deviations between realized and target mortality rates (outcome uncertainties) by choosing target harvest rules that reflect typical patterns in those deviations. We derived a method to permit modelers to incorporate those patterns into analyses of management options.

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.

scholarly journals Computer Simulations of the Influence of Ocean Currents on Fraser River Sockeye Salmon (Oncorhynchus nerka) Return Times

1994 ◽  
Vol 51 (2) ◽  
pp. 441-449 ◽  
Author(s):  
Keith A. Thomson ◽  
W. James Ingraham Jr. ◽  
Michael C. Healey ◽  
Paul H. LeBlond ◽  
Cornelius Groot ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Return Migration ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Vancouver Island ◽  
Ocean Currents ◽  
Fraser River ◽  
Return Times ◽  
Gyre Circulation ◽  
Model Fish

We hypothesized that the interannual variability of the northeast Pacific Ocean circulation affects the return times of Fraser River sockeye salmon (Oncorhynchus nerka). Homeward migrations were simulated for 1982 (with a relatively weak Alaska Gyre circulation) and 1983 (with a relatively strong circulation) in the context of three sequential return migration phases: a nondirected oceanic phase, a directed oceanic phase, and a directed coastal phase. Passive drifters were simulated to examine the influence of ocean currents during the nondirected oceanic phase: model fish south of 48°N were advected closer to Vancouver Island in 1983 compared with 1982; those north of 48°N were advected closer to Vancouver Island in 1982 than in 1983. Fish were simulated during the directed oceanic phase using a variety of behaviour scenarios: model fish starting south of 50°N had earlier return times in 1983 than in 1982; those starting north of 50°N had return times in 1983 that were generally the same as or later than in 1982. We inferred that ocean currents would modulate the environmental influences on return times during the directed coastal migration phase, by deflecting sockeye salmon into different oceanographic domains along the British Columbia coast.

Estimating Stock Composition of Migrating Juvenile Fraser River (British Columbia) Sockeye Salmon, Oncorhynchus nerka, Using Parasites as Natural Tags

1988 ◽  
Vol 45 (4) ◽  
pp. 586-591 ◽  
Author(s):  
R. E. Bailey ◽  
L. Margolis ◽  
C. Groot
Keyword(s):  
British Columbia ◽  
Maximum Likelihood ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Fraser River ◽  
Dominant Group ◽  
Strait Of Georgia ◽  
Natural Tags ◽  
Lake Washington ◽  
The Individual

Simulated mixtures of juvenile sockeye salmon (Oncorhynchus nerka) were constructed using parasite data to represent proportionally the major component stocks of Fraser River and Lake Washington sockeye migrating within the Strait of Georgia, British Columbia, in 1982–84. Samples of migrating juveniles were also collected from Bedwell Harbour, South Pender Island, British Columbia, each year and analyzed for parasites and stock composition. The compositions of simulated and sample mixtures were estimated using a maximum likelihood stock composition model. Simulated mixture compositions were accurately estimated for most stocks for all year-classes. When significant misassignment occurred between stocks, the stocks were analyzed as a complex using the allocate-sum procedure. Sample mixture estimates correctly identified the dominant stock for each year-class, although for 1984 the dominant group was determined as a complex of three stocks because the individual stocks were not distinguishable. The results indicate that it is feasible to use parasites as natural tags to estimate stock compositions of migrating juvenile sockeye salmon in the Strait of Georgia.

Cycles of abundance among Fraser River sockeye salmon (Oncorhynchus nerka)

1997 ◽  
Vol 54 (4) ◽  
pp. 950-968 ◽  
Author(s):  
W E Ricker
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Mortality Rates ◽  
Fraser River ◽  
Weak Line

In some but not all populations of sockeye salmon (Oncorhynchus nerka) that mature mainly at age 4, there has been a persistently ``dominant'' line, a ``subdominant'' line about 10-25% as large, and two weak lines having less than 1% as many fish as the dominant one. Suggested causes of this phenomenon that have been shown to be wrong or inadequate are the presence of a few sockeye of ages 3 and 5 in the spawning stocks and a somewhat larger rate of harvest of the nondominant lines. The only plausible type of explanation that has been suggested so far involves interaction between the dominant line and the others, and the only specific example involves a 4-year cycle of abundance of a predacious fish at Shuswap Lake, described by F.J. Ward and P.A. Larkin. Other types of interaction are possible, but have not been documented. The magnitudes of the instantaneous interaction mortality rates at Shuswap Lake are estimated as about 0.78 per generation for the subdominant line out of a 7.65 total, and 1.11 out of 7.94 for the weak line 3, line 4 being similar.

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.

Precocial maturation of male sockeye salmon in the Fraser River, British Columbia, and its relationship to growth and year-class strength

2000 ◽  
Vol 57 (11) ◽  
pp. 2248-2257 ◽  
Author(s):  
M C Healey ◽  
M A Henderson ◽  
Ingrid Burgetz
Keyword(s):  
British Columbia ◽  
Age Structure ◽  
Sockeye Salmon ◽  
Historical Data ◽  
Oncorhynchus Nerka ◽  
Fraser River ◽  
The West ◽  
Migration Distance ◽  
Male Brood ◽  
Class Strength

We analyzed historical data on the age structure and abundance of males in 22 populations of sockeye salmon (Oncorhynchus nerka) in the Fraser River, British Columbia, to determine geographical and temporal patterns of precocial maturation, its relationship with growth and maturation at other ages, and the value of precocial males as indicators of year-class strength. Most Fraser sockeye males spend two winters at sea before maturing at 3-5 years of age. Precocial males return to spawn at 2, 3, or 4 years of age (ages 0.1, 1.1, and 2.1) and comprised <1 to >33% of male brood year returns among populations. Precocity was lowest among populations that spawned far upstream and highest among populations spawning to the west of the main Fraser River and was not correlated with migration distance. Precocial maturation was related to growth during the second summer in the ocean to brood line and to brood line abundance. The combination of brood line, abundance, and size of precocial males accounted for more than 75% of the variation in total returns in four populations, suggesting that these variables might be used to predict abundance 1 year in advance.

Parvicapsula minibicornis infections in gill and kidney and the premature mortality of adult sockeye salmon (Oncorhynchus nerka) from Cultus Lake, British Columbia

2010 ◽  
Vol 67 (4) ◽  
pp. 673-683 ◽  
Author(s):  
Michael J. Bradford ◽  
Jan Lovy ◽  
David A. Patterson ◽  
David J. Speare ◽  
William R. Bennett ◽  
...  
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Premature Mortality ◽  
Fraser River ◽  
Myxosporean Parasite ◽  
Gill Disease ◽  
Gill Lamellae ◽  
Severity Of The Disease ◽  
Using Data

In recent years, large losses of migrating adult sockeye salmon ( Oncorhynchus nerka ) from the Fraser River, British Columbia, Canada, have resulted in reductions in catches and productivity. We investigated patterns of mortality and the occurrence of the myxosporean parasite Parvicapsula minibicornis in adult sockeye salmon from Cultus Lake, tributary to the Fraser River. Using data from a captive broodstock program, we found that early migrants to Cultus Lake had less severe P. minibicornis infections and were more likely to survive to maturity than those fish that arrived later after they had presumably held in the warmer Fraser River. We found P. minibicornis in kidneys and gills of spawners. In some fish, significant histopathology in the gills that included severe inflammation and hyperplasia of the gill lamellae was observed; the severity of the disease was correlated with the severity of P. minibicornis infections. Kidney and gill pathologies were more prevalent and more severe in fish that died before spawning compared with those that matured successfully. Gill disease associated with P. minibicornis infections had not been previously identified in Fraser River sockeye salmon, and its role in the loss of spawners needs further investigation.

Lipid Reserve Dynamics and Magnification of Persistent Organic Pollutants in Spawning Sockeye Salmon (Oncorhynchus nerka) from the Fraser River, British Columbia

2007 ◽  
Vol 41 (9) ◽  
pp. 3083-3089 ◽  
Author(s):  
Barry C. Kelly ◽  
Samantha L. Gray ◽  
Michael G. Ikonomou ◽  
J. Steve Macdonald ◽  
Stelvio M. Bandiera ◽  
...  
Keyword(s):  
British Columbia ◽  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Fraser River ◽  
Lipid Reserve

Institutional Learning and Spawning Channels for Sockeye Salmon (Oncorhynchus nerka)

1992 ◽  
Vol 49 (6) ◽  
pp. 1126-1136 ◽  
Author(s):  
Ray Hilborn
Keyword(s):  
British Columbia ◽  
Fisheries Management ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Decision Makers ◽  
The Other ◽  
Institutional Learning ◽  
1960S And 1970S ◽  
The 1960S ◽  
Design Construction

In the 1960s and 1970s, six artificial spawning channels for sockeye salmon (Oncorhynchus nerka) were constructed in British Columbia. I use the evaluation of these facilities and the response to the evaluation to test the hypothesis that fisheries management agencies can learn from experience. One of the facilities was almost immediately determined to be successful, but it took approximately 20 yr for the agency to evaluate the success of the other five. The evaluation was ambiguous for three of these. Only when facilities were overwhelmingly successful or total failures did clear answers emerge. The Canadian Department of Fisheries and Oceans (DFO) has experimented, evaluated, and learned about design, construction, and operation of spawning channels. DFO appears to be less successful at using the evaluation of adult production resulting from spawning channels. Learning appears to work best when goals are well defined, experiments can be conducted and evaluated rapidly, and there is a close organizational connection between decision makers, evaluators, and operators.

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