scholarly journals Quantifying lost and inaccessible habitat for Pacific salmon in Canada’s Lower Fraser River

Ecosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Riley J. R. Finn ◽  
Lia Chalifour ◽  
Sarah E. Gergel ◽  
Scott G. Hinch ◽  
David C. Scott ◽  
...  
Keyword(s):  
Pacific Salmon ◽  
Fraser River

scholarly journals Are Lesser Snow Geese, Chen caerulescens caerulescens, Exceeding the Carrying Capacity of the Fraser River Delta's Brackish Marshes?

2006 ◽  
Vol 120 (2) ◽  
pp. 213 ◽  
Author(s):  
Mike W. Demarchi
Keyword(s):  
Carrying Capacity ◽  
Pacific Salmon ◽  
River Delta ◽  
Fraser River ◽  
Snow Goose ◽  
Chen Caerulescens ◽  
Snow Geese ◽  
Brackish Marshes ◽  
Fraser River Delta ◽  
Chen Caerulescens Caerulescens

Brackish marshes of the Fraser River delta provide important habitats for such high-profile animals as White Sturgeon (Acipenser transmontanus), Pacific Eulachon (Thaleichthys pacificus), Pacific salmon (Oncorhynchus spp.), Western Sandpiper (Calidris mauri), and Lesser Snow Goose (Chen caerulescens caerulescens), the latter comprising the “Fraser-Skagit” segment of the Wrangel Island (Russia) population. This study assessed whether the current numbers of Snow Geese are exceeding the carrying capacity of brackish marshes in the Fraser River delta. Simulation modelling predicts that those marshes are presently capable of supporting ~17,500 Snow Geese—a value that is greatly exceeded by the numbers of geese that have over-wintered there in recent years (~80,000 in 2004-2005). The Pacific Flyway Council’s target 3-y average population and segment sizes of 120,000 and 50,000 - 70,000, respectively, were set without considering the carrying capacity of natural wintering habitats, the potential impacts of too many geese on upland agriculture, or implications for hazards to civilian aircraft at Vancouver International Airport. The modelled results of the present study suggest that the Fraser River delta can sustain the current numbers of Snow Geese that stage or winter there only if those birds also forage in agricultural and refuge fields—a relatively recent phenomenon that likely bolstered the Snow Goose population. Over-use by Snow Geese can degrade the productivity and habitat quality of marshes. There is documented evidence that some key plant species (e.g., Scirpus americanus) of the brackish marshes of the Fraser River delta are well below their biomass potential (~15%), primarily because of grubbing by Snow Geese. Other species that depend on this brackish environment as well as human interests in the Fraser River delta may be adversely affected by an overabundance of Snow Geese. The future effectiveness of hunting as a primary means of population regulation is questioned.

Use of the stratified-Petersen estimator in fisheries management: estimating the number of pink salmon (Oncorhynchus gorbuscha) spawners in the Fraser River

1998 ◽  
Vol 55 (2) ◽  
pp. 281-296 ◽  
Author(s):  
Carl James Schwarz ◽  
Carolyn Gail Taylor
Keyword(s):  
Pacific Salmon ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Fraser River ◽  
Differential Migration ◽  
Mark Recapture ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
The Pacific ◽  
Recent Developments

The simple-Petersen estimator is a well-known mark-recapture method to estimate animal abundance. Two key assumptions are equal catchability in both samples and complete mixing of tagged and untagged animals. If these are violated, severe bias can occur. The stratified-Petersen estimator can be used to account for some of the heterogeneity in catchability or mixing. In this paper, we first review recent developments in the stratified-Petersen experiment for fisheries audiences and demonstrate some of the practical problems that can occur that have not been discussed in the theoretical literature. Second, we present a case study to estimate the gross escapement of Fraser River pink salmon (Oncorhynchus gorbuscha) in 1991. The motivation for this study is a discrepancy of over 5 million fish between the estimates as derived by the Pacific Salmon Commission (PSC) (7.5 million fish based on a hydroacoustic method) and the Department of Fisheries and Oceans (DFO), Canada (13.0 million fish based on a mark-recapture method). One hypothesis put forward was that the discrepancy may be due to the use of a pooled-Petersen estimator when there is differential migration over time. The stratified-Petersen model suggests that little of this discrepancy can be explained by differential migration.

Comment on “Gene flow increases temporal stability of Chinook salmon (Oncorhynchus tshawytscha) populations in the Upper Fraser River, British Columbia, Canada”Appears in Can. J. Fish. Aquat. Sci. 66: 167–176.

2010 ◽  
Vol 67 (1) ◽  
pp. 202-205 ◽  
Author(s):  
Terry D. Beacham ◽  
Ruth E. Withler
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
Temporal Stability ◽  
Time Span ◽  
Population Variation ◽  
Stock Identification ◽  
Fraser River ◽  
Mixed Stock ◽  
Conservation And Management

Temporally stable genetic structure among salmonid populations has been reported in many studies, although the time span evaluated in most studies is limited to 10 years or less. This result has important implications in conservation and management of Pacific salmon ( Oncorhynchus spp.) and ramifications for the construction and application of genetic databases for stock identification of fish sampled from mixed-stock fisheries. Walter et al. (2009. Can. J. Fish. Aquat. Sci. 66: 167–176) failed to consider recent studies providing evidence that their conclusion “the overall magnitude of temporal within-population variation exceeding that of among-population variation” for the populations under study may be invalid for Fraser River Chinook salmon ( Oncorhynchus tshawytscha ) populations. Their estimation of rates and patterns of migration among Chinook salmon populations also provided results that are difficult to reconcile with published information. Evaluation of the experimental designed employed by Walter et al. (2009) indicates that their sample sizes were too small to estimate reliably genetic variation among or within populations. Extrapolation of their conclusions relating temporal instability of population structure to other Chinook salmon populations or indeed other salmonid species is unwarranted.

Tissue residue concentrations of organohalogens and trace elements in adult Pacific salmon returning to the Fraser River, British Columbia, Canada

2010 ◽  
Vol 30 (2) ◽  
pp. 367-376 ◽  
Author(s):  
Barry C. Kelly ◽  
Michael G. Ikonomou ◽  
Nancy MacPherson ◽  
Tracy Sampson ◽  
David A. Patterson ◽  
...  
Keyword(s):  
British Columbia ◽  
Trace Elements ◽  
Pacific Salmon ◽  
Fraser River ◽  
Tissue Residue

scholarly journals Differential infestation of juvenile Pacific salmon by parasitic sea lice in British Columbia, Canada

2020 ◽  
Vol 77 (12) ◽  
pp. 1960-1968
Author(s):  
Cole B. Brookson ◽  
Martin Krkošek ◽  
Brian P.V. Hunt ◽  
Brett T. Johnson ◽  
Luke A. Rogers ◽  
...  
Keyword(s):  
British Columbia ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Host Specialization ◽  
Sea Lice ◽  
Oncorhynchus Keta ◽  
Lepeophtheirus Salmonis ◽  
Fraser River ◽  
Farmed Salmon ◽  
Louse Species

Fraser River Pacific salmon have declined in recent decades, possibly from parasitism by sea lice (Caligus clemensi and Lepeophtheirus salmonis). We describe the abundance of both louse species infesting co-migrating juvenile pink (Oncorhynchus gorbuscha), chum (Oncorhynchus keta), and sockeye (Oncorhynchus nerka) salmon over 5 years in the Discovery Islands and Johnstone Strait, British Columbia. The generalist louse, C. clemensi, was 5, 7, and 39 times more abundant than the salmonid specialist, L. salmonis, on pink, chum, and sockeye salmon, respectively. Caligus clemensi abundance was higher on pink salmon (0.45, 95% CI: 0.38–0.55) and sockeye (0.39, 95% CI: 0.33–0.47) than on chum salmon. Lepeophtheirus salmonis abundance was highest on pink salmon (0.09, 95% CI = 0.06–0.15). Caligus clemensi had higher abundances in Johnstone Strait than in the Discovery Islands. These results suggest differences in host specialization and transmission dynamics between louse species. Because both lice infest farmed salmon, but only C. clemensi infests Pacific herring (Clupea pallasii), conservation science and management regarding lice and Fraser River salmon should further consider C. clemensi and transmission from farmed salmon and wild herring.

Effects of natal water concentration and temperature on the behaviour of up-river migrating sockeye salmon

2018 ◽  
Vol 75 (12) ◽  
pp. 2375-2389 ◽  
Author(s):  
Collin T. Middleton ◽  
Scott G. Hinch ◽  
Eduardo G. Martins ◽  
Douglas C. Braun ◽  
David A. Patterson ◽  
...  
Keyword(s):  
British Columbia ◽  
Lake Water ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Metabolic Stress ◽  
Water Concentration ◽  
Regulated River ◽  
Reproductive Hormone ◽  
Fraser River ◽  
Stress Indices

Impoundments and diversions in freshwater corridors can alter the availability and concentration of natal water cues that migratory salmon rely on to guide homing during spawning migrations, although this has rarely been examined. By combining radiotelemetry and noninvasive biopsy, we provide the first detailed account of the effects of varying natal water concentrations, temperature, and individual physiology on the homing behaviour of wild adult Pacific salmon migrating through a regulated river. Most (89%) of the 346 sockeye salmon (Oncorhynchus nerka) from the two distinct populations tracked in this study in southwestern British Columbia (Canada) delayed their migration in the outlet of a powerhouse that discharges strong concentrations of natal lake water and subsequently wandered in the Fraser River before continuing upstream into the Seton River, where natal water cues can also vary. There were few associations between metabolic stress indices and reproductive hormone levels with this behaviour in either population; however, higher temperatures and elevated natal water concentrations in the Seton River were associated with shorter powerhouse delays and less wandering in late-run migrants.

The cumulative impacts of climate change on Fraser River sockeye salmon (Oncorhynchus nerka) and implications for management

2011 ◽  
Vol 68 (4) ◽  
pp. 718-737 ◽  
Author(s):  
Michael Healey
Keyword(s):  
Climate Change ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
The Arctic ◽  
Fraser River ◽  
Life Stages ◽  
Cumulative Impact ◽  
Marine Habitats ◽  
The Impact

Anadromous Pacific salmon ( Oncorhynchus spp.) are vulnerable to climate change in both freshwater and marine habitats. I use a qualitative model to assess the cumulative effects of climate change across life stages and generations of Fraser River sockeye salmon ( Oncorhynchus nerka ) and other salmon species. The effects of climate change most relevant to Fraser River sockeye include warming of freshwater and marine habitats, altered hydrology in spawning rivers, reduced productivity in nursery habitats, and changed distribution and phenology of predator and prey species. The weight of evidence indicates that these changes will negatively affect growth and survival of Fraser River sockeye at all life stages. Effects on one life stage will also carry forward to heighten adverse effects at subsequent life stages and across generations so that the cumulative impact is greater than the impact on individual stages. Salmon can adapt to climate change but probably not enough to sustain productivity. In the south, focus of policy and management on conserving and enhancing resilience is needed to retain some salmon production. At the same time, Arctic habitats are becoming accessible to salmon. Management in the Arctic should protect potentially productive habitats from development and facilitate their colonization by Pacific salmon.

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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