Trends in wild adult steelhead (Oncorhynchus mykiss) abundance for snowmelt-driven watersheds of British Columbia in relation to freshwater discharge

2000 ◽  
Vol 57 (2) ◽  
pp. 285-297 ◽  
Author(s):  
Barry D Smith
Keyword(s):  
British Columbia ◽  
Oncorhynchus Mykiss ◽  
Freshwater Discharge ◽  
Low Velocity ◽  
Factors Affecting ◽  
Ocean Climate ◽  
Juvenile Mortality ◽  
Annual Index ◽  
Time Series Analyses ◽  
Discharge Potential

Snowmelt-driven rivers of British Columbia support primarily summer-run steelhead (Oncorhynchus mykiss) that may spend up to 5 years as juveniles in freshwater. Time series analyses revealed significant negative correlations between an annual index of wild adult steelhead abundance (catch-per-angler-day, CpAD) for these rivers and summer freshwater discharge when these steelhead were juveniles. The strength of these relationships was related to latitude, with the more northerly rivers generating the strongest relationship between CpAD and freshwater discharge. Potential mechanisms by which interannual variation in freshwater discharge can modulate adult steelhead abundance include reduced juvenile mortality due to lower flow velocities during the warm summer months and to the creation of more juvenile habitat in low-velocity refuges. Alternatively, interannual variability in adult steelhead abundance is driven by variability in ocean climate of which freshwater discharge is an index. Interpretation of the data and analyses was encumbered in part by particular factors affecting CpAD as an index of abundance. However, the analyses support an interpretation that steelhead survival to adulthood might be influenced by freshwater conditions more so in northern snowmelt-driven rivers than in rainfall-driven rivers because steelhead from those rivers spend more years in freshwater as juveniles.

Trends in wild adult steelhead (Oncorhynchus mykiss) abundance in British Columbia as indexed by angler success

2000 ◽  
Vol 57 (2) ◽  
pp. 225-270 ◽  
Author(s):  
Barry D Smith ◽  
Bruce R Ward ◽  
David W Welch
Keyword(s):  
British Columbia ◽  
Time Series ◽  
Oncorhynchus Mykiss ◽  
Coastal Upwelling ◽  
Fiscal Year ◽  
Climate Indices ◽  
Factors Affecting ◽  
Gradual Introduction ◽  
Trends Over Time ◽  
Over Time

Intraregional similarities and interregional differences in wild steelhead (Oncorhynchus mykiss) abundance trends over time throughout British Columbia were identified using catch-per-angler-day (CpAD) as an index of abundance. This index was calculated using sport angler catch and effort data obtained by an ongoing mail-out questionnaire begun in the fiscal year 1967-1968. Despite high interannual variability in CpAD for individual rivers, its validity as an index of trends over time in wild steelhead abundance for geographic regions or watersheds is reinforced by similar trends yielded by both fishery-dependent and fishery-independent data. Time series methods generally could not build statistical support for the hypotheses that sudden regulation changes, or the gradual introduction over time of a catch and release philosophy, are generally important factors affecting trends over time in CpAD. This bolsters our confidence that the general patterns in mean CpAD over time within regions and watersheds reasonably index actual wild adult in-river steelhead abundance. We propose that the trends that we observe in wild steelhead CpAD are primarily driven by environmental influences. Some candidate environmental time series currently being considered and investigated are coastal upwelling, various ocean and atmospheric climate indices, freshwater discharge histories, and ultraviolet radiation.

Declining patterns of Pacific Northwest steelhead trout (Oncorhynchus mykiss) adult abundance and smolt survival in the ocean

2017 ◽  
Vol 74 (8) ◽  
pp. 1275-1290 ◽  
Author(s):  
Neala W. Kendall ◽  
Gary W. Marston ◽  
Matthew M. Klungle
Keyword(s):  
British Columbia ◽  
Time Series ◽  
Oncorhynchus Mykiss ◽  
Pacific Northwest ◽  
State Space Model ◽  
Puget Sound ◽  
Survival Rates ◽  
Steelhead Trout ◽  
Factors Affecting ◽  
Adult Abundance

Examination of population abundance and survival trends over space and time can guide management and conservation actions with information about the spatial and temporal scale of factors affecting them. Here, we analyzed steelhead trout (anadromous Oncorhynchus mykiss) adult abundance time series from 35 coastal British Columbia and Washington populations along with smolt-to-adult return (smolt survival) time series from 48 populations from Washington, Oregon, and the Keogh River in British Columbia. Over 80% of the populations have declined in abundance since 1980. A multivariate autoregressive state-space model revealed smolt survival four groupings: Washington and Oregon coast, lower Columbia River, Strait of Juan de Fuca, and Puget Sound – Keogh River populations. Declines in smolt survival rates were seen for three of the four groupings. Puget Sound and Keogh River populations have experienced low rates since the early 1990s. Correlations between population pairs’ time series and distance apart illustrated that smolt survival rates were more positively correlated for proximate populations, suggesting that important processes, including those related to ocean survival, occur early in the marine life of steelhead.

scholarly journals Ida Halpern: A Post-Colonial Portrait of a Canadian Pioneer Ethnomusicologist

2013 ◽  
Vol 16 (1) ◽  
pp. 41-59
Author(s):  
Kenneth Chen
Keyword(s):  
British Columbia ◽  
First Nations ◽  
Coast Salish ◽  
Factors Affecting ◽  
Post Colonial ◽  
Musical Development

The work of Ida Halpern (1910–87), one of Canada's first musicologists and a pioneer ethnomusicologist, has been largely ignored. This essay illuminates her most important contribution to the musical development of this country: the documentation of Native musics. Halpern devoted some four decades to recording and analyzing over five hundred songs of the Kwakwaka'wakw, the Nuuchahnulth, the Haida, the Nuxalk, and the Coast Salish First Nations of British Columbia—a truly remarkable achievement considering that a large part of her fieldwork was conducted during a period when it was illegal for Native cultures to be celebrated, much less preserved. The author discusses the strengths and weaknesses of her methodology as well as some factors affecting the reception of her work by academic peers and by the communities she worked with. While Halpern did not always thoroughly investigate context, she endeavoured to write heteroglossically and to invent a theory that accounted for the music of these songs.

Competition among juvenile Atlantic salmon (Salmo salar) and steelhead (Oncorhynchus mykiss): relevance to invasion potential in British Columbia

2001 ◽  
Vol 58 (1) ◽  
pp. 197-207 ◽  
Author(s):  
John P Volpe ◽  
Bradley R Anholt ◽  
Barry W Glickman
Keyword(s):  
British Columbia ◽  
Atlantic Salmon ◽  
Oncorhynchus Mykiss ◽  
Salmo Salar ◽  
Native Species ◽  
Competitive Ability ◽  
Atlantic Salmon Salmo Salar ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Status ◽  
Coastal British Columbia

Atlantic salmon (Salmo salar) are routinely captured in both freshwater and marine environments of coastal British Columbia (Canada). Recent evidence suggests that this species is now naturally reproducing in Vancouver Island rivers. Our objective was to quantify the performance of each species in intra- and inter-specific competition by assessing the competitive ability of Atlantic salmon sympatric with native niche equivalent steelhead – rainbow trout (Oncorhynchus mykiss). Significant behavioural differences, particularly with respect to agonism, were observed between species; however, the status of an individual as resident or challenger was the best predictor of performance. Resident fish always outperformed challengers, regardless of species. Thus, we suggest that Atlantic salmon may be capable of colonizing and persisting in coastal British Columbia river systems that are underutilized by native species, such as the steelhead.

Experimental Analysis of Microhabitat Selection by Juvenile Steelhead (Oncorhynchus mykiss) and Coho Salmon (O. kisutch) in a British Columbia Stream

1993 ◽  
Vol 50 (6) ◽  
pp. 1198-1207 ◽  
Author(s):  
Kurt D. Fausch
Keyword(s):  
British Columbia ◽  
Oncorhynchus Mykiss ◽  
Habitat Complexity ◽  
Field Experiments ◽  
Coho Salmon ◽  
Early Summer ◽  
Microhabitat Selection ◽  
Salmon River ◽  
Identical Construction ◽  
Stream Salmonids

Replicate experiments were conducted in the Salmon River, British Columbia, during early summer 1990 to test the relative importance of velocity refuge, visual isolation, and overhead cover to microhabitat selection by steelhead (Oncorhynchus mykiss) parr and age-0 coho salmon (O. kisutch). Four types of artificial Plexiglas structures, the first three of identical construction, had different portions painted to provide increasing habitat complexity: velocity refuge alone, velocity refuge with visual isolation, all three features combined, and overhead cover alone. Steelhead parr selected structures with overhead cover alone or all three features significantly more often than those without overhead cover. Steelhead also selected structures adjacent to the swiftest velocities available and closest to other natural overhead cover, which accounted for most differences in use of the same structure in different locations. In contrast, few age-0 coho salmon used any structures. Those that did selected the three types of structures with velocity refuge about equally, but significantly more often than those with overhead cover alone, regardless of their location. Field experiments such as this hold promise for elucidating mechanisms of habitat selection by stream salmonids.

Review: Receiver function studies in the southern Canadian Cordillera

1995 ◽  
Vol 32 (10) ◽  
pp. 1514-1519 ◽  
Author(s):  
John F. Cassidy
Keyword(s):  
British Columbia ◽  
Upper Mantle ◽  
Receiver Function ◽  
Vancouver Island ◽  
Moho Depth ◽  
Canadian Cordillera ◽  
Low Velocity ◽  
Strait Of Georgia ◽  
Low Velocity Zone ◽  
Velocity Zone

Receiver function analysis has proven to be a powerful, yet inexpensive tool for estimating the S-wave velocity structure of the crust and upper mantle beneath three-component seismograph stations in the southern Canadian Cordillera. Receiver function studies using a portable broadband seismograph array across southwestern British Columbia provided site-specific estimates for the location of the subducting Juan de Fuca plate. The oceanic crust was imaged at 47−53 km beneath central Vancouver Island, and 60–65 km beneath the Strait of Georgia. Further, these studies revealed a prominent low-velocity zone (VS = −1.0 km/s) that coincides with the E reflectors imaged ~5–10 km above the subducting plate on Lithoprobe reflection lines. The E low-velocity zone was shown to extend into the upper mantle beneath the Strait of Georgia and the British Columbia mainland, to depths of 50–60 km. Combining the receiver function and refraction models revealed a high Poisson's ratio (0.27–0.38) for this feature. The continental Moho was estimated at 36 km beneath the Strait of Georgia, and a crustal low-velocity zone associated with the Lithoprobe C reflectors beneath Vancouver Island was interpreted to extend eastward, near the base of the continental crust, to the British Columbia mainland. Analysis of data from the recently deployed Canadian National Seismograph Network demonstrates the variations in crustal thickness and complexity across the southern Canadian Cordillera, with the Moho depth varying from 35 km in the Coast Mountains, to 33 km near Penticton, to 50 km near the Rocky Mountain deformation front.

Sign in / Sign up

Export Citation Format

Share Document