Recent declines in the recreational catch of coho salmon (Oncorhynchus kisutch) in the Strait of Georgia are related to climate

1999 ◽  
Vol 56 (3) ◽  
pp. 506-515 ◽  
Author(s):  
R J Beamish ◽  
G A McFarlane ◽  
R E Thomson
Keyword(s):  
Coho Salmon ◽  
Global Climate ◽  
Oncorhynchus Kisutch ◽  
Climate Indices ◽  
Strait Of Georgia ◽  
Dramatic Decline ◽  
Westerly Winds ◽  
Ocean Conditions ◽  
Climate Events ◽  
The Impact

Wild and hatchery-reared coho salmon (Oncorhynchus kisutch) from streams and rivers that flow into the Strait of Georgia are caught in the Strait of Georgia and off the west coast of Vancouver Island. The percentage of coho caught in either of these two areas varies from year to year. The variation is associated with the flow of freshwater from the Fraser River and became more extreme in the 1990's. In four of eight years in the 1990's and in the past three years, most coho have been caught outside the Strait of Georgia. The dramatic decline in the sport catch in the Strait is related to ocean conditions in the Strait. The change in ocean conditions is related to an increase in the number of days of zonal (westerly) winds in October, November, and December and to an increase in relative sea level height. The climate change about 1989 that affected the pattern of winter winds and the circulation in the Strait of Georgia was associated with changes in other global climate indices, demonstrating the impact that global climate events can have on the dynamics of regional salmon stocks.

Importance of Smolt Size and Early Ocean Growth to Interannual Variability in Marine Survival of Coho Salmon (Oncorhynchus kisutch)

1990 ◽  
Vol 47 (11) ◽  
pp. 2181-2194 ◽  
Author(s):  
L. Blair Holtby ◽  
Bruce C. Andersen ◽  
Ronald K. Kadowaki
Keyword(s):  
Interannual Variability ◽  
Coho Salmon ◽  
Age Groups ◽  
Oncorhynchus Kisutch ◽  
Northwest Coast ◽  
Size Distributions ◽  
Strongly Correlated ◽  
Large Size ◽  
Ocean Conditions ◽  
Marine Survival

The importance of smolt size and early ocean growth to the marine survival of coho salmon was examined over a 17-yr period at Carnation Creek, British Columbia. Comparisons of overall marine survival were made both between-years, using two smolt age-groups of different mean sizes, and within-years using observed smolt size distributions and smolt size distributions back-calculated from the scales of returning adults. Large size did not confer a consistent survival advantage but large smolts did survive better in years when marine survival was relatively poor. Marine survivals were strongly correlated with early ocean growth as estimated by the spacing of the first five ocean circuli on the scales of returning adults. Marine survival and early ocean growth were positively correlated with ocean conditions indicative of strong upwelling along the northwest coast of Vancouver Island. Neither smolt survival nor early ocean growth were correlated with regional coho smolt production. Our observations suggest that interannual variability in smolt survival was being driven by ocean conditions that determined smolt growth rates which subsequently affected the susceptibility of smolts to a size-selective predator.

Building an ecosystem model using mismatched and fragmented data: A probabilistic network of early marine survival for coho salmon Oncorhynchus kisutch in the Strait of Georgia

2013 ◽  
Vol 115 ◽  
pp. 41-52 ◽  
Author(s):  
H. Andres Araujo ◽  
Carrie Holt ◽  
Janelle M.R. Curtis ◽  
R.I. Perry ◽  
James R. Irvine ◽  
...  
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Ecosystem Model ◽  
Strait Of Georgia ◽  
Probabilistic Network ◽  
Marine Survival ◽  
Fragmented Data

Variation in Body Morphology Among British Columbia Populations of Coho Salmon, Oncorhynchus kisutch

1985 ◽  
Vol 42 (12) ◽  
pp. 2020-2028 ◽  
Author(s):  
Eric B. Taylor ◽  
J. D. McPhail
Keyword(s):  
British Columbia ◽  
Coho Salmon ◽  
Function Analysis ◽  
Oncorhynchus Kisutch ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Coastal Streams ◽  
Morphological Differences ◽  
Median Fins ◽  
Coastal British Columbia

Ten populations of juvenile coho salmon, Oncorhynchus kisutch, from streams tributary to the upper Fraser River, the lower Fraser River, and the Strait of Georgia region were morphologically compared. Juveniles from coastal streams (Fraser River below Hell's Gate and the Strait of Georgia) were more robust (deeper bodies and caudal peduncles, shorter heads, and larger median fins) than interior Juveniles. Discriminant function analysis indicated that juvenile coho could be identified as to river of origin with 71% accuracy. Juvenile coho from coastal streams were less successfully classified as to stream of origin; however, juveniles could be successfully identified as either coastal or interior with 93% accuracy. Juvenile coho from north coastal British Columbia, Alaska, and the upper Columbia system also fitted this coastal and interior grouping. This suggests that a coastwide coastal–interior dichotomy in juvenile body form exists. Three populations (one interior and two coastal) were studied in more detail. In these populations the coastal versus interior morphology was consistent over successive years, and was also displayed in individuals reared from eggs in the laboratory. Adult coho salmon also showed some of the coastal–interior morphological differences exhibited by juveniles. We concluded that the morphological differences between coastal and interior coho salmon are at least partially inherited.

Crystalline otoliths in teleosts: Comparisons between hatchery and wild coho salmon (Oncorhynchus kisutch) in the Strait of Georgia

2004 ◽  
Vol 14 (3) ◽  
pp. 361-369 ◽  
Author(s):  
R. M. Sweeting ◽  
R. J. Beamish ◽  
C. M. Neville
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Strait Of Georgia

scholarly journals Sources of predictability over the Mediterranean at seasonal time-scale: building up an empirical forecasting model

2021 ◽  
Author(s):  
Esteban Rodríguez-Guisado ◽  
Ernesto Rodríguez-Camino
Keyword(s):  
Time Series ◽  
Global Climate ◽  
Supplementary Information ◽  
Climate Indices ◽  
Least Squares Regression ◽  
Dynamical Models ◽  
Flexible Tool ◽  
Probabilistic Forecasts ◽  
The Mediterranean ◽  
The Impact

<p>Although most operational seasonal forecasting systems are based on dynamical models, empirical forecasting systems, built on statistical relationships between present and future at seasonal time horizons conditions of the climate system, provide a feasible and realistic alternative and a source of supplementary information. Here, a new empirical model based on partial least squares regression is presented. Originally designed as a flexible tool, the model can be run with many configurations including different predictands, resolutions, leads and aggregation times. To be able of producing forecast for any selected configuration, the model automatically selects predictors from an initial pool, containing global climate indices and specific predictors for the Mediterranean region unveiled in the frame of the MEDSCOPE project. Additionally, the model explores spatial fields, generating time series based on spatial averages of areas well correlated with the predictand. These time series are added to the initial pool of candidate predictors.  We present here results from a configuration producing probabilistic forecasts of seasonal (3 month averages) temperature and precipitation, their verification and comparison against a selection of state-of-the-art seasonal forecast systems based on dynamical models in a hindcast period (1994-2015). The model is able to produce spatially coherent anomaly patterns, and reach levels of skill comparable to those based on dynamical models. As predictors can be easily removed or incorporated, the model can provide information on the impact of a particular predictor on skill, so it can be used to help in the search and understanding of new sources of predictability. Evaluation of soil moisture impact on summer temperature predictability is shown as an example</p>

Spatial and temporal factors affecting survival in coho salmon (Oncorhynchus kisutch) in the Pacific Northwest

1998 ◽  
Vol 55 (9) ◽  
pp. 2067-2077 ◽  
Author(s):  
Claribel Coronado ◽  
Ray Hilborn
Keyword(s):  
British Columbia ◽  
Pacific Northwest ◽  
Coho Salmon ◽  
Survival Rates ◽  
Oncorhynchus Kisutch ◽  
Dominant Factor ◽  
Spatial And Temporal Patterns ◽  
Factors Affecting ◽  
The Pacific ◽  
Ocean Conditions

Survival rates for coho salmon (Oncorhynchus kisutch) were estimated for all coded wire tag release groups in the Pacific Northwest between 1971 and 1990. The spatial and temporal patterns show considerable geographic variation, with most regions south of northern British Columbia showing declining survival since 1983, while northern areas have shown increasing survival during that period. The number of years of operation explained very little of the variation in survival, and many hatcheries showed major increases in survival after several years of operation. Survival of marked wild fish generally showed the same trend as hatchery fish. We conclude that the dominant factor affecting coho salmon survival since the 1970s is ocean conditions and that there are major geographic differences in the pattern of ocean conditions. The decline in survival seen in British Columbia and south over the last decade suggests that a major reduction in exploitation rates is necessary to maintain the populations.

Spatial and interannual variability of juvenile coho salmon growth in the Strait of Georgia (2012-2015)

2020 ◽  
Vol 646 ◽  
pp. 145-160
Author(s):  
ML Journey ◽  
C Neville ◽  
G Young ◽  
M Trudel ◽  
BR Beckman
Keyword(s):  
Growth Factor ◽  
Regional Variation ◽  
Positive Relationship ◽  
Coho Salmon ◽  
Regional Growth ◽  
Oncorhynchus Kisutch ◽  
Fork Length ◽  
Small Scale ◽  
Short Term ◽  
Strait Of Georgia

We conducted a 4 yr (2012-2015) study of regional growth of juvenile coho salmon Oncorhynchus kisutch in the Strait of Georgia (British Columbia, Canada). Size (fork length) and growth (insulin-like growth factor-1 [IGF-1] concentration) varied both regionally and inter-annually. Additionally, we found a positive relationship between IGF-1 concentration and fork length that varied between years, with slopes and y-intercepts higher in 2012 and 2014, respectively, as compared to 2013 and 2015. An ordinal increase of IGF-1 concentration from the south to north in 2012 and 2014 was coupled with an increase in the prevalence of both juvenile herring and juveniles of other fish species in the diet. Across all years, there was a positive relationship between regional mean IGF-1 concentration and regional mean percent of juvenile herring in the diet. Our study demonstrates relatively small-scale spatial heterogeneity in juvenile coho salmon growth that in part, was attributed to regional variation in diet. These findings also demonstrate the utility of short-term growth measures (such as IGF-1) for assessing relatively small-scale spatial and temporal differences in growth.

A probabilistic analysis of decision-making about trip duration by Strait of Georgia sport anglers

1999 ◽  
Vol 56 (6) ◽  
pp. 960-972 ◽  
Author(s):  
Barry D Smith
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Access Point ◽  
Strait Of Georgia ◽  
Sport Fishery ◽  
Likelihood Model ◽  
Catch Rates ◽  
Autumn And Winter

Since 1984, an access-point creel survey of the Strait of Georgia, British Columbia, sport fishery has generated data on catch, effort, and attributes of effort from thousands of interviews of salmon anglers completing a daily boat-trip. I present a maximum-likelihood model for this daily bag limit (DBL) constrained fishery that estimates catch rate and variance for various angling fleets (as defined by boat-trip attributes such as the number of angling lines), estimates the probability that a boat-trip ends after a certain number of hours angling, and measures how angling success influences that probability. Most anglers targeting either chinook salmon (Oncorhynchus tshawytscha) or coho salmon (Oncorhynchus kisutch) became more likely to end a boat-trip in response to angling success, i.e., they were satiated by angling success before reaching a DBL. However, autumn and winter chinook salmon anglers tended to extend a boat-trip in response to angling success, i.e., they were motivated by angling success. Variability in angling success could not be attributed to variability in angler skill. Coho salmon catch rates increased by about 42% with each additional angling line per boat-trip up to three. The model can be used to judge the effectiveness of a DBL in reducing daily catch.

The impact of the global climate changes and the pollination

2016 ◽  
Author(s):  
Vera Lúcia Imperatriz Fonseca
Keyword(s):  
Climate Changes ◽  
Global Climate ◽  
Global Climate Changes ◽  
The Impact
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