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Author: Bryce Douglas Mecum
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 80
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Book Description
Pacific salmon (Oncorhynchus spp.) are an economically and culturally important genus of fishes endemic to the North Pacific. Their sustainable management depends on an understanding of the drivers of their abundance and migration dynamics. In many instances, statistical models are employed to predict abundance and run timing before harvest takes place to more effectively meet management objectives. In this thesis, I created a general-purpose predictive model of run timing that can be applied to many salmon populations. I then applied it to Yukon River Chinook salmon (O. tshawytscha) by generating pre-season predictions of inriver run timing, which I then compared with existing observations of run timing at two upriver locations. Prediction errors were low enough for the model to be useful to management. Models such as the one created in this study represent an objective tool that can be used to reduce subjectivity in fisheries management.
Author: Bryce Douglas Mecum
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 80
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Book Description
Pacific salmon (Oncorhynchus spp.) are an economically and culturally important genus of fishes endemic to the North Pacific. Their sustainable management depends on an understanding of the drivers of their abundance and migration dynamics. In many instances, statistical models are employed to predict abundance and run timing before harvest takes place to more effectively meet management objectives. In this thesis, I created a general-purpose predictive model of run timing that can be applied to many salmon populations. I then applied it to Yukon River Chinook salmon (O. tshawytscha) by generating pre-season predictions of inriver run timing, which I then compared with existing observations of run timing at two upriver locations. Prediction errors were low enough for the model to be useful to management. Models such as the one created in this study represent an objective tool that can be used to reduce subjectivity in fisheries management.
Author: John Heinrich Eiler
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 296
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[Cont.] Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors - an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season.
Author:
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 44
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Author: Bronwyn Lee MacDonald
Publisher:
ISBN:
Category :
Languages : en
Pages : 120
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In-season methods that produce accurate and timely forecasts of returning salmon abundances allow fisheries managers to alter fishing plans in order to meet conservation and harvest objectives. In-season methods are challenged by variability in catch statistics due to factors external to abundance, specifically, fluctuations in the migration timing of target and co-migrating stocks. I apply genetic stock identification (GSI) data to develop catch indices for the five Fraser Chinook management units, and use these indices to forecast returns for each management unit according to four in-season model forms. I evaluate models using three performance measures to determine forecasting errors. Results show that forecasts for Spring 52 and Summer 52 Chinook can be produced with reasonable accuracy early in the fishing season. Forecasts of Spring 42, Summer 41, and Fall Chinook are less accurate. Results indicate that this technique shows promise for providing accurate and timely forecasts for the five Fraser Chinook management units, particularly as additional years of data are GSI-analyzed.
Author: Toshihide Hamazaki
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 48
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This report describes a modeling framework to reconstruct the historical time series of drainagewide and stock-specific run and escapement of Pacific salmon Oncorhynchus spp. that return to a single large river system. The model combines historical data from various assessment projects that estimate mainstem passage, harvests, tributary escapements, and stock proportions under a single maximum-likelihood estimation framework. As a demonstration, the modeling framework was applied to reconstruct the historical (1981–2019) drainagewide run size and escapement of Yukon River Chinook salmon (O. tshawytscha) and each of the contributing stock components: Canada, Middle Yukon, and Lower Yukon. The model estimated that the average drainagewide (all stocks) run size was 301,000 (range: 109,000–491,000), escapement was 186,000 (88,000–305,000), and harvest rate was 35% (2–60%). The average Canada stock run size was 125,000 (39,000–214,000), escapement was 60,000 (14,000–126,000), and harvest rate was 48% (2–78%). The average Middle Yukon stock run size was 75,000 (22,000–139,000), escapement was 47,000 (14,000–126,000), and harvest rate was 35% (2–85%). The average Lower Yukon stock run was 101,000 (48,000–204,000), escapement was 78,000 (30,000–164,000), and harvest rate was 21% (1–51%). The next steps regarding the application of this model to Yukon River Chinook salmon should include a comprehensive data review, consideration of alternative model structures, and critical evaluation of model assumptions.
Author: Phillip Roy Mundy
Publisher:
ISBN:
Category : Fishes
Languages : en
Pages :
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Author:
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 107
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Author: Caitlin Burgess
Publisher:
ISBN:
Category : Salmon
Languages : en
Pages : 88
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Program RealTime provided tracking and forecasting of the 1999 inseason outmigration via the internet for stocks of wild PIT-tagged spring/summer chinook salmon. These stocks were ESUs from sixteen release sites above Lower Granite dam, including Bear Valley Creek, Big Creek, Cape Horn Creek, Catherine Creek, Elk Creek, Herd Creek, Imnaha River, Lake Creek, Loon Creek, Lostine River, Marsh Creek, Minam River, South Fork Salmon River, and Secesh River, Sulfur Creek and Valley Creek. Forecasts were also provided for a stock of hatchery-reared PIT-tagged summer-run sockeye salmon from Redfish Lake and for the runs-at-large of Snake River wild yearling chinook salmon, and steelhead trout. The 1999 RealTime project began making forecasts for a new stock of PIT-tagged wild fall subyearling chinook salmon, as a substitute for forecasts of the wild run-at-large, discontinued June 6. Forecasts for the run-at-large were discontinued when a large release of unmarked hatchery fish into the Snake River made identification of wild fish impossible. The 1999 Program RealTime performance was comparable to its performance in previous years with respect to the run-at-large of yearling chinook salmon (whole season MAD=3.7%), and the run of hatchery-reared Redfish Lake sockeye salmon (whole season MAD=6.7%). Season-wide performance of program RealTime predictions for wild Snake River yearling chinook salmon ESUs improved in 1999, with mean MADs from the first half of the outmigrations down from 15.1% in 1998 to 4.5% in 1999. RealTime performance was somewhat worse for the run-at-large of steelhead trout in 1999, compared to 1998, particularly during the last half of the outmigration when the MAD increased from 2.7% in 1998 to 6.1% in 1999. A pattern of over-predictions was observed in half of the yearling chinook salmon ESUs and the steelhead run-at-large during the month of May. Lower-than-average outflows were observed at Lower Granite dam during the first half of May, the only period of low flows in an year with otherwise higher-than-average-flows. The passage distribution of the stock new to the RealTime forecasting project, the PIT tagged stock of fall subyearling chinook salmon, was predicted with very good accuracy (whole season MAD=4.7%), particularly during the last half of the outmigration (MAD=3.6%). The RealTime project reverted to a pre-1998 method of adjusting PIT-tagged smolt counts at Lower Granite Dam because of its superior performance during the last half of the outmigration.
Author: Linda K. Brannian
Publisher:
ISBN:
Category : Chinook salmon fisheries
Languages : en
Pages : 40
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Report on estimates of total abundance (total run size), exploitation rate (maximum sustainable exploitation rate), and migration timing (lower and middle runs, Alaska and upper runs, Canadian origin) of chinook salmon (Oncorhynchus tschawytscha Walbaum) in the Yukon river, Alaska between 1982 and 1986.
Author: John Edward Clark
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 310
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