Download or read book An Investigation Into the Factors Influencing Escapement Estimation for Chinook Salmon Oncorhynchus Tshawytscha on the Lower Shuswap River British Columbia microform written by Nicole Dorothy Trouton and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2004 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: The area-under-the-curve (AUC), method based on helicopter visual enumeration, is a commonly used technique to estimate escapement of chinook salmon (Oncorhynchus tshawytscha) for the Fraser River and its tributaries. Two key factors associated with this method are survey life and observer efficiency. The survey life currently assumed by Fisheries and Oceans Canada (DFO) for Thompson Basin streams is seven days and for most counting flights the assumed observer efficiency is 100%. Telemetry and tower observations were used to estimate annual (2000-2002) survey lives for male (telemetry) and female (telemetry and tower observation) chinook salmon in the Lower Shuswap River. Mark-recapture based survey lives were directly estimated by dividing the mark-recapture escapement estimate by the AUC estimate of total spawner days. Observer efficiency was estimated by comparing observer counts from helicopters to counts from photographs. Various combinations of total fish counts, observer efficiencies, and survey lives were used in AUC escapement estimates, and compared to mark-recapture and peak count estimates. Survey lives varied annually. Many of the estimated mean survey lives were significantly less than seven days; mark-recapture based survey lives were generally less than those estimated from telemetry and observations from towers; and mean survey lives for males were higher than for females. The mean observer efficiency of helicopter enumeration was 97% (95% CI is * 6%), this is not significantly different than the 100% assumed by DFO.
Download or read book Factors Influencing the Return of Fall Chinook Salmon Oncorhynchus Tshawytscha to Spring Creek Hatchery written by Charles O. Junge and published by . This book was released on 1963 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Comparison of Escapement Estimate Methods Plus Escapement recruitment Relationships for Chinook Salmon and Coho Salmon in a Coastal Stream written by Stephen A. Gough and published by . This book was released on 2010 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Changes in Size and Age at Maturity of Columbia River Upriver Bright Fall Chinook Salmon Oncorhynchus Tshawytscha written by Roy E. Beaty and published by . This book was released on 1992 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: The average size and age of chinook salmon (Oncorhynchus tshawytscha) caught in commercial fisheries along the Pacific Coast of North America have decreased substantially in this century. These declines might be caused in part by changes in size and age at maturity within the stocks contributing to those fisheries. Upriver Brights (Brights), a stock of fall chinook salmon in the Columbia River, are one of those stocks. The purposes of this study were to (1) determine if average size and age at maturity of Brights have declined, (2) gain a better understanding of the factors that may contribute to such declines, and (3) describe potential consequences of these changes. Data from in-river fisheries suggest that the average weight of mature Brights returning to the Columbia River has decreased approximately 2.7 kg since the 1910s, an average rate of about 0.1 lb·yr−1 (45 g·yr−1). Most of the potential biases in these data tend to make this estimate conservative. Insufficient data were available to describe changes in average age at maturity. There are many potential causes for the decline in average size of mature Brights, including factors that affect very early life stages. Other researchers have determined that size at maturity appears to be highly influenced by inheritance, gender, and growth rate. I describe how maternal size can influence -- through time of spawning, choice of spawning site, and egg size -- the viability of the young, which carry the dam's genes for size. The size-related ability to produce viable offspring may have been changed by modifications in the environment. Very little is known about how changes in the natural environment for spawning, incubation, and rearing may have contributed to a decline in average size at maturity. Artificial propagation and rearing, such as at Priest Rapids Hatchery, seems to produce adult Brights that are smaller, younger, and more likely to be male than their natural counterparts. The net result is that the average hatchery fish may have only about 0.80 of the reproductive potential of the average natural fish. Changes in growth conditions in the ocean probably did not contribute to the change in size, although the ocean fisheries of Southeast Alaska and British Columbia appear to select, in the genetic sense, against large size and old age in Brights. Since 1978, in-river commercial fisheries have caught larger Brights and a higher proportion of females than are found in the escapement of the Priest Rapids Hatchery component of the stock, but the fisheries impact the two sexes differently by taking the larger males and the smaller females. The effect on the natural component may differ because of their apparently larger average size. I found no evidence that larger fish or more females were caught when 8-in. minimum restrictions were in effect on gillnet mesh size relative to periods when mesh size was not restricted. Impounding the mainstem during the last 50+ yr may have removed obstacles to migration (e.g., Celilo Falls) that selected for large size in Brights, but that hypothesis could not be tested. The perserverance of larger and older phenotypes in the Bright stock suggests that countervailing selection -- perhaps during spawning, incubation, and/or early rearing -- may have resisted the effects of a century of size- and age-selective fisheries. That resistance, however, may reduce the productivity of the stock. Declines in average size and age at maturity can have undesireable consequences. Lower average size means less biomass landed and lower commercial value. Lower average fecundity and a diminished ability to reproduce in some environments are also expected. Loss of size and age classes may reduce the ability of the stock to adapt to environmental variations. These results are relevant to several management practices. A holistic approach to fishery management issues is necessary to avoid erroneous conclusions based on narrow perspectives. Measuring reproductive potential of the catch and escapement would be superior to the conventional practice of simply counting numbers of fish. Many aspects of artificial propagation can be improved, including broodstock aquisition, mating regimes, and rearing practices. Stock abundance is a major factor in determining the effect of many management practices on the stock. In general, fisheries managers must be mindful that they manage very complex natural systems.
Download or read book Death of a Salmon written by Ian Geoffrey Brosnan and published by . This book was released on 2014 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: From 2008 to 2011, migrating acoustic-tagged juvenile yearling Chinook salmon smolts (Oncorhynchus tshawytscha) were detected on receivers deployed across the Columbia River and continental shelf at Cascade Head (Oregon), Willapa Bay (Washington), and Vancouver Island (British Columbia). The telemetry data were used to estimate survival and record migration parameters. These were evaluated against oceanographic and freshwater hydrologic variables in statistical and individual-based models. Plume survival was found to be variable, but daily survival rates were more constant and survival was effectively modeled as exponential decay. Correlates of early marine survival that do not have direct effects may act on plume survival by controlling the period of exposure to plume predation. In 2011, half of smolts released were exposed to total dissolved gas levels (TDG) above 120%, the water quality limit for TDG below Columbia River dams. This exposure appears to have negatively affected daily survival rates in the lower river and plume, and has important implications for a proposal to increase the TDG limit to 125% to support spring fish passage. Finally, consistent with the critical size, critical period hypothesis of salmon production, it appears that smolts select habitat to maximize their growth as they migrate north through the plume, rather than selectively using local currents to speed their passage. These findings shed new light on perennial questions in salmon early marine ecology. They lay the groundwork for future research aimed at understanding the effects of changing oceanography and freshwater hydrology on salmon migration and survival.
Download or read book Gulkana River Chinook Salmon Escapement Estimation 2022 2026 written by Tracy R. Hansen and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Objectives of this study are to estimate the spawning escapement and run timing of Chinook salmon Oncorhynchus tshawytscha in an index area of the Gulkana River using counting tower methodology. In addition, sockeye salmon O. nerka escapement at the tower site will be estimated during the period of tower operation. The number of Chinook salmon and sockeye salmon passing the tower site will be estimated by visually counting fish as they pass 2 counting towers located approximately 2.5 km upstream of the confluence of the West Fork. Ten-minute visual counts will be conducted for each river channel every hour, 24 hours per day, 7 days per week. The abundance estimates will be stratified by day. Because counts are planned for all hours, daily estimates of abundance will be a single-stage direct expansion from the 10 min counting periods. The count schedule will start prior to the beginning of the Chinook salmon run, approximately 3 June, and continue until after 10 August when the run is complete. Tower operations may be extended to a later date to enumerate more of the sockeye salmon run if funding is provided by Prince William Sound Aquaculture Corporation.
Download or read book Evaluation of Models and the Factors Affecting the Migration and Growth of Naturally produced Subyearling Fall Chinook Salmon Oncorhynchus Tshawytscha in the Lower Snake River written by John M. Plumb and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 2 of this dissertation focuses on evaluating the performance of the Wisconsin bioenergetics model for subyearling Chinook salmon by using data obtained from four different laboratory studies. Taking this "evaluation step" with respect to the bioenergetics model seemed prudent given that (1) bioenergetics models are a common means (with strong theoretical support) to evaluate fish growth and consumption from field observations, yet (2) systematic error in consumption and growth estimates have been shown to be widespread in the literature, particularly when model parameters are applied to other species, life stages, or locally-adapted populations from which the models were originally calibrated. Evaluating the bioenergetics model prior to its application was important because high growth rates for subyearling Snake River fall Chinook salmon have been reported in both a laboratory (Geist et al. 2010) and in the wild (Connor and Burge 2003). This research compares inland Snake River subyearlings to subyearlings from British Columbia, Canada (Brett et al. 1982), and so also evaluates the application of the Wisconsin bioenergetics model to different populations of subyearling fall Chinook salmon (Chapter 2).
Download or read book Study of Factors Influencing the Return of Fall Chinook Salmon Oncorhynchus Tshawytscha to Spring Creek Hatchery written by Charles O. Junge and published by . This book was released on 1960 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chilkat River Chinook Salmon Escapement Studies in 2022 written by Brian W. Elliott and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chilkat River large (age-1.3 and older) Chinook salmon Oncorhynchus tshawytscha inriver abundance and age and sex composition will be estimated using a 2-event mark–recapture experiment in 2022. Event 1 marking is conducted in the lower Chilkat River, and event 2 recapture is conducted in principal spawning areas within the Chilkat River drainage. Data produced from this project includes estimated spawning abundance and age, sex and length compositions of the large Chinook salmon run, and when possible, estimated spawning abundance and sex and length composition of the age-1.2 Chinook salmon run in the Chilkat River drainage. The Chilkat River stock of Chinook salmon is a Pacific Salmon Commission Chinook Technical Committee exploitation rate and escapement indicator stock, and contributes toward the coastwide Chinook model used by the Pacific Salmon Commission to monitor coastwide abundance. Mark–recapture experiments of adult Chinook salmon inriver abundance have been conducted in the Chilkat River drainage since 1991 and resulting escapement estimates have had an average coefficient of variation of 16%, which contributes toward precise stock assessment production estimates for the Chilkat River Chinook stock. As part of ongoing Chilkat River Chinook salmon coded wire tag studies, all Chinook salmon encountered in the mark–recapture experiment of adult Chinook salmon inriver abundance will be examined for missing adipose fins, an indication that fish may be tagged with a coded wire tag, information that leads to estimates of juvenile production and marine harvest. These data when used in conjunction with inriver abundance allows full production estimates for the Chilkat stock.
Download or read book Expanding Nushagak River Chinook Salmon Escapement Indices to Inriver Abundance Estimates Using Acoustic Tags 2011 2014 written by Suzanne L. Maxwell and published by . This book was released on 2020 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: An acoustic tag study was conducted at the Nushagak River from 2011 to 2014 to determine which portions of the river Chinook salmon Oncorhynchus tshawytscha migrate through as they pass the location of a project that uses sonar to estimate salmon passage. The tagging study was done in conjunction with the sonar project, a project that uses DIDSON (dual-frequency identification sonar) and drift gillnetting techniques to estimate sockeye O. nerka, Chinook, and chum O. keta salmon passage. Chinook salmon estimates from the sonar project are an important tool for fishery managers even though an unknown proportion migrate beyond the sonar’s limited sampling range, ~30% of the river’s width. Acoustic tags were inserted into Chinook salmon captured in drift gillnets 13 km downriver from the sonar site. An acoustic receiver array deployed at the sonar site detected 94.6% of the tagged fish, and 81.9% produced usable tracks. The percentage of tagged fish that passed through 1 or both sonar beams using length-stratified groupings was 65% in 2011, 54% in 2012, 64% in 2013, and 47% in 2014, averaging 57%. Although tagged fish were observed across the entire array, dominant travel lanes emerged that differed among study years. Expanding the sonar estimates of Chinook salmon using length-stratified proportions increased the estimates by 59,251–146,409 fish per year from sonar estimates that ranged from 70,482 to 174,085 fish per year. Our recommendations are to continue the acoustic tag study for 3 years to confirm the stability of the expansion factors and improve sonar estimates by adding a midriver sampling zone or expanding past and future estimates using expansion factors from this study.
Download or read book Estimation of the Escapement of Chinook Salmon in the Unuk River in 2005 written by Jan L. Weller and published by . This book was released on 2006 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report estimates the abundance of medium and large chinook salmon, Oncorhynchus tshawytscha, that returned to spawn in the Unuk River in 2005, using a two-event mark-recapture experiment.
Download or read book Historical Estimates of Run and Escapement for Chinook Salmon Returning to the Nushagak River 1968 2020 written by Jordan Head and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A maximum likelihood model was developed to estimate the 1968–2020 drainagewide run size and escapement of Nushagak River Chinook salmon (Oncorhynchus tshawytscha). The model simultaneously combined information by direct observations of escapement at 8 locations (1 tower and 7 aerial surveys); harvest of fish from commercial, subsistence, and sport fisheries; inriver abundance indices from the Nushagak River sonar project; and inriver abundance estimates from acoustic tag and mark–recapture studies. Results showed that reconstructed total run size ranged from 74,000 to 629,000 Chinook salmon with an average run size of 282,000 fish, and escapement ranged from 49,000 to 476,000 fish with an average of 210,000 fish. The model estimated total run and escapement appeared to be reasonable and tracked well with previous estimates. The major deficiency of this model is the absence of overlapping, long-term escapement and run monitoring data.
Download or read book Estimated Abundance of Chinook Salmon Returning to the Nass River BC 1997 written by Michael R. Link and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since 1994, a mark-recapture experiment has been used to estimate the annual system-wide chinook salmon escapement to the Nass River, British Columbia. This report describes and presents results from the 1997 experiment, which was designed to test some basic assumptions that heretofore had not been rigorously examined. The objectives of the study were to: determine if the fishwheels used to capture the salmon were size- and/or stock-selective, and if so, examine the implications of ignoring fishwheel selectivity when estimating escapement; estimate the abundance of chinook spawning in the Nass watershed in 1997; and recommend a cost-efficient, long-term study design to accurately estimate the annual, system-wide escapement of chinook to the Nass River. Results are presented and discussed with regard to catches, catch per unit effort, tagging, tag recovery and loss, spawning ground surveys, size selectivity, recoveries among tributaries of the Nass River, and factors affecting escapement estimates. Recommendations are made for the 1998 study.
Download or read book Chinook Salmon Escapement and Run Timing in the Gulkana River 2016 2018 written by Corey J. Schwanke and published by . This book was released on 2019 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Counting tower techniques were used to estimate Chinook salmon Oncorhynchus tshawytscha escapement in the Gulkana River during 2016, 2017, and 2018. The counting tower was located in the mainstem Gulkana River about 3.25 rkm upstream of the West Fork Gulkana River confluence. The estimated escapement of Chinook salmon was 1,122 (SE = 166; 95% CI = 796-1,447) in 2016, 3,336 (SE = 309; 95% CI = 2,730-3,942) in 2017, and 5,174 (SE = 344; 95% CI = 4,499-5,848) in 2018. These numbers do not represent total inriver escapement, just passage above the counting tower site. The 2016 estimated escapement of Chinook salmon was the lowest since the inception of the project in 2002, whereas the 2018 estimated escapement was the 2nd highest on record and had the latest run timing. The dates of 25th, 50th, and 75th percentile passage of Chinook salmon have been getting later since the project's inception in 2002. The estimated escapement of sockeye salmon O. nerka during the counting tower's operational period was 26,010 (SE = 1,157; 95% CI = 23,743-28,277) in 2016, 20,492 (SE = 927; 95% CI = 18,675-22,309) in 2017, and 12,436 (SE = 540; 95% CI = 11,377-13,494) in 2018. The partial sockeye salmon escapement estimate in 2018 was the 2nd lowest since the inception of this project in 2002.
Download or read book Estimation of the Escapement of Chinook Salmon in the Unuk River in 2004 written by Jan L. Weller and published by . This book was released on 2006 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report estimates the abundance of medium and large chinook salmon Oncorhynchus tshawytscha that returned to spawn in the Unuk River in 2004, using a two-event mark-recapture experiment.
Download or read book Estimation of the Escapement of Chinook Salmon in the Unuk River in 2006 written by Jan L. Weller and published by . This book was released on 2009 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report estimates, using a two-event mark-recapture experiment, the abundance of chinook salmon, Oncorhynchus tshawytscha, that returned to spawn in the Unuk River in 2006.
Download or read book Estimated Abundance of Chinook Salmon Returning to the Nass River B C 1997 microform written by Canada. Department of Fisheries and Oceans. Science and published by Prince Rupert, B.C.: Fisheries and Oceans Canada. This book was released on 1999 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
