Download or read book Modeling and Stock Assessment of Prince William Sound Pacific Herring written by Trevor A. Branch and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Report on the ongoing monitoring of the Pacific herring population in the Prince William Sound in the aftermath of the Exxon Valdez Oil Spill. The report outlines ongoing projects including annual stock assessments using a Bayesian model, an assessment of disease data, analysis of factors affecting natural mortality and recruitment, a study on changes in spawning patterns, and testing of hypotheses for changes in spawning timing.
Download or read book Stock Assessment and Management of Pacific Herring in Prince William Sound Alaska 1988 written by Timothy T. Baker and published by . This book was released on 1990 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling the Population Dynamics of Prince William Sound Herring written by Trevor A. Branch and published by . This book was released on 2018 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: A stock-age assessment model of Prince William Sound Pacific herring, utilizing data collected from 2102-2017. It was determined that the use of a Bayesian model to be an effective means of estimating ongoing biomass trends in the herring population.
Download or read book Stock Assessment and Management of Pacific Herring in Prince William Sound Alaska 1990 written by Timothy T. Baker and published by . This book was released on 1991 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stock Assessment and Management of Pacific Herring in Prince William Sound Alaska 1989 written by Timothy T. Baker and published by . This book was released on 1991 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interrelationships of Pacific Herring Clupea Pallasi Populations and Their Relation to Large scale Environmental and Oceanographic Variables written by Erik Hamilton Williams and published by . This book was released on 1999 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recruitment estimates for Pacific herring, Clupea pallasi, populations in the Bering Sea and Northeast Pacific Ocean are highly variable, difficult to forecast, and crucial for determining optimum harvest levels. Age-structured population models for annual stock assessments of the sac-roe fisheries rely on fishery and survey age composition data tuned to an auxiliary survey of total biomass. In Chapter 1, the first age-structured model for Norton Sound herring was developed similarly to existing models. Estimates of variability from age-structured stock assessment models for Pacific herring are often not calculated. In Chapter 2, a parametric bootstrap procedure using a fit of the Dirichlet distribution to observed age composition data was developed as a quick and easy method for computing error estimates of model estimates. This bootstrap technique was able to capture variability beyond that of the multinomial distribution. This technique can provide estimates of variability for existing population models with age composition data requiring little change to the original model structure. Recruitment time series from Pacific herring stock assessment models for 14 populations in the Bering Sea and Northeast Pacific Ocean were analyzed for links to the environment. For some populations, recruitment series were extended backward in time using cohort analysis. In chapter 3, correlation and multivariate cluster analyses were applied to determine herring population associations. There appear to be four major herring groups: Bering Sea, outer Gulf of Alaska, coastal Southeast Alaska, and British Columbia. These associations were combined with an exploratory correlation analysis of environmental data in chapter 4. Appropriate time periods for environmental variables were determined for use in Ricker type environmentally dependent spawner-recruit forecasting models. Global and local scale environmental variables were examined in forecasting models, resulting in improvements in recruitment forecasts compared to models without environmental data. The exploratory correlation analysis and best fit models, determined by jacknife error prediction, indicated temperature data corresponding to the year of spawning resulted in the best forecasting models. The Norton Sound age-structured model, parametric bootstrap procedure, and recruitment forecasting models serve as enhancements to the decision process of managing Pacific herring fisheries.
Download or read book Forecast of the Pacific Herring Biomass in Prince William Sound Alaska 1993 written by Fritz Funk and published by . This book was released on 1994 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: "An egg structured assessment (ASA) model is used to forecast the abundance of herring expected to return to spawn in Prince William Sound in 1993. The ASA model develops 1973-92 biomass estimates by smoothing differences in abundance trends suggested by spawn deposition surveys, aerial milt surveys, and the time series of purse seine, gillnet, and spawning age composition samples"--Page vi.
Download or read book Analysis and Comparison of Age structured Assessment Models for Two Pacific Herring Populations written by Peter-John F. Hulson and published by . This book was released on 2007 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Substantial research has been devoted to identify causes for decline the of Prince William Sound (PWS) Pacific herring in the early 1990's because of the proximity to the 1989 Exxon Valdez oil spill (EVOS). A potential source for decline has been identified with the isolation of disease in the PWS population. There have been limited investigations of PWS Pacific herring population dynamics related to other stocks in the Gulf of Alaska. The objective of this thesis was to compare observations and age-structured assessment (ASA) model results between PWS and Sitka Sound Pacific herring. Data conflicts were evaluated in the PWS ASA model and indicate that hypotheses about natural mortality in the four years subsequent to EVOS depend on the type and weighting of population indices. In Sitka, the ASA model was used to show that time-dependent natural mortality can be estimated. Comparison between PWS and Sitka indicated that age structure and recruitment have been comparable, but abundance indices and weight-at-age data have not been similar after 1993. The differences identified in this thesis between PWS and Sitka imply uniqueness in natural mortality and condition within each Pacific herring population"--Leaf iii.
Download or read book Modeling Population Collapse and Recovery in Herring written by John T. Trochta and published by . This book was released on 2021 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: Population collapse in forage fish occurs both naturally and due to overfishing, and is a challenge to sustainable fisheries management. Sustained low abundance can result in prolonged fishery closures and impact the abundance of other species via predation or competition. The time taken to recover from collapse is determined by uncertain factors that control population dynamics and can widely vary between populations. Herring (Clupea spp.) are a major group of forage fishes with numerous populations throughout the Northern Hemisphere, that have sustained commercial fisheries for centuries and indigenous fishers for far longer, and support ecologically and economically valuable species including various pinnipeds, whales, seabirds, and predatory fishes. Herring populations across the world have shown varying durations of population collapse since the start of industrial fishing while hypotheses of the underlying factors have been underdetermined across and within individual populations. The Pacific herring (Clupea pallasii) population in Prince William Sound, Alaska is a modern enduring example of prolonged population collapse whose population dynamics remain largely uncertain and unpredictable despite intensive monitoring and modeling. In this dissertation, I explore and evaluate factors that potentially influence population collapse and recovery within herring. My overarching goal is to better inform the population dynamics of herring and more specifically improve the Bayesian stock assessment model of Prince William Sound herring. In Chapter 1, I conducted a meta-analysis on time series collected for 64 populations worldwide to statistically characterize population collapse and recovery in herring and model predictors of recovery times in adult biomass and recruitment. After collapse, herring populations recovered in 11 years on average, with a few populations remaining collapsed for multiple decades. Amongst populations, recovery time duration did not coincide with fishery closures, which occurred at low abundance in most Pacific herring populations but no Atlantic herring populations. Faster recovery in biomass was best associated with higher average recruitment and higher oceanographic variability in both sea surface height anomalies and sea surface temperatures. In Chapter 2, I modeled ecological factors impacting natural mortality and recruitment in Prince William Sound herring using a custom-built Bayesian age-structured stock assessment model. Support for individual factors was evaluated using multiple Bayesian model selection criteria and alternative modeling assumptions about the ecological data representing these factors. There was strongest evidence for effects on herring natural mortality from pink salmon abundance in Prince William Sound had the most broad and consistent support. Statistical support differed by the type of selection criteria, model assumptions regarding covariates, and time period modeled, resulting in generally weak evidence for most individual effects and the suggestion that results are sensitive to model flexibility. In Chapter 3, I developed a novel modeling framework and conducted a simulation study to test the usefulness of age-specific antibody, or seroprevalence, data in assessing the impact of disease-associated mortality on herring, for use in stock assessment models. Viral hemorrhagic septicemia virus (VHSV) in Prince William Sound herring is used as a case study due to its association with fish kills and well-established ecological principles for its epizootiology from extensive monitoring of VHSV in herring populations. I found that incorporating seroprevalence data within stock assessment can accurately inform infection history and disease mortality and improve population estimates. The first real application of age-specific VHSV seroprevalence is demonstrated with the Prince William Sound herring stock assessment. While motivated from VHSV in herring, these models can be easily adapted to different host populations and pathogens and I present advice for future applications of disease data within stock assessment.
Download or read book Age Structured Analysis of Pacific Herring from Norton Sound Alaska written by Erik H. Williams and published by . This book was released on 1996 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Age-structured assessment models are used for many exploitable herring stocks in Alaska in order to forecast the abundance of returning herring. The purpose of this study is to determine if an age-structured assessment model could be developed for Norton Sound herring. Commercial catch and sampling data for Norton Sound herring were obtained from the Alaska Department of Fish and Game. Natural mortality estimates were obtained from analysis of life history parameters. Initial starting values for the age-structured model weere obtained from cohort analysis. Two types of models, with and without a pooled age group, were fit to the data. A parametric bootstrap analysis utilizing a beta distribution fit to observed age compositions was performed in order to obtain standart deviations of the estimates. Model fits indicated that inclusion of a pooled age group (10+) worked best. The fit of this model to the data is comparable to previous age-structured assessments of Alaska herring stocks." -- from the Abstract.
Download or read book Prince William Sound Commercial Harvest of Pacific Herring 1984 1987 written by Gene J. Sandone and published by . This book was released on 1988 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analysis of the Pacific herring (Clupea harengus pallasi) harvest in Prince William Sound (southcentral Alaska) during the management years 1984-87.
Download or read book Growth of Pacific Herring in Prince William Sound Alaska from 1973 Through 1987 written by Fritz Funk and published by . This book was released on 1989 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pacific Herring Juvenile Winter Survival and Recruitment in Prince William Sound written by Fletcher Sewall and published by . This book was released on 2020 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Small pelagic fish abundances can vary widely over space and time making them difficult to forecast, partially due to large changes in the number of individuals that annually recruit to the spawning population. Recruitment fluctuations are largely driven by variable early life stage survival, particularly through the first winter for cold temperate fishes. Winter survival may be influenced by juvenile fish size, energy stores, and other factors that are often poorly documented, which may hamper understanding recruitment processes for economically and ecologically important marine species. The goal of this research was to improve understanding of recruitment of Pacific herring (Clupea pallasii) within Prince William Sound (PWS) through recruitment modeling and by identifying factors influencing winter survival of young-of-the-year (YOY) herring. Towards this end, my dissertation addresses three specific objectives: 1) incorporate oceanographic and biological variables into a herring recruitment model, 2) describe patterns in growth and condition of PWS YOY herring and their relationship to winter mortality risks, and 3) compare the growth, condition, swimming performance, and mortality of YOY herring that experience different winter feeding levels. In the recruitment modeling study, annual mean numbers of PWS herring recruits-per-spawner were positively correlated with YOY walleye pollock (Gadus chalcogrammus) abundance in the Gulf of Alaska, hence including a YOY pollock index within a standard Ricker model improved herring recruitment estimates. Synchrony of juvenile herring and pollock survival persisted through the three-decade study period, including the herring stock collapse in the early 1990s. While the specific mechanism determining survival is speculative, size-based tradeoffs in growth and energy storage in PWS YOY herring indicated herring must reach a critical size before winter, presumably to reduce size-dependent predation. Large herring switched from growth to storing energy, and ate more high-quality euphausiid prey, which would delay the depletion of lipid stores that compelled lean herring to forage. Lipid stores were highest in the coldest year of the seven-year field study, rather than the year with the best diets. With diets controlled in a laboratory setting, spring re-feeding following restricted winter diets promoted maintenance of size and swimming ability, but had little effect on mortality rates compared to fish continued on restricted rations. Declines in gut mass, even among fully fed herring, and low growth potential suggest limited benefits to winter feeding. Mortalities due to food restriction compounded by disease were highest among herring that fasted through winter months, and among small herring regardless of feeding level. Taken together, these findings illustrate the importance of achieving a critical size and high lipid stores in the critical period before winter to promote YOY herring winter survival and ultimately recruitment.
Download or read book Physical and Biological Factors Affecting Pacific Herring Egg Loss in Prince William Sound Alaska written by Christopher N. Rooper and published by . This book was released on 1996 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: The biomass of Prince William Sound herring (Clupea pallasi) is estimated from egg deposition surveys. Because surveys occur after spawning, a correction for egg loss is required. I constructed ANOVA models based on environmental factors to estimate the egg loss correction in 1990-1991 and 1994-1995. The models explained 52% to 85% of the data variation. Depth of spawn was the primary factor determining egg loss, and air exposure could be substituted for depth. The correction factor was estimated at 33%. The total loss of eggs from spawning to hatching ranged from 67.40% to 100% averaging 76.06%, Two processes affecting egg loss, wave action and fish predation, were also examined. Typical wave energies were not found to contribute significantly to egg loss, but a threshold wave energy may exist beyond which egg loss is high. Consumption of eggs by greenling (Hexagrammidae) was estimated at 2.2% to 8.5% of the total spawn.
Download or read book Fishery Stock Assessment Models written by Fritz Funk and published by Alaska Sea Grant College Program. This book was released on 1998 with total page 1060 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume bring fisheries modelers up to date on stock assessment modeling as a research tool. It has 55 peer-reviewed papers from all parts of the world, presented at the 1997 symposium Fishery Stock Assessment Models for the 21st Century, in Anchorage, Alaska.
Download or read book Stock Assessment of Pacific Herring Bristol Bay Alaska written by Stephen M. Fried and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Genetic Stock Structure of Herring in Prince William Sound written by Sharon L. Wildes and published by . This book was released on 2018 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Examination of the genetic stock structure of Pacific herring within Prince William Sound, in comparison to those from ajacent geographic locations.
