Download or read book Evaluation of Recent Changes in the Population Dynamics of Southern Gulf Herring written by G. H. Winters and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Landings from this stock complex decreased from peak levels of 300,000 m tons in 1970 to a low of 37,200 m tons in 1974. Research studies (Winters and Hodder 1975) have revealed that the precipitous decline in abundance during the 1970's was due to a combination of moderate growth overfishing and successively poor recruitment to both spawning components (spring and fall) following two very large but apparently anomalous year-classes produced in the late 1950's. More recent studies (Winters et al. 1977, Winters 1978) have indicated divergent recruitment patterns in the two spawning components during the last decade, resulting in a shift in predominance towards spring-spawners"--Introduction.
Download or read book Population Dynamics of the Southern Gulf of St Lawrence Herring Stock Complex and Implications Concerning Its Future Management written by G. H. Winters and published by 1975 [c1977]. This book was released on 1975 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Population Dynamics of the Atlantic Herring in the Gulf of Maine written by Vaughn Carleton Anthony and published by . This book was released on 1972 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Canadian Journal of Fisheries and Aquatic Sciences written by and published by . This book was released on 1996 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the Alaska Herring Symposium February 19 21 1980 Anchorage Alaska written by Brenda Melteff and published by . This book was released on 1981 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Canadian Technical Report of Fisheries and Aquatic Sciences written by and published by . This book was released on 1980 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Canadian Special Publication of Fisheries and Aquatic Sciences written by and published by . This book was released on 1982 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fishery Bulletin written by and published by . This book was released on 2000 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bottom Trawl Surveys written by W. G. Doubleday and published by Department of Fisheries and Oceans = Ministère des pêches et des océans. This book was released on 1981 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Collected Reprints written by Southwest Fisheries Center (U.S.) and published by . This book was released on 1980 with total page 1074 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Evaluation of the Current Status of Southern Gulf Herring written by G. H. Winters and published by . This book was released on 1980 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Catches from the southern Gulf of St. Lawrence herring stock complex declined from 52,000 mt in 1978 to 45,900 mt in 1979. This decline can be primarily attributable to the voluntary closure of the "Edge" fishery due to the presence of large quantities of small herring ... these analyses indicate 2+ biomass of this stock-complex has remained relatively stable at about 450,000 mt and that recruitment in most recent years has been improving"--Abstract.
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 Population Modelling Results for the Assessment of Atlantic Herring Clupea Harengus Stocks in the Southern Gulf of St Lawrence NAFO Division 4T to 2015 written by D. P. Swain and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Marine Fisheries Review written by and published by . This book was released on 1975 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Catch and effort data used in the assessment of herring populations in the southern Gulf of St Lawrence written by and published by . This book was released on 2002 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Federal Register written by and published by . This book was released on 2013-08 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
