Download or read book Simulation Models for Estimating Productivity and Trade offs in the Data limited Fisheries of New South Wales Australia written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent shifts towards ecosystem based fisheries management (EBFM) around the world have necessitated consideration of effects of fishing on a larger range of species than previously. Non-selective multispecies fisheries are particularly problematic for EBFM, as they can contribute to erosion of ecosystem structure. The trade-off between catch of productive commercial species and abundance of low-productivity species is unavoidable in most multispecies fisheries. A first step in evaluation of this trade-off is estimation of productivity of different species but this is often hampered by poor data. This thesis develops techniques for estimating productivity for data-limited species and aims to help clarify EBFM policy objectives for the fisheries of New South Wales (NSW), Australia. It begins with development of an age-structured model parameterised in terms of optimal harvest rate, UMSY. UMSY is a measure of productivity, comparable among species and easily communicated to managers. It also represents a valid threshold for prevention of overfishing. The model is used to derive UMSY for 54 Atlantic fish stocks for which recruitment parameters had previously been estimated. In most cases, UMSY was strongly limited by the age at which fish were first caught. However, for some species, UMSY was more strongly constrained by life history attributes. The model was then applied to twelve species of Australian deepwater dogshark (Order Squaliformes), known to have been severely depleted by fishing. Results showed that the range of possible values of UMSY for these species is very low indeed. These findings enabled a preliminary stock assessment for three dogsharks (Centrophorus spp.) currently being considered for threatened species listing. Preliminary results suggest they have been overfished and that overfishing continues. Finally, an Ecopath with Ecosim ecosystem model, representing the 1976 NSW continental slope, is used to illustrate trade-offs in implementation of fish.
Download or read book Canadian Journal of Fisheries and Aquatic Sciences written by and published by . This book was released on 2010 with total page 742 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Marine Freshwater Research written by and published by . This book was released on 2013 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modelling and Quantitative Methods in Fisheries Second Edition written by Malcolm Haddon and published by CRC Press. This book was released on 2001-05-31 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: With numerous real-world examples, Modelling and Quantitative Methods in Fisheries, Second Edition provides an introduction to the analytical methods used by fisheries’ scientists and ecologists. By following the examples using Excel, readers see the nuts and bolts of how the methods work and better understand the underlying principles. Excel workbooks are available for download from CRC Press website. In this second edition, the author has revised all chapters and improved a number of the examples. This edition also includes two entirely new chapters: Characterization of Uncertainty covers asymptotic errors and likelihood profiles and develops a generalized Gibbs sampler to run a Markov chain Monte Carlo analysis that can be used to generate Bayesian posteriors Sized-Based Models implements a fully functional size-based stock assessment model using abalone as an example This book continues to cover a broad range of topics related to quantitative methods and modelling. It offers a solid foundation in the skills required for the quantitative study of marine populations. Explaining important and relatively complex ideas and methods in a clear manner, the author presents full, step-by-step derivations of equations as much as possible to enable a thorough understanding of the models and methods.
Download or read book Three Essays on Estimation of Applied Economic Models in Fisheries written by Christopher Burns and published by . This book was released on 2014 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fishery managers face many challenges when setting effective policies. This includes working with fisherman to set the total allowable catch (TAC), preventing overfishing, and monitoring the status of a fishing industry based on imperfect data. This dissertation focuses on the last two issues. In particular we focus on how measurement error and estimation issues can impact fishery policy using two common economic models, the stochastic frontier model and the Schaefer production model. Both of these models use production data on inputs and outputs to estimate a production function. Using panel data from the Mid-Atlantic surfclam fishery from 2001-2009, Chapters 2 and 3 examine measurement error correction methods that policy makers can use when instrumental variables are not available. We examine this particular fishery because both logbook data from vessels, and scientific estimates of the biomass are available. In Chapters 2 and 3 we make use of estimates of the measurement error variance, and apply a simulation based correction method known as simulation extrapolation (SIMEX). SIMEX is a simulation based method for reducing bias in parameter estimates caused by measurement error. After estimating both models under a naive analysis, SIMEX is used to obtain less biased estimates of technical efficiency, production and biological parameters. In the last chapter we revisit the stochastic frontier model, estimating both a maximum likelihood and Bayesian model. We conclude the dissertation by discussing the results from each chapter, and their implications for fishery policy.
Download or read book Quantitative Fisheries Stock Assessment written by R. Hilborn and published by Springer Science & Business Media. This book was released on 1992 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book really began in 1980 with our first microcomputer, an Apple II +. The great value of the Apple II + was that we could take the computer programs we had been building on mainframe and mini-computers, and make them available to the many fisheries biologists who also had Apple II + 's. About 6 months after we got our first Apple, John Glaister came through Vancouver and saw what we were doing and realized that his agency (New South Wales State Fisheries) had the same equipment and could run the same programs. John organized a training course in Australia where we showed about 25 Australian fisheries biologists how to use microcomputers to do many standard fisheries analyses. In the process of organizing this and sub sequent courses we developed a series of lecture notes. Over the last 10 years these notes have evolved into the chapters of this book.
Download or read book Evaluating the Performance and Applicability of State space Stock Assessment Models written by Emily Morgan Liljestrand and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fisheries stock assessment models are used to estimate population demographics and dynamics such as abundance, biomass, and fishing mortality from input fishery data including total catch, composition of catch, and fishing effort. A goal of stock assessment is to accurately quantify population and fishery dynamics so stocks can be managed to achieve fishery objectives and long-term sustainability. Accurate and precise model estimates can be attained by using models and techniques that account for ecological complexity like variability in quantities across ages, years, or regions without overparameterization. The state-space framework is one such statistical technique that may allow for incorporating more stochasticity such that the model can better reflect reality. The state-space modeling framework assumes that unobserved "states" develop over time due to process error modeled as a random effect and that observed data have expected values based on these states but differ from expectations due to observation error.State-space stock assessment models (SSSAM) have experienced an outpouring of research and application in the past decade as computation processing power and novel software has facilitated the approximation of the high-level integrals necessary for SSSAM. SSSAM allows for several time-varying processes in recruitment, numbers at age, mortality, selectivity, and catchability, and has become an essential part of the contemporary fisheries modeling toolbox. With their swift advancement, it is important to understand best practices of applying state-space stock assessment models, and how data availability, the variability of process or observation error, and model structure may influence model results and accuracy.In Chapter 1 I built an age-based state-space stock assessment model that used fisheries dependent data, rather than fisheries independent surveys, as an index of abundance and was applied to Lake Michigan lake whitefish (Coregonus clupeaformis). The model predicted greater℗ abundance and lower mortality compared to the non-state-space model and domed rather than asymptotic selectivity. The state-space model also had reduced retrospective patterns in recruitment. Chapters 2 and 3 each used a simulation-estimation framework to generate catch and index data using a state-space stock assessment that assumed process variability in recruitment, expected survival (abundance), and selectivity. Simulations were based on a Gulf of Maine haddock (Melanogrammus aeglefinus) model and assumed different degrees of process and observation variance (Chapter 2) or assumed observation error likelihood distributions for the proportions at age (Chapter 3) to generate data. Simulated data were input into several estimation models with alternative assumptions about contributing sources of process variability and/or observation error distributions. The results show that state-space models which assume several sources of process variability can produce unbiased estimates even when processes are constant over time. The state-space models were able to estimate process variance in several stochastic processes under a broad range of true values. However, assuming variability in expected survival when it is deterministic can lead to the model not converging. Unbiased results are achieved when the observation likelihood is structured to account for inter-age correlation and overdispersion though such a framework may have difficulty allocating variance between process and observation sub-models.The concluding chapter places this work in the context of other age-based stock assessment models and argues for the inclusion of state-space in the modeling toolbox, as they can account for multiple time-varying processes and be used in a broad range of data contexts. This work provides a blueprint for where and how SSSAM may be best utilized in the future, particularly with data limited or data poor stocks and in cases where the process variance is unknown and should be estimated within the model.
Download or read book A Numerical Model for Estimating Fish Productivity of Large Lakes written by Sirinimit Boonyuen and published by . This book was released on 1986 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimating Persistence of Fished Populations with Limited Data written by Michael Robert O'Farrell and published by . This book was released on 2005 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Agrindex written by and published by . This book was released on 1995 with total page 964 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Review of Assessment Tools for Data limited Fisheries written by Z. Y. Zhang and published by . This book was released on 1999 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Developing a Data poor Stock Assessment Model for New Zealand Bycatch Species written by Callum Templeton and published by . This book was released on 2016 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigated methods pertaining to the assessment of data-poor fishery stocks within New Zealand. Recent modelling approaches (termed ‘N-mixture’) have appeared in the ecological literature that enable simultaneous estimation of abundance and detectability (gear efficiency in a fisheries context) from count data corresponding to a population of interest. This approach forms part of the quantitative risk assessment framework known as Sustainability Assessment for Fishing Effects, which has been applied to a range of species in Australian fisheries. There is potential for application of such methods in New Zealand, where an estimated 80% of fish stocks lack assessment under the Quota Management System. Various models were developed as part of this study in order to obtain quantitative estimates relating to catchability and abundance. These involved a mixture of statistical distributions (log-normal, Poisson, and binomial) and were implemented in the R and JAGS software. A range of simulations were devised to produce artificial data sets for model validation and analysis purposes. Models were analysed using a Bayesian hierarchical approach in order to estimate the parameters of interest. The models under investigation were also applied to red gurnard (Chelidonichthys kumu) data from the GUR 1 stock management area in northeastern New Zealand, to provide a case study for real-world applicability. Model validation revealed that recovering estimates of gear efficiency and abundance was possible using the approach considered here. Analysis simulations provided information regarding the potential sources of bias, variability and incompatibility arising from assumptions in model specification and data generation. These findings were also considered in the context of application to red gurnard. The most important issues highlighted by this study include the role of over-dispersion on modelling and data requirements, handling zeroinflated data sets, and bias introduced from catch reporting procedures in commercial fisheries within New Zealand. The results of this study provide an important first step in assessing data-poor stocks, providing a cost-effective means of obtaining key fishing parameters without significant data requirements. Further research into this area will enable these findings to be applied alongside other methods in order to gauge the sustainability of fishing impacts on bycatch species.
Download or read book Models for an Ecosystem Approach to Fisheries written by Éva E. Plagányi and published by Food & Agriculture Org.. This book was released on 2007 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report reviews the methods available for examining ecosystem dynamics and assessing the impact of interactions between ecosystems and human activities, particularly fisheries, and their implications for marine fisheries management. It focuses on the currently available models representative of general types such as bionergetic models, predator-prey models and minimally realistic models; with short descriptions given of model parameters, assumptions and data requirements. It discusses the advantages, disadvantages and limitations of each of the approaches; and concludes with some recommendations for the future development of multi-species and ecosystem models.
Download or read book Valuing Ecosystem Services written by National Research Council and published by National Academies Press. This book was released on 2005-05-14 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nutrient recycling, habitat for plants and animals, flood control, and water supply are among the many beneficial services provided by aquatic ecosystems. In making decisions about human activities, such as draining a wetland for a housing development, it is essential to consider both the value of the development and the value of the ecosystem services that could be lost. Despite a growing recognition of the importance of ecosystem services, their value is often overlooked in environmental decision-making. This report identifies methods for assigning economic value to ecosystem servicesâ€"even intangible onesâ€"and calls for greater collaboration between ecologists and economists in such efforts.
Download or read book The Regional Impacts of Climate Change written by Intergovernmental Panel on Climate Change. Working Group II. and published by Cambridge University Press. This book was released on 1998 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cambridge, UK : Cambridge University Press, 1998.
Download or read book Climate Change 2014 written by Groupe d'experts intergouvernemental sur l'évolution du climat and published by . This book was released on 2015 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
