Author: Shephard, S., Valbo-Jorgensen, J., Abadía, J., Baigún, C., Doria, C.R.C., Fabré, N.N., Isaac, V.J., Ngor, P.B., Ruffino, M.L., Funge-Smith, S.J.
Publisher: Food & Agriculture Org.
ISBN: 9251335028
Category : Technology & Engineering
Languages : en
Pages : 75
Get Book Here
Book Description
Assessment of data-limited fish stocks is a rapidly evolving topic in marine fisheries, and is supported by an increasing focus on the socio-economic and ecological importance of small-scale fisheries. The challenges in such systems can be compounded in inland fisheries, which are often complex, spatially dispersed and difficult to monitor. This publication reviews the application of empirical indicators and simple size-based models usually used in marine fisheries, but also applicable in inland systems. It presents case study applications for important fisheries in the Amazon River (Brazil), Tonlé Sap River (Cambodia), Paraná River (Argentina) and Lago Bayano (Panama). These studies consider issues including spatial separation of life-history stages, strong modality in population size structure, and fishing gear selectivity. Local scientific experts interpreted trends in stock state. Empirical indicators showed strong decline in size structure and relative abundance for one of the four assessed Tonlé Sap stocks. The length-based spawning potential ratio model suggested that two of the three assessed Amazon Goliath catfish stocks, and the sábalo stock in the Paraná River, were below sustainable spawning potential ratio reference points. The Lago Bayano tilapia stock appeared healthy. The review concludes that data-limited assessment methods developed for marine stocks may provide guidance for the sustainable management of important target species in inland fisheries. The methods tested are probably less applicable in non-selective fisheries where small species are preferred, or in river fisheries with extreme dependence on flood pulses. Important considerations are species life history and spatial distribution, environmental variability, and fishery sampling strategy.
Author: J. A. Gulland
Publisher: Food & Agriculture Org.
ISBN: 9789251031216
Category : Technology & Engineering
Languages : en
Pages : 112
Get Book Here
Book Description
This document reviews the several fish stock assessment methods based on length-frequency analysis. Emphasis is placed on sampling and collection of length-frequency data, to the estimation of population parameters such as growth, mortality and recruitment and the estimation of catch selectivity. Attention is given to the conversion of length to age using age-length keys, slicing length-frequency composition, and using modes. It reviews long-and short-term effects of changes in selection and fishing mortality, and discusses methods for long-term assessments and for short-term projections. The manual gives several examples of the most common methods used and stresses the advantages of using personal computers and the most recent software for data processing and analysis.
Author: Ian G. Cowx
Publisher: Wiley-Blackwell
ISBN: 9780852382240
Category : Technology & Engineering
Languages : en
Pages : 528
Get Book Here
Book Description
Based on an international symposium and workshop hosted by the University of Hull International Fisheries Institute, this new reference includes expert reviews of the advantages and shortcomings of all current techniques and management strategies used in assessment of freshwater fish stocks worldwide. In addition to the core reports, overview papers present a summary of the current status of our knowledge in each of the major subject areas, with a final chapter appraising present and future perspectives on the concept of stock assessment. All contributions are fully illustrated and referenced. Stock Assessment in Inland Fisheries is likely to become the international, standard reference for all fisheries departments--offering a single source of contemporary and definitive information. Moreover, it is also intended to serve as a course text for students learning about freshwater-fisheries management.
Author: Vincent F. Gallucci
Publisher: CRC Press
ISBN: 1000940969
Category : Science
Languages : en
Pages : 538
Get Book Here
Book Description
Stock Assessment: Quantitative Methods and Applications for Small Scale Fisheries is a book about stock assessment as it is practiced. It focuses on applications for small scale or artisanal fisheries in developing countries, however it is not limited in applicability to tropical waters and should also be considered a resource for students of temperate fishery management problems. It incorporates a careful sample design, various mathematical models as a basis for predicting consequences for stock exploitation, and discusses the impact of exploitation on non-targeted species. This was a unique concept involving a collaborative effort between U.S. and host country scientists to address issues of regional and global concern through innovative research. Unlike other books on stock assessment that show mathematical models, this is the only book of its kind that discusses how an assessment is carried out. It looks at the field as a whole and includes sampling, age determination and acoustics. The book represents the culmination of a nine-year program financed by the United States Agency for International Development to provide new or improved methods of stock assessment for artisanal fisheries.
Author: Food and Agriculture Organization of the United Nations
Publisher: Food & Agriculture Org.
ISBN: 925134289X
Category : Social Science
Languages : en
Pages : 120
Get Book Here
Book Description
This catalogue aims to improve the dissemination and outreach of FAO’s knowledge products and overall publishing programme. By providing information on its key publications in every area of FAO’s work, and catering to a range of audiences, it thereby contributes to all organizational outcomes. From statistical analysis to specialized manuals to children’s books, FAO publications cater to a diverse range of audiences. This catalogue presents a selection of FAO’s main publications, produced in 2020 or earlier, ranging from its global reports and general interest publications to numerous specialized titles. In addition to the major themes of agriculture, forestry and fisheries, it also includes thematic sections on climate change, economic and social development, and food safety and nutrition.
Author: Vincent F. Gallucci
Publisher: CRC Press
ISBN: 9781566701518
Category : Science
Languages : en
Pages : 544
Get Book Here
Book Description
Stock Assessment: Quantitative Methods and Applications for Small Scale Fisheries is a book about stock assessment as it is practiced. It focuses on applications for small scale or artisanal fisheries in developing countries, however it is not limited in applicability to tropical waters and should also be considered a resource for students of temperate fishery management problems. It incorporates a careful sample design, various mathematical models as a basis for predicting consequences for stock exploitation, and discusses the impact of exploitation on non-targeted species. This was a unique concept involving a collaborative effort between U.S. and host country scientists to address issues of regional and global concern through innovative research. Unlike other books on stock assessment that show mathematical models, this is the only book of its kind that discusses how an assessment is carried out. It looks at the field as a whole and includes sampling, age determination and acoustics. The book represents the culmination of a nine-year program financed by the United States Agency for International Development to provide new or improved methods of stock assessment for artisanal fisheries.
Author: Daniel D. Hoggarth
Publisher: Food & Agriculture Org.
ISBN: 9789251055038
Category : Business & Economics
Languages : en
Pages : 284
Get Book Here
Book Description
This publication contains guidelines for fish stock assessment and fishery management using the software tools and other outputs developed by the UK Department for International Development's Fisheries Management Science Programme (FMSP) from 1992 to 2004. It includes a CD-ROM with the installation files for each of the four FMSP software tools: LFDA (Length Frequency Data Analysis), CEDA (Catch Effort Data Analysis), YIELD and ParFish (Participatory Fisheries Stock Assessment).
Author: Merrill B. Rudd
Publisher:
ISBN:
Category :
Languages : en
Pages : 141
Get Book Here
Book Description
Many regions of the world have very few stocks assessed, often due to limited data quality or quantity or lack of trained scientists to apply and interpret stock assessments. These same areas with fewer assessments perform worse across fishery management attributes, including research capacity, management, enforcement, and socioeconomics. Some studies have used the limited data available to approximate the status of these “unassessed” stocks and find them to be declining compared to assessed stocks. Global assessments of “unassessed” stocks are informed by many attributes of the stock, one of which is the trend in reported catch to the U.N. Food and Agriculture Organization. These assessments assume that the catch data are accurate, at least in trend if not in magnitude. However, quantifying catch is a major challenge due to commonly misreported sectors such as discards, small-scale, recreational, and illegal, unreported, unregulated fisheries. One approach is to improve catch data by improving monitoring programs or conducting catch reconstructions. Another approach is to collect alternative data types to conduct stock assessments. Stocks that are not assessed because they have the lowest information or research capacity appear more likely to be unsustainable, and further research and management action is required to improve the status of the data- and research-capacity-limited fisheries. This dissertation addresses issues of data quality in the monitoring process and data limitation in the assessment process. Chapter 1 addresses an issue of data quality in asking, “does unreported catch lead to overfishing?” We used simulation analysis to demonstrate that if catch is misreported at a constant rate, surplus production models can still estimate unbiased stock status and would avoid overfishing with effective management. If catch misreporting is increasing over time, stock assessments would recommend harvest limits that would lead to under-exploitation, while decreasing reporting rates lead to over-exploitation. This question is relevant to fisheries around the world dealing with uncertainties in catch reporting in their stock assessment, as well as current debates over the use of catch reconstructions. In Chapter 2 stock assessments are examined for fisheries that only have length composition data and biological information, since it is often easier to collect length measurements than to quantify total catch. Length measurements from samples of the catch, referred to as length composition data, can be contrasted with expected length composition in an unfished state to reveal information about fishing mortality, recruitment, and selectivity. Most data-poor length-based stock assessment methods assume the population is in equilibrium, i.e. that fishing mortality and recruitment have not changed within one generation of the species. In this chapter we present a Length-based Integrated Mixed Effects (LIME) model that relaxes this equilibrium assumption and directly estimates variable fishing mortality and recruitment using the same data inputs as other length-based methods. Using simulation testing we demonstrated LIME performs best for life history types with a maximum age of less than 20 years, and is unbiased across a range of recruitment and fishing mortality patterns, provided individual growth parameters are known. LIME also has the capability of including multiple years of length data, abundance indices, and catch time series when available. LIME is a flexible new tool for stock assessments of fish usually caught as bycatch and other small-scale fisheries. Chapter 3 applies LIME and the equilibrium-based Length-Based Spawning Potential Ratio (LB-SPR) methods to assess a medium-lived Costa Rican spotted rose snapper, Lutjanus guttatus, and short-lived Kenyan rabbitfish, Siganus sutor. LIME estimated the Costa Rican snapper fishery to be overfished in the most recent year of data after a period of full exploitation, whereas LB-SPR estimated more variability in stock status throughout the time series but the fishery was above the target reference point in the most recent year of data. LIME estimated the rabbitfish fishery to have undergone a period of overexploitation in the late 1990s and early 2000s, but fishing mortality has continually decreased over time resulted in a recovered stock in the most recent year of data. Alternatively, LB-SPR estimated the stock slightly less than the SPR target. Chapter 3 presented the first empirical LIME assessment and comparison with a commonly-used alternative method, and presented guidelines for future LIME applications.
Author: Food and Agriculture Organization of the United Nations
Publisher: Food & Agriculture Org.
ISBN: 9251336490
Category : Technology & Engineering
Languages : en
Pages : 58
Get Book Here
Book Description
The Second Advisory Roundtable on the Assessment of Inland Fisheries was convened in partnership with United States Geological Service (USGS), from 25 to 27 November 2019. It reviewed the progress of work that had been initiated as a response to the recommendations of the “Advisory Roundtable on the Assessment of Inland Fisheries” that was convened in partnership with the United States Geological Service (USGS) and Michigan State University (MSU) in FAO Rome, from 8 to 10 May 2018. The Second Roundtable covered two aspects of the assessment of inland fisheries. As its first task, the Roundtable reviewed a threat mapping framework developed by USGS and the University of Florida, which seeks to provide a robust assessment method for inland fisheries and the associated ecosystems/basins upon which they depend. This is intended to support the management of aquatic systems and the continued delivery of ecosystem services. The status map that the analysis provides is a visual (and quantifiable) relative indication of the levels of anthropogenic and natural environmental pressures to inland fisheries at the basin or sub-basin level. Five major threats to inland fisheries (and their 21 sub-threat categories) were scored according to global studies and modeling.
Author: Giuseppe Scarcella
Publisher: Frontiers Media SA
ISBN: 283252009X
Category : Science
Languages : en
Pages : 294
Get Book Here
Book Description
