Consulta: subjectFacets:"Survey data"
Registros recuperados: 17
Data/hora: 01/06/2024 16:24:53

Impact d’une obligation de débarquement sur les dynamiques couplées écosystème-pêcheurs : approche par modélisation individu-centrée appliquée à la Manche orientale
Provedor de dados: 5
Autores: Bourdaud, Pierre.
The objective of this thesis was to anticipate the effects if the EU Landing Obligation (LO) implemented since the beginning of 2015 in the Eastern English Channel (EEC). To achieve these objectives, it was planned to: i) better understand seasonal spatial distribution of commercial species using on-board commercial vessels observation data, ii) compare them with the fine scale fishing effort distribution of EEC bottom otter trawlers (OTB), and iii) develop an individual-based model of fleet-dynamics, DSVM, to be integrated within the ecosystem model OSMOSE to simulate a LO. The usefulness of on-board observation data was proved for a main part of a species sample, using validation from the literature and a geostatistical indicator. Then the comparison of...
Tipo: Text
Palavras-chave: Distribution spatiale; Saisonnalité; Données commerciales; Données de campagnes scientifiques; Manche Orientale; Effort de pêche; Assemblages d’espèces cibles; Obligation de débarquement; Modèle individu-centré; Dynamiques des flottilles; Spatial distribution; Seasonality; Commercial data; Survey data; Eastern English Channel; Fishing effort; Target species assemblages; Landing obligation; Individual-based model; Fleet dynamics.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00440/55135/56603.pdf

Combining time trends in multiple metrics for identifying persistent changes in population processes or environmental stressors
Provedor de dados: 5
Autores: Trenkel, Verena; Rochet, Marie-joelle.
P&gt;1. Metrics have become a standard way for summarizing environmental monitoring results. Different metrics react differently to natural variations and human-induced stressors. We suggest that combined analysis of time trends in selected biological metrics allows identification of biological processes (e.g. individual growth, mortality or recruitment) that have changed (increased or decreased) persistently. Alternatively, time trends in the abundance of sensitive species could indicate changes in environmental stressors. 2. We calculate the joint likelihood of time trends in three metrics and use it to evaluate the evidence in the data for different combinations of metric time trends. A simulation study provides guidelines for interpreting...
Tipo: Text
Palavras-chave: Generalized additive model; Indicators; Likelihood principle; Quadratic programming; Survey data.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00008/11926/8988.pdf

Large-scale distribution of three deep-water squaloid sharks: Integrating data on sex, maturity and environment
Provedor de dados: 5
Autores: Moura, Teresa; Jones, Emma; Clarke, Maurice W.; Cotton, Charles F.; Crozier, Paul; Daley, Ross K.; Diez, Guzman; Dobby, Helen; Dyb, Jan E.; Fossen, Inge; Irvine, Sarah B.; Jakobsdottir, Klara; Lopez-abellan, Luis J.; Lorance, Pascal; Pascual-alayon, Pedro; Severino, Ricardo B.; Figueiredo, Ivone.
Deep-water sharks exhibit species-specific reproductive strategies, which include segregation by sex, size and reproductive stage. However, due to the wide spatial distribution of most species, available information, usually collected at a regional scale, is usually not adequate to infer species reproductive spatial dynamics. This study draws together information on the distribution of reproductive stages of three species of squaliform sharks: Portuguese dogfish Centroscymnus coelolepis (Somniosidae), leafscale gulper shark Centrophorus squamosus (Centrophoridae) and birdbeak dogfish Deania calcea (Centrophoridae), gathering data from several geographical areas from the Atlantic, Indian and Pacific Oceans. For each species we analysed the sex ratio and the...
Tipo: Text
Palavras-chave: Commercial fishery data; Deep-sea; Life stage; Population structure; Survey data.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00188/29902/29420.pdf

Do population and community metrics tell the same story about recent changes in Northern Mediterranean fish communities?
Provedor de dados: 5
Autores: Rochet, Marie-joelle; Trenkel, Verena; Gil De Sola, Luis; Politou, Chrissi-yianna; Tserpes, George; Bertrand, Jacques.
This document presents a comparative study of human impacts on the length-structure of fish communities across North-Mediterranean ecosystems. We use survey data to examine trends in length-based metrics and their consistency within and among the two levels of organisation populations and communities, and to suggest interpretations of observed trend combinations. We start from a set of population processes potentially affected by human pressures: fishing will induce mortality especially in target species, whereas the hydrological environment and eutrophication potentially affect recruitment and individual growth. How population changes will be reflected at the community level is expected to depend on community evenness. Based on this expectation, a...
Tipo: Text
Palavras-chave: Community metrics; Ecosystem approach to fisheries; Fish community; Length-based metrics; Mediterranean; Survey data.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/00133/24377/22389.pdf

Inferring the annual, seasonal, and spatial distributions of marine species from complementary research and commercial vessels’ catch rates
Provedor de dados: 5
Autores: Bourdaud, Pierre; Travers-trolet, Morgane; Vermard, Youen; Cormon, Xochitl; Marchal, Paul.
The objective of this study is to analyse at fine scale the annual, seasonal and spatial distributions of several species in the Eastern English Channel (EEC). On the one hand, data obtained from scientific surveys are not available all year through, but are considered to provide consistent yearly and spatially resolved abundance indices. On the other hand, on-board commercial data do cover the whole year, but generally provide a biased perception of stock abundance. The combination of scientific and commercial catches per unit of effort (CPUEs), standardized using a delta-generalized linear model, allowed to infer spatial and monthly dynamics of fish distributions in the EEC, which could be compared with previous knowledge on their life cycles....
Tipo: Text
Palavras-chave: Commercial data; Eastern English Channel; Seasonality; Spatial distribution; Survey data.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00387/49805/50385.pdf

Are commercial logbook and scientific CPUE data useful for characterizing the spatial and seasonal distribution of exploited populations? The case of the Celtic Sea whiting
Provedor de dados: 5
Autores: Verdoit, Marion; Pelletier, Dominique; Bellail, Robert.
A statistical approach is proposed to utilize the information contained both in scientific surveys and commercial fishing logbooks, in order to determine spatial and temporal distributions of recruiting and spawning fish of exploited populations. The approach is based on multivariate descriptive methods including ordination methods and classification techniques. A typology involving a principal component analysis (PCA), followed by a hierarchical ascending classification (HAC), is applied to both scientific and commercial data. PCA that accounts for spatial and temporal contiguities were performed. These analyses allow to compare structures observed at global and local scales, with those observed without focusing on a particular scale. The method is...
Tipo: Text
Palavras-chave: Contiguity analysis; Cluster analysis; Factorial analysis; Atlantic Ocean; Whiting; Survey data; Commercial catch and effort data; Stock assessment; Bottom trawl survey design.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2005/publication-335.pdf

Analysing Family Farm Succession: A Probit and a Competing Risk Approach
Provedor de dados: 31
Autores: Glauben,   Thomas; Tietje,   Hendrik; Weiss,   Christoph R.
The present study examines family and farm characteristics affecting the choice and the timing of intergenerational farm transfers. Using survey data which are linked to accounting data for 272 farms in Northern Germany, we use a probit approach to examine whether specific farm and family characteristics are related to the likelihood of succession within a given period. We go beyond the existing literature by applying a competing risk approach to study the process and thus the timing, respectively of the two competing events – succession or exit from farming. We find that farm characteristics significantly influence succession considerations to the extent that they affect the value of the farm for the potential successor.
Tipo: Conference Paper or Presentation
Palavras-chave: Intrafamily succession; Survey data; Competing risk; Farm Management; Q12; J26.
Ano: 2005
URL: http://purl.umn.edu/24699

Intergenerational Succession on Family Farms: Evidence from Survey Data
Provedor de dados: 31
Autores: Glauben,   Thomas; Tietje,   Hendrik; Weiss,   Christoph R.
This study examines family farms and characteristics affecting farm succession. Based on a farm survey, three aspects of succession are analysed in the paper: the probability of family succession; the likelihood of having a successor designated; and the timing of succession. Large and specialised farms are more likely to be transferred within the family and to have appointed a successor. The number of family members, as well as the experience of farm operator, is also significantly related to the succession behaviour. The probabilities of succession, and of having a successor, first increase with age and then decline again. Furthermore, timing of succession is delayed as the farm holder ages, suggesting most farm operators' succession plans to be...
Tipo: Conference Paper or Presentation
Palavras-chave: Farm succession; Survey data; Econometric analysis; Farm Management.
Ano: 2002
URL: http://purl.umn.edu/24918

Determinants of Decision to Pay a Price Premium for Modified Food by Consumers of the Republic of Korea
Provedor de dados: 31
Autores: Kaya,   Ozgur; Florkowski,   Wojciech J.; Suh,   Dong-Kyun.
The knowledge of the overall willingness-to-pay and the specific price premiums consumers accept when buying foods with less fat, saturated fat, sodium, sugar and more fiber shapes food manufacturer and distributor marketing strategies and supports the development of public health strategies. This study applies survey data collected in Korea to identify consumer profiles associated with the expressed willingness to pay a premium for foods with nutritionally desired attributes and, next, estimates the influence of consumer and household characteristics on the WTP a particular premium level for such foods. Results indicate the importance of socio-economic variables such as location, income and education, variables representing the risk of health problems...
Tipo: Conference Paper or Presentation
Palavras-chave: Willingness to pay; Price premium; Modified food; Republic of Korea; Survey data; Logit; Generalized ordered logit; Agricultural and Food Policy; Consumer/Household Economics; Food Consumption/Nutrition/Food Safety; Health Economics and Policy; Q1; C3; D1.
Ano: 2010
URL: http://purl.umn.edu/61004

Risk and De-Collectivisation: Evidence from the Czech Republic
Provedor de dados: 31
Autores: Bezemer,   Dirk J.
The replacement of wage-labour farms by family farms in Central and Eastern Europe during the transformation has been more limited than was initially expected. In this paper a formal framework is developed in order to analyse the behaviour of family farms and socialist-style farms in the presence of risk, given the typical post-socialist environment. Management incentives, ownership structure, lump-sum transfers and consumption choices are shown to have the potential to limit the size of family farms relative to socialist-style farms. The hypotheses are tested with survey data collected by the author in the Czech Republic.
Tipo: Conference Paper or Presentation
Palavras-chave: Transition; Agriculture; Structural change; Risk; Survey data; Risk and Uncertainty; D21; D81; O18; Q12.
Ano: 2002
URL: http://purl.umn.edu/24888

Economics of Fish Marketing in Central Uganda: A Preliminary Analysis
Provedor de dados: 31
Autores: Bukenya,   James O.; Hyuha,   Theodora; Twinamasiko,   Julius; Molnar,   Joseph J.
The paper examines profitability and market performance of small-scale fish traders selected randomly from a cross-section of nine fish markets in four districts in Central Uganda. Data were collected through a structured questionnaire which was designed to solicit information on traders’ socio-economic characteristics, marketing characteristics, operating costs and returns, and problems associated with fish marketing in the study area. Percentages were used to describe the socio-economic characteristics, market characteristic and problems associated with fish marketing while gross profit and marketing performance models were used to determine profitability, marketing margin and operational efficiency, respectively. The results suggest that fish trade is...
Tipo: Presentation
Palavras-chave: Fish marketing; Survey data; Gross profit; Market margin; Operational efficiency; Uganda; Agribusiness; International Development; International Relations/Trade; Marketing; Research Methods/ Statistical Methods.
Ano: 2012
URL: http://purl.umn.edu/119527

Economic Situation and Development Perspectives of Farms in Poland - An Analysis Based on Survey Data from Selected Polish Voivodships and a Comparison with German Farms
Provedor de dados: 31
Autores: Petrick,   Martin; Spychalski,   Grzegorz; Switlyk,   Michal; Tyran,   Ewa.
The aim of this paper is to present an analysis of farm-level data collected in a survey of 464 Polish farms in 2000. Performance indicators of farms in three Polish voivodships are compared with farm accountancy data from two German Länder. The results show that Polish farms are much less profitable than their German counterparts. The gap in income levels is much higher between persons employed in the agricultural sector than between average working persons in the two countries. Living standards of the Polish farm population in the north-west exceed those in the south-east of the country. The analysis suggests that the lower profitability of farms has two major reasons. First, farms in the German regions receive much higher levels of subsidies. Second,...
Tipo: Journal Article
Palavras-chave: Agriculture; Farm performance; Survey data; Poland; Germany; International Development.
Ano: 2002
URL: http://purl.umn.edu/98251

Input Subsidy Programs and Commercial Market Development: Modeling Fertilizer Use Decisions in a Two-Channel Marketing System
Provedor de dados: 31
Autores: Xu,   Zhiying; Jayne,   Thomas S.; Govereh,   Jones.
Replaced with revised version of paper 07/18/06.
Tipo: Conference Paper or Presentation
Palavras-chave: Crowding out effect; Input marketing channels; Fertilizer; Sub-Saharan Africa; Survey data; Marketing.
Ano: 2006
URL: http://purl.umn.edu/21270

POLAND'S AGRICULTURE: SERIOUS COMPETITOR OR EUROPE'S POORHOUSE? SURVEY RESULTS ON FARM PERFORMANCE IN SELECTED POLISH VOIVODSHIPS AND A COMPARISON WITH GERMAN FARMS
Provedor de dados: 31
Autores: Petrick,   Martin; Spychalski,   Grzegorz; Switlyk,   Michal; Tyran,   Ewa.
The aim of this paper is to present an analysis of farm-level data collected in a survey of 464 Polish farms in 2000. Performance indicators of farms in three Polish voivodships are compared with farm accountancy data from two German Länder. The results show that Polish farms were much less profitable than their German counterparts. The gap in income levels is much higher between persons employed in the agricultural sector than between average working persons in the two countries. Living standards within the Polish farm sector decline from the north-west to the south-east. The analysis suggests that the lower profitability of farms is a consequence of pronounced structural deficiencies due to a quite unfavourable workforce-land ratio on Polish farms and...
Tipo: Working or Discussion Paper
Palavras-chave: Agriculture; Farm performance; Survey data; Poland; Germany; Farm Management; Q12; C81; P32.
Ano: 2001
URL: http://purl.umn.edu/14894

CHINA'S DAIRY MARKET: CONSUMER DEMAND SURVEY AND SUPPLY CHARACTERISTICS
Provedor de dados: 31
Autores: Fuller,   Frank H.; Beghin,   John C.; Hu,   Dinghuan; Rozelle,   Scott.
This report documents data and other information gathered from a survey of urban households in Beijing, Shanghai, and Guangzhou, China. The survey was conducted as part of a research project aimed at understanding the evolution of dairy markets in Asia and the implications for dairy product trade. The survey data provide insights into the purchasing behavior and attitudes of urban consumers in China with respect to dairy products. The report describes the survey and collection process, summarizes selected data from the survey, and provides anecdotal information about the development of dairy production, processing, and product marketing in China.
Tipo: Working or Discussion Paper
Palavras-chave: China; Dairy products; Demand; Production; Supply chain; Survey data; Demand and Price Analysis; Livestock Production/Industries.
Ano: 2004
URL: http://purl.umn.edu/18680

Maize Yield Response to Fertilizer and Profitability of Fertilizer Use Among Small-Scale Maize Producers in Zambia
Provedor de dados: 31
Autores: Xu,   Zhiying; Govereh,   Jones; Black,   J. Roy; Jayne,   Thomas S.
Multi-year nationwide survey data is used to estimate maize yield response functions and determine profitability of fertilizer use by small-scale farmers in Zambia. There has been a dearth of empirical studies on economics of fertilization in the context of Sub-Saharan Africa. In this paper we identify major methodological issues arising from using survey data and estimate maize yield response functions for small-scale rural households that have various management practices and soil conditions in two major agro-climatic zones. Profitability of fertilizer use is determined for each group of households. Our findings provide the following key messages. First, households that obtained fertilizer on time and used animal draught power or mechanical power for...
Tipo: Conference Paper or Presentation
Palavras-chave: Maize; Yield; Fertilizer; Profitability; Survey data; Crop Production/Industries.
Ano: 2006
URL: http://purl.umn.edu/25730

URBAN DEMAND FOR DAIRY PRODUCTS IN CHINA: EVIDENCE FROM NEW SURVEY DATA
Provedor de dados: 31
Autores: Fuller,   Frank H.; Beghin,   John C.; Rozelle,   Scott.
In this paper we use 2001-2002 urban survey data we collected to analyze demographics, cultural factors, and purchasing behaviors influencing the consumption of fresh milk, yogurt, ice cream, and powered milk in urban areas of China. The data include frequency of consumption by product, location of consumption and purchase, exposure to advertising and foreign culture, and school milk programs. The variables serve as regressors in a double-hurdle model that examines the decision to consume or not to consume and the level of consumption. We also estimate consumption levels and participation equations with tobit and probit models.
Tipo: Working or Discussion Paper
Palavras-chave: China; Dairy products; Demand analysis; Limited dependent variable models; Survey data; Food Consumption/Nutrition/Food Safety; Livestock Production/Industries.
Ano: 2004
URL: http://purl.umn.edu/18564