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Book (series)Observations on the geometrical properties of accuracy growth in sampling with finite populations. 1999
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No results found.A common problem in sample-based surveys that are performed under operational constraints is how to scale data collection procedures so as to guarantee an acceptable level of sampling efficiency. This problem constitutes a frequent concern of fishery administrations with limited budget and human resources. Generally, lack of any a priori guidance on sample size requirements tends to increase the size and complexity of field operations and this, in turn, has a direct impact on the logistical aspe cts of data collection and data management procedures. The presented study attempts to provide some answers to the above problem and proposes a supplementary practical tool for use in the design of sample-based fishery surveys. Its major assumptions are that the target populations are finite and of known size and that progressively taken samples are random and independent of each other. Its main feature is the limited use of probabilistic approaches and the adoption of geometrical criteria and t echniques that would be described as "reasonably pessimistic". The method is based on a simple definition of a relative index of proximity of a sample mean to the population mean. This index has several geometrical properties that are only a function of the population size. Using these properties it is possible to formulate geometrical constraints that can be used for predicting a lower limit for accuracy at any sample size between 1 and the population size. -
Book (series)Sampled-based fishery surveys. A technical handbook 2002The purpose of this handbook is to summarize experience gained over recent years in fishery statistical development by the Fishery Information, Data and Statistics Unit (FIDI) of FAO, and provide planners and users of fishery surveys with simple and step-by-step guidance for developing and implementing cost-effective and sustainable fishery surveys. The methodological and operational concepts discussed here apply equally to both marine and inland capture fisheries and are presented in a manner t hat is generic enough to make them adaptable to most commonly used data collection systems. Statistical aspects are presented in a descriptive rather than theoretical manner. Emphasis is placed on the understanding and interpretation of the statistics and related indicators collected, rather than on the computations producing them. Readers interested in a more in-depth discussion on statistical and computing approaches may make use of the list of references that is given at the end of the handbo ok.
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Book (series)Manual on sample-based data collection for fisheries assessment. Examples from Viet Nam. 2000
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No results found.This manual deals with the practical implementation of a routine data collection programme. The data collection programme is developed through a top-down approach, from the identification of the objectives down to the practical recording and management of data obtained from the fishery. The issues are dealt with both through detailed discussion and by using simple examples. The examples are mostly based on situations in tropical fisheries, and in particular, experience has been drawn from develo ping a data collection programme in Viet Nam. The main questions addressed in the manual are which fisheries data to collect, where and when to collect them. Only data collected from commercial marine capture fisheries are considered (data from freshwater fisheries, cultured fish and experimental fishery are excluded). The methodologies used are mainly appropriate for a tropical, developing country, with many small (artisanal) vessels and a few large (industrial) vessels. The methodology is the “sample-based approach” - the manual does not deal with a methodology which assumes complete enumeration. The data collection methodology presented attempts to utilize whatever information can be obtained in practice in a developing country. Processing and storing of data (fisheries databases) and staff training are partly covered.
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