The Handbook on the Collection of Fisheries Statistics for Inland and Coastal Fisheries has been prepared by the Secretariat of the Southeast Asian Fisheries Development Center (SEAFDEC). Handbook on Collection of Fisheries Statistics for Inland and Coastal Fisheries, Southeast Asian Fisheries Development Center.
Introduction 1 Scope of this document
Rationale for the Handbook
If some of the information is already available, it is spread across many different sources scattered in time, not providing enough focus to be practically useful in the Southeast Asian context. While this may be appropriate for some sectors of the fisheries, the small-scale and fragmented nature of much of the inland and coastal fisheries requires some alternative approaches.
Scope of the fishing operations
In contrast, the commercial fishing in inland fisheries consists mainly of small-scale one-man fishing, moreover, the catch from this commercial sector is only a small part of the total fishery production. Therefore, some of the variables routinely collected for coastal fisheries (eg, the length composition of the catch) may not be particularly useful for most inland fisheries.
Fishery Statistics 1 Introduction
Fisheries Management: considerations and practical approaches
In addition, overfishing is not the greatest delicacy for the sustainable use of fishing resources. The only viable management method is to transfer ownership of resources to resource users and allow them to manage them themselves.
Fishery Statistical Variables
Alternatively, the value of the fisheries sector can be expressed in the jobs or livelihoods provided. It is essential to be aware of the existing subsidies to enable policy and planning for the sector.
Basic Statistical Theory
The nature of the standard deviation allows us to make predictions about what percentage of the data is between certain limits. To make it even clearer, a measure of the reliability of the mean estimate can be added.
Census and Sampling Approaches 1 Introduction
Sampling
A useful concept in statistics and one essential to the concept of sampling is that of the normal distribution. The position of the normal distribution curve along the x-axis depends on the value for the mean.
Sample size
Using any of the above formulas will usually give a conservative estimate of the number of samples to take. Once the sample size is determined, the logistics of the survey must be decided upon.
Statistical System Design
General approach
After the objectives for the data collection have been determined then comes the difficult choice of which parameters to collect in order to achieve the objectives of the data collection system. Fisheries line agencies do not operate in a vacuum and often other departments are involved in the collection of fisheries statistics at various levels.
Planning and preparatory work
It is also important to analyze the results of the survey as quickly as possible. This is the most important stage of the statistical system and a test for the appropriateness of the data collected.
Recommendations for a minimum statistical system
Catch assessment should be carried out separately for different sub-sectors of the fishery, which can be distinguished by gear or operations. Effort estimates should only be collected for those fisheries that can be managed based on gear and effort limitations. It is crucial that effects of these three can be measured (unless this is not desirable due to lack of effect).
At a general level, agreement has been reached on the use of a combination of catch and effort sampling for those sectors of the fishery that can be managed through gear and effort limitations (reservoir and lake fisheries and the larger commercial fisheries).
General description of collection methodologies
Introduction
Data Collection Methods .1 Register
As data contained in the register must be regularly updated and checked, registers tend to be limited to the large-scale sectors of the fishery. The purpose of the questionnaire and the questionnaire were explained in detail in the meeting. Introduce each section of the survey by explaining what it is about - Make the questions clear and simple;.
Sometimes it is possible to calculate in advance the number of interviews per village or stratum, based on the required reliability and the (expected) variability of the information.
Catch Assessment Surveys
Sample surveys for catch and effort at landing sites
However, the official register can provide the basis for planning the framework survey. Local fisheries officers should be appointed full-time for the collection of frame survey data. Information on when to expect seasonal changes in the type of gear used can be derived from the frame survey and the empirical knowledge of the data collectors.
It is sufficient to measure only one sample of the total catch for one type of boat gear.
Using Logbooks for Catch Assessment .1 Introduction
The required number of participating fishermen can be calculated based on the variation in catches and the required reliability of the resulting estimates (see section 4.3). The need for speed in making estimates is particularly urgent to provide feedback to participating fishermen and to. Monthly results must be returned to participating fishermen in the form of a one-page summary report for each month.
If, on the other hand, the selected unit is the fisherman, the average for all participating fishermen in each stratum is calculated and then increased to the total number of fishermen in each stratum.
Catch Assessment by means of Interviews .1 Introduction
The scope of the survey is similar and even similar log sheets may be used. Since the interview and diary method are essentially the same as those discussed in section 7.2 and 7.3, the same diary sheets and survey forms can be used (Appendix IV and V). The total extrapolated catches for each household member can be combined into a household figure.
This estimate can easily be scaled up to obtain an estimate for the total production for each stratum.
Economic Surveys
Fish Price Surveys
Judgment sampling is more practical in the day-to-day operation of price collection, where items and respondents must be changed regularly. Note that it is necessary to obtain an estimate of the average price in order to be able to monitor price fluctuations and to be able to calculate margins (profits). Some knowledge of the marketing process, trade flows and key products is required to select respondents and subjects to monitor.
If possible, prices should be collected by questionnaire; it is still necessary to take some samples to regularly check the returned data.
Employment
In many cases, it turns out that fish prices form clusters, where certain species are almost always sold at the same prices. In those cases, it is possible to reduce the frequency or number of categories (species/quality classes) for which prices are recorded. Unless the year the business started is not included in the register, it is not necessary to ask for this.
It is not possible to visit all the companies in person to explain the questionnaire and the objective of the survey, so this should be explained on the questionnaire.
Trade patterns
Identification of the importance of the main components of the social structure of the fishing trade network. The research should also try to find out the type of hubs and what percentage of the business is fish related. Some shipping companies will only specialize in fish for part of the year, as the supply of fish is extremely seasonal, especially in inland areas, and is closely related to the flood season.
Once the spatial structure of the marketing system is established, the next step is to quantify the volumes of fish and fish products, their origin and destination.
Livelihood Data
Fish Consumption surveys
Logbooks make it possible to map fish consumption over a longer period, from a month to an entire year. The sample size can be determined based on the size of the total population and the variation in average fish consumption. An estimate of the amount of 'import' and 'export' of fish and fish products from the study area is useful to calculate the sample of fish production, but is not essential if source (caught, purchased, donated or farmed) information is obtained . ;.
However, the sampling approach may be different; it depends on the exact objectives of the study.
Involvement in Fishery Activities
Alternatively, the number of days a particular activity is undertaken per month or the percentage of time spent can be used if engagement between activities needs to be compared. This can be used as an aid in describing the requested information to the interviewees. These average engagement levels can be used to indicate the different levels of engagement between activities within each group.
The variation that can be calculated for the sample is assumed to be representative of the variation of the entire population (i.e. the socio-cultural group).
Non-Routine data collection
- Ad-hoc surveys
- Non-routine surveys
- Structural Fisheries Data
- Data collection in a co-management setting
- Data Validation and Verification
- Data processing
- GIS as a tool for Stratification and Analysis
An important component of the data verification is obtaining feedback from collectors and fishermen on the information provided. Checking the data entry can be done by double punching or taking random samples of survey forms, log sheets or questionnaires that are checked in full. A simple way to implement this is to translate a separate set of the data entry interface forms.
Often this is not simply due to the design of the data entry screens, but more often a combination of factors.
TRAINING
Part of the basis for fisheries statistical training is provided by the current document, with the addition of local examples and case studies for each training location. Staff are trained in database design and programming, the approach and software used must be standard for all participating countries and compatible; The first half of this handbook has emphasized that the main focus of any statistical system should be an in-depth assessment of its objectives, data requirements and methodology.
In many cases, it is not a lack of understanding of how to do this, but an unsystematic approach to the entire statistical system.
GLOSSARY
Boat Activity Coefficient (BAC) The percentage of fishing units expected to be fishing during any given day of the survey period. Fishing mortality A mathematical expression of the rate of death in a fish stock caused by fishing. Nominal catch The amount of catches that are landed (expressed as live weight equivalent).
Round weight The weight of the whole fish before processing or removing any part.
- frame survey data Annex 2 catches and landings
- log sheet migration monitoring Annex 5 Catch assessment logbook sheet
- employment questionnaire (for wage labour with companies etc) Annex 7 marketing log sheets (series of formats for marketing studies)
- Fishery activities form (individual interview survey)
In: New approaches to improve inland fishery statistics in the Mekong Basin. 34; Nonhuman/Nonhuman/Human: Actor-Network Theory and the Possibilities for a Nondualistic and Symmetrical Perspective on Nature and Society." Included in the following pages are several examples of survey forms taken from a number of surveys conducted in Southeast Asia or adapted from many sources.
The survey formats are mainly based on the work by the Mekong River Commission's Fisheries Program with riparian agencies in the Mekong River Basin.
Frame survey form
Catches and landings
Collection of effort
Migration monitoring log sheet
Daily Fish Catch Logbook4
Employment Questionnaire
Do traders always sit in the same market position or do they move from day to day? If you buy your fish locally, from which if you next buy fish. If you buy your fish from other areas, from which if you subsequently buy fish.
Quality of fish: freshness, color of meat ____ Quantity or scarcity of fish available ____ Price determined by the people you buy from ____Price of fish determined by the customer.
Consumption Interview Survey Form
Fishery activities form
