Fuentes de datos  
  1. Information on capture production is collected annually from relevant national offices concerned with fishery statistics, by means of a system of standardized forms (see below), which list for each country the relative species items and fishing areas breakdown.
  2. In the case of some "aquatic products", data are also obtained from trade associations or other specialized international organizations to which data are also submitted. In this way the statistics are reviewed by subject matter specialists.
  3. Data concerning the nominal catch of certain major groups are generally reviewed in collaboration with the regional agency concerned. For example, for ISSCAAP group 36 (Tunas, bonitos and billfishes) data provided by the national correspondents are often replaced by the "best scientific estimates"produced by regional bodies collecting tuna catch statistics (i.e. ICCAT, IOTC, SPC and IATTC.)
Garantía de calidad  
The collection of capture statistics has been separated from aquaculture since 1996, for the period 1950-1995 capture and aquaculture were compiled together in the total production statistics.

Coverage completeness
Método de recolección: Data are collected by the following forms:

"FISHSTAT NS 1", this questionnaire is dispatched to countries on an annual basis, requesting information on nominal catch data for all commercial, industrial, subsistence, and recreational fishery operations in all inland and marine fishing areas. Where applicable, FISHSTAT NS 1 is supplemented by forms NS 6 for aquatic mammals, NS 7 for crocodiles, NS 8 for pearls, sponges and corals, NS 9 for aquatic plants.
"FISHSTAT NS 2" is intended for reporting data on capture production from inland waters. Those countries where the collection of statistics on inland fisheries is allocated to an administrative unit different from that in charge of marine fisheries are requested to fill in this questionnaire.
Método de elaboración: Where officially reported national statistics are lacking or are considered unreliable, FAO/FIPS makes estimates based on the best information available. Such data are flagged with an "F".When alternative sources of information are missing, the most recent officially reported data are repeated such data are flagged with an "R".
Mecanismo de validación: National statistics are validated through analysis, exchanges with Regional Bodies, discussions at working groups, comparative intelligence, expert advice, comparisons with trade, etc.

Coverage improvement
For major group 36 (tunas, bonito and billfishes), in order to improve coverage of world tuna catch statistics, national offices sources reported to FAO are confronted with statistics transmitted by regional bodies collecting tuna catch statistics.
Mecanismo de validación: There are three potential sources of tuna data discrepancies between records held by FAO/FIPS and regional bodies: 1) different sources; 2) different data coverage (e.g. exclusion of artisanal catches in the data collected by regional bodies; and 3) different dissemination timing.

Consistency and Accuracy
To facilitate the reporting of consistent and accurate world capture statistics, FAO/FIPS provides internationally agreed definitions for determining the nationality of the catch and the criteria for separating capture and aquaculture production.

The flag of the vessel performing the essential part of the operation catching the fish should be considered the paramount indication of the nationality assigned to the catch data. Aquatic organisms which are exploitable by the public as a common property resource, with or without appropriate licences, are the harvest of fisheries, while aquaculture production implies some form of intervention in the rearing process and individual or corporate ownership of the stock being cultivated.
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