However, is often
probable that catches for newly reported species were earlier included under not identified (e.g. ‘Marine fishes nei’) or higher taxonomic level (e.g. genus, family, etc.) items, or even under another species, consequently decreasing the quantities reported onward for the more highly aggregated items. There are also cases in which countries have been reporting catch statistics with a good species breakdown for some years, thanks to specific projects or temporary availability of funds but, when the data collection activities ceased or became unsustainable, the information submitted was drastically reduced. Variations in the quality and level of species breakdown throughout the years make very buy Silmitasertib difficult to use the information in the database as an indicator of increasing or decreasing biodiversity in reported catches, as improvements in data reporting cannot be distinguished from BKM120 molecular weight real changes in catch composition. As soon as the annual deadline to submit data expires, FAO contacts the national correspondents of those countries that have not yet reported their fishery statistics. If after several reminders a country still does not return data FAO estimates the missing data and marks them in the database with an ‘F’. All data reported by countries are carefully checked and, when the figures are questionable, the
national correspondent is consulted for clarifications. Unfortunately, sometimes such requests remain unanswered and FAO has to take decisions whether including or not in the database data that
seems unreliable. There are countries which in some years are able to report only data Interleukin-3 receptor for a component of the fishery sector (e.g. industrial or artisanal) but FAO has to add up estimates for the missing catches because data on total fish supply by each country are needed to calculate the apparent consumption of fish and fishery products in the Food Balance Sheets . There are no predefined rules concerning how to produce the FAO estimates. In general, data from the previous year are either repeated or rounded to the nearest 10 or 100 to hint that they have not been officially submitted. When the total catch is available but species breakdown was not provided for a given year, catches by species are estimated proportionally to figures reported for previous years. In these cases, the ‘F’ is removed from the country’s totals in the relevant tables of the FAO capture production yearbook. The attribution or removal of the ‘F’ to totals is very accurate for recent years but may not be always consistent for older years. Data reported for the latest year are considered as provisional and may be subject to revision the following year. In addition, FAO revises catch data for backward years as new data provided by national correspondents, RFBs or other sources become available. Among the most significant data revisions occurred in the last twenty years, two concerned China’s statistics.