Coordinating Working Party on Fishery Statistics (CWP)

Date and time

Time units

The calendar year (Gregorian calendar, ISO 8601), i.e. the period between 1 January and 31 December, is the annual time unit normally used in fishery statistics.

For certain specific purposes (e.g. Antarctic fisheries, fiscal purposes) it may be deemed more appropriate to use a different 12-month period which may be referred to as a split year. Such situations arise when the sector under consideration exhibits appreciable activity over the end of the calendar year. The end points of a split year may be selected as desired but should be preferably at a time when activity in the sector is reduced. Examples of split years in use by various fishery authorities include 1 July - 30 June (of the following year), 1 October – 30 September and 1 December – 30 November.

In tabulations where space restricts the labeling of a split year to a single year or where data for calendar and split years are tabulated together, the practice is for the split year to be represented by the calendar year in which the split year ends. Thus a split year recorded in a statistical bulletin as 2002 refers to the split year 2001-2002.

Attention is drawn to the apparent anomalies that may be observed when comparing data from two sectors of fishery statistics. For example, in highly seasonal fisheries occurring at the end of the time period, recorded data on catches may not be matched by corresponding data on landings. This is explained by the catches being made in one time period, and the landings in the following one. Similar situations can arise with fishery commodities production and trade data.

Date time standard

For compatibility of national and regional fishery statistics, it is recommended that date and time be recorded in ISO 8601 format using the Gregorian calendar and 24-hour time keeping system. The general format is to record date as YYYY-MM-DD (or YYYYMMDD), time as hh:mm:ss (or hhmmss), and date time as YYYY-MM-DDThh:mm:ss (or YYYYMMDDThhmmss); seconds may be provided optionally. The recorded date and time should represent the date and time of a measurement, observation or event, or the date and time when data were obtained by a vessel's navigation equipment or other electronic device, and all dates and times reported in logbooks and fishery statistics should be referenced to Coordinated Universal Time (UTC). In cases where dates and times are reported in local time, then the UTC offset (±hh or ±hh:mm) at the location should also be reported. For example:

UTC date and time      2008-10-31T15:07Z (where Z denotes a zero UTC offset) or
local date and time      2008-10-31T17:07+02 (where +02 denotes a UTC offset of +2 hours).

Note that to calculate UTC date and time one has to subtract the offset from the local date and time.

Resources for date and time

International Organization for Standardization (ISO). 2017. ISO 8601 Date and time format. [Cited 1 November 2020].