7. ACTIVE DAYS SURVEYS

7.1 OBJECTIVE
7.2 DATA RECORDING

7.1 OBJECTIVE

Active Days Surveys are usually carried out at the end of the month, when all sampling has finished and estimates are about to be produced. Its objective is to determine a time raising factor for estimating total fishing effort.

7.2 DATA RECORDING

The following theoretical example illustrates a simple way of recording Active Days for each estimation context (minor stratum, month and boat/gear type) through discussions with fishers at the end of each month, since Active Days do not remain constant over time.

In the example there are two minor strata (SW Coast and NE Coast) and five boat/gear types, comprising gillnets, beach seine, hook and line, traps and shrimp trawlers. Each combination of minor stratum - boat/gear type requires an indication as to the number of active days to be used as time raising factor for the given survey period.

Estimation of fishing effort for June 2001 - Active Days
Minor stratum	Boat/gear type	Active Days	Remarks
SW Coast	Gillnets	24	2 days of bad weather No fishing during 4 Sundays
	Beach seine	26	No fishing during 4 Sundays
	Hook and line	26	No fishing during 4 Sundays
	Traps	29	2 half-days of bad weather
	Shrimp trawlers	-	No such boats in stratum
NE Coast	Gillnets	26	No fishing during 4 Sundays
	Beach seine	30	All days potentially active
	Hook and line	-	No such boats in stratum
	Traps	-	No such boats in stratum
	Shrimp trawlers	30	All days potentially active

To be noted that:

• Each raising factor is determined by removing the number of days with uniform inactivity from the number of calendar days (in this case 30 for June),
• Active Days are boat/gear-specific and area-specific. Events affecting a stratum or a boat/gear category may not be affecting others.
• Days of non-activity should not be confused with individual boat activities that are the object of BAC (see section 9). For instance, if it is known that, on average, boats with traps do not operate more than 15 days in a month, this does not imply that the raising factor should be 15, else fishing effort for that boat/gear would be grossly underestimated.

It is possible that an event will affect only part of a fishery. For instance, bad weather may only affect half of the boats of a certain category. For the boats with traps in SW Coast bad weather affected only half of them, meaning that only one day (or two half days) were subtracted from 30. Such refinements are of course useful but not always feasible.

SUMMARY In this section supplementary guidelines regarding the use of time raising factors known as Active Days were considered, noting that: Active Days are very important and greatly affect the estimation of total fishing effort. Active Days express, in a uniform manner, periods during which fishing activities can potentially occur. In contrast to Boat Activity Surveys, they do not account for trip variability of individual boats. Active Days are area- and boat/gear-specific. Active Days can simply be set to the number of calendar days in a month when sampling in time is frequent enough to cover both normal and exceptional (low or zero activity) events.