This background document provides a brief summary of some basic concepts underlying the
collection and use of fishing effort in resource assessment and management, and supplements the
review of these issues in GFCM Studies and Reviews No. 70 (Caddy 1998). Rather than repeat the
substantial body of information available in FAO reports, photocopied pages will be distributed
from various reports at the meeting, which provide easy access to standard forms for the collection
of effort and other related data.
The context is of course relative to the concept of Operational Units. Accadia and Franquesa (MS)
traced the development of the definition of an Operational Unit to the following final statement:
“For the sake of managing fishing effort within a Management Unit, an Operational Unit is the
group of fishing vessels practising the same type of fishing operation, targeting the same species or
group of species and having a similar economic structure. The grouping of fishing vessels may be
subject to change over time and depends on the management objectives to be reached”.
In general, if an OU is regarded as the only group of vessels fishing a particular resource wherever
it is located, the summarised effort data exerted, and the catch realized by this OU, can be used in a
standard production modelling approach. However, in the likely case that more than one OU, LOU
(Local Operational Unit based in a given port), or Fleet Segment, are fishing the same resource in a
Management Unit (Now referred to Geographical Sub-regional Area-GSA), then of course the issue
of standardisation and combination of the data generated by each OU must be resolved before an
effort-based resource assessment can be attempted. If the intent is to measure the economic
performance of a group of vessels fishing resources from different stocks in all areas within access
of the port (or on the high seas) the approach will have to be rather different, and perhaps the