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Coordinating Working Party on Fishery Statistics (CWP)

Fishing effort

Fishing Effort is the amount of fishing gear of a specific type used on the fishing grounds over a given unit of time e.g. hours trawled per day, number of hooks set per day or number of hauls of a beach seine per day. The impact of an effort unit on the fish populations and the ecosystem in general differs with the vessel that deploy the gear and effort statistics need to qualified by vessel type and size/motor power. When two or more kinds of gear are used or when the same gear is used by different classes of vessels, the respective efforts must be adjusted to some common standard before being added. This standard is sometimes referred to as Effective fishing effort.

Three levels of precision of fishing effort are identified in reporting forms. Data should be provided for all three levels indicated as categories.

Category A refers to a detailed unit of measure, e.g. hours fished or number of sets, etc. These units of measure will vary with the gear used. For possible combinations of gear and effort see Annex N I.

Category B refers to "number of days fished", i.e., the number of days on which fishing took place. For those fisheries in which searching is a substantial part of the fishing operation, days in which searching but no fishing took place should be included in "days fished" data.

Category C refers to "number of days on ground" in addition to days fishing and searching also all other days while the vessel was on the ground should be indicated.

Information on the percentages of the catches that have been pro-rated is useful as per cent of pro-rated effort, not available when the data are 100 per cent recorded.

The effort may be nominal, reflecting the simple total of effort units exerted on a stock in a given time period. It may also be standard or effective when corrected to take account of differences in fishing power and efficiency and ensure direct proportionality with fishing mortality and this relates usually to a specific fishery and gear. If more than one gear is considered, standardization in relation to one of them is necessary. For biologists, a good measure of fishing effort should be proportional to fishing mortality. For economists it should be proportional to the cost of fishing.

Data on fishing effort are collected by means of the statistical questionnaire STATLANT B now limited to area 21, Northwest Atlantic.


FAO. Fisheries management. FAO Technical Guidelines for Responsible Fisheries. 1997, No. 4, 82 p.

Ricker, W.E. Computation and interpretation of biological statistics of fish populations. Bulletins of the Fisheries Research Board of Canada, 191:2-6.1975.