In fisheries and conservation biology, the catch per unit effort (CPUE) is an indirect measure of the abundance of a target species.
Changes in the catch per unit effort are inferred to signify changes to the target species' true abundance.
The data are also easy to analyse, even for non-specialists, in contrast to methods based on transects.
[3] The main difficulty when using measures of CPUE is to define the unit of effort.
[4] CPUE is also often nonlinearly related to abundance, making interpretation more difficult.