A multivariate approach for defining fishing tactics from commercial catch and effort data

Fishing tactics correspond to fishing practices at the scale of the fishing operation. In the case of mixed fisheries, they are defined as a combination of target species, gear, and fishing location, at a given time of the year. This paper proposes an approach to determine fishing tactics from the analysis of commercial catch and effort data. The approach is based on typologies of fishing operations involving multivariate descriptive methods like factorial analyses and classification techniques. The obtained types of fishing operations are considered as fishing tactics. The approach is applied to two contrasting examples, a small-scale Senegalese fishery and a Celtic Sea fishery that operates at a larger scale. Catch per species and fishing effort are computed per tactic. Results emphasize the importance of fishing location and seasonal effects for characterizing fishing tactics.