Spatial structures and temporal patterns of purse seine fishing effort in the NW Mediterranean Sea estimated using VMS data

Vessel monitoring systems (VMS) represent a tool that can provide information on the spatial and temporal distribution of fishing activity and a quantitative evaluation of the fishing effort at both spatial and temporal scales. The aim of this study was to characterise the spatio‐temporal structure of the Catalan purse seiner fishing effort directed towards anchovy or sardine, which was estimated by filtering VMS data (from 2012 to 2014) by species and seasons. The results showed that the mean location of the fishing effort directed towards anchovy did not vary among the summer seasons, in contrast to the efforts in spring and autumn, whereas the mean location of the effort directed towards sardine was constant over the seasons. The concentration curves indicated that similar fishing effort patterns occurred during all seasons when directed towards sardine, whereas the effort directed towards anchovy was more concentrated in summer. The ranges of the variograms indicated that the fishing effort directed towards both species formed patches. The dimensions of these patches changed from season to season, with the smallest magnitudes during the summer seasons. In this study, a seasonal distribution pattern of the fishing efforts was recognised that adequately captured the features of the distributions of small pelagic populations.