Time and spatial trends in landing per unit of effort as support to fisheries management in a multi-gear coastal fishery

Abstract

Landings by the multi-gear coastal fleet operating off the Portuguese continental coast include about 300 species, from which only a few are the object of management plans. In this study, daily landings (kg trip-1) are used, along with an effort indicator, vessel length overall (LoA), to obtain landings per unit of effort (LPUE) as a proxy for the species relative abundance, for a total of 48 species. LPUE indices were used as a response variable in linear models where year (2012-2016), season, region (north and south) and NAO index were explanatory variables. Seasonal and regional effects were found to significantly affect species abundance for a total of 41 and 40 species respectively, while year trends were found to be significant for 19 species, and the NAO index for 3 species. LPUE density maps are presented for several selected species and a subsample of trips, where VMS records were available. It is proposed that geographic and seasonal changes in LPUE can be used to understand trends in abundance and obtain information that can be used in support regional management plans.