Spatial and temporal trend in the abundance and distributions of gurnards (Pisces: Triglidae) in the North Mediterranean Sea.

In this study we investigated the spatio-temporal distribution of gurnards (8 species of Triglidae and 1 species of Peristediidae) in the North Mediterranean Sea using 22 years of MEDITS bottom trawl survey data (1994-2015). Gurnards showed significant differences in terms of abundance, dominance and composition among geographical sub-areas (GSAs) and ecoregions with the highest relative biomass (BI) found in GSAs under lower level of fishing effort on the continental shelf (i.e. Malta, East Corsica, Balearic Island, Eastern Ionian Sea). On the other hand, the lowest gurnards BI were observed in the highly exploited areas of Western Mediterranean and Adriatic Sea where the largest number of species with a negative linear trend in BI was also found. The temporal trends in species abundances highlighted a general decrease for the coastal species (C. lucerna, C. lastoviza, C. obscurus), as compared to the species inhabiting the deep continental shelf and slope (T. lyra, P. cataphractum). The results provided for the first time an overview of the spatio-temporal trend in the abundance of gurnards over the wide spatial scale of the North Mediterranean Sea indicating also the importance of this species guild for monitoring the impact of fishing pressure on demersal assemblages.