Characterization of the infralittoral system along the north-east Spanish coast based on sport shore-based fishing tournament catches

Spatial and temporal variations in the structure of fish assemblages were analysed based on the catch data from a total of 2329 shore-based sport fishing tournaments held in north-eastern Spain from 2002 to 2006 with a view to characterizing the infralittoral system along 400 km of coastline and assessing the usefulness of these data as an additional means of monitoring coastal areas. A total of 63 species in 35 families were identified in the catches. Daily catch rates per fisherman varied from 0.1 kg to 0.5 kg according to the fishing area, and maximum catch rates and minimum species richness values were observed in the vicinity of the mouths of major rivers. Cluster analysis yielded six separate major groups. Two groups were characterized by predominantly or entirely rocky bottoms where the main species were Coris julis and Serranus cabrilla and were differentiated by a higher abundance of labrids and serranids and an absence of sparids. A third group encompassed areas under the influence of major rivers, where Chelon labrosus dominated the fish community. The other three groups were dominated by sparids but with differences in the total contribution by the main species, Sparus aurata, Lithognathus mormyrus, and Pagellus acarne, to each fish assemblage, indicating differences in ecological structure. The results suggest that sublittoral fish assemblages can be regarded as ecosystem descriptors and should not be overlooked as indicators of ecosystem changes. The study showed that a structured legislative framework for regulating recreational fishing tournaments can be extremely useful for monitoring littoral fishes at minimal added cost.