Diet of Scorpaena porcus and Scorpaena notata (Pisces : Scorpaenidae) in the Western Mediterranean

Food preferences of 230 Scorpaena porcus and 576 S. notata were investigate d from the stomach contents of fish caught in the Gulf of Valencia (Spain), between October 1991 and October 1994. Our aim was to study the effects of predator size and season on the feeding habits of both species, the existe nce of a possible dietary overlap between species, and to compare our resul ts with those of other studies in the Mediterranean. Crustacea Decapoda con stituted the preferential prey of both fish species, whereas Amphipoda were secondary prey. However, these two scorpaenids had different diets, shown by the prey species composition of the stomach contents. Scorpaena notata h ad a more diverse diet (67 different species) than S. porcus (44 different species). The vacuity index was low for both species, although it varied si gnificantly over the year, with a maximum during the reproductive period. L ittle variation was found in the food composition of different S. porcus si ze groups: brachyura dominated in number and occurrence in the diet of all size classes. A variation was found in the food composition of different S. notata size groups: the frequency of occurrence of reptantia and brachyura increased with increasing S. notata size, whereas the frequency of amphipo ds, mysids, isopods, and copepods decreased. In both species, seasonal diet ary changes were also recorded. There was a moderate dietary overlap betwee n these two species.