Diet of the smooth-hound, Mustelus mustelus (Chondrichthyes: Triakidae), in the eastern Adriatic Sea

The diet of the smooth-hound, Mustelus mustelus, in the eastern Adriatic Sea was investigated with respect to fish size and season. Stomach contents of 139 specimens, 67 to 137 cm in TL, collected by bottom-trawl from 2001 to 2003 were analyzed. Of the total number of stomachs examined, 24 were empty (17,2%). The prey items identified in stomachs belong to eight major groups: Cephalopoda, Polychaeta, Nemertina, Stomatopoda, Decapoda, Enteropneusta, Tunicata and Teleostei. Decapod crustaceans were the most abundant prey (%IRI = 63.1) especially for individuals up to 110 cm TL. Teleosts were second in importance (%IRI = 31.2), whereas other prey groups were of minor importance and were probably incidentally ingested food. At the species level, the decapods Atelecyclus rotundatus (%IRI = 6.7) and Munida rugosa (%IRI = 4.3) followed by the teleost Sardina pilchardus (%IRI = 2.7) were the most frequent prey. With M. mustelus growth, the proportion of decapods decreased whereas that of teleosts and cephalopods increased. Diet composition showed little seasonal variation; decapods were the most important prey taxon in all seasons, especially in summer. The results indicate that the smooth-hound feeds on a wide range of prey items and can be considered an opportunistic predator.Original Abstract: Alimentation de l'emissole lisse, Mustelus mustelus (Chondrichthyes: Triakidae), en mer Adriatique. Le regime alimentaire de l'emissole lisse, Mustelus mustelus, a ete etudie en fonction de la taille des poissons et de la saison. Les contenus stomacaux de 139 specimens, 67-137 cm TL, captures par chalutages entre 2001 et 2003, ont ete analyses. Sur l'ensemble des estomacs etudies, 24 etaient vides (17,2%). Le contenu stomacal de M. mustelus s'est avere compose de 8 groupes principaux de proies : cephalopodes, polychetes, nemertes, crustaces stomatopodes, crustaces decapodes, enteropneustes, tuniciers, et teleosteens. Les crustaces decapodes constituent les proies principales (%IRI = 63,1), ), surtout parmi les classes de taille inferieures a 110 cm LT. Les teleosteens sont des proies secondaires (%IRI = 31,2), alors que les autres groupes representent une nourriture occasionnelle. Au niveau specifique, les decapodes Atelecyclus rotundatus (%IRI = 6,7) et Munida rugosa (%IRI = 4,3) puis le teleosteen Sardina pilchardus (%IRI = 2,7) ont ete les plus frequents. La proportion de decapodes diminue avec la croissance, tandis que celle des teleosteens et des cephalopodes augment