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Diet composition of smooth-hound, Mustelus mustelus (Linnaeus, 1758), in Aegean Sea, Turkey

2009; Volume: 139; Issue: 1 Linguagem: Inglês

2295-0451

Halit Filiz,

Identification and Quantification in Food

Elasmobranch fishes are among the top predators in the marine environment and thus play an important role in marine ecosystems, potentially regulating, through predation, the size and dynamics of their prey populations (1; 2). Since elasmobranchs are frequently apex predators in marine ecosystems, information on the composition of their diet is essential for understanding trophic relationships in these systems (1). Sharks are often typified as opportunistic predators, with a wide trophic spectrum that ranges from plankton to marine mammals. In general, oceanic elasmobranch species feed on squid and big fishes (3), whereas the coastal and benthic species feed on crustaceans, molluscs and small or juvenile fishes (4 ; 5 ; 6). A few species feed on other elasmobranchs, birds, reptiles or marine mammals (7; 8 ; 9). Ontogenetic variation in diet is well known (10; 11), with a strong tendency to ingest larger and more mobile animals with increasing size. However, it is noteworthy that, while all sharks are higher-level predators they are not all true apex predators (12). Demersal sharks occupy open habitats, including sandy, as well as more complex, closed habitats such as rocky areas and coral reefs (12). Those sharks living on or near the seafloor generally have ventral mouths containing relatively small teeth as is the case in Mustelus mustelus. Members of the Mustelus genus (Chondrichthyes, Triakidae) are common throughout the Mediterranean (except for the Black Sea) and the eastern Atlantic (13). The smooth-hound, M. mustelus (Linneaus, 1758), is a small, bottom-living shark, which occurs at depths between 3 and 150m (14). The species is common in the northeast Atlantic and in the Mediterranean (14; 15). Although there is no directed fishery for smooth-hound, it is captured as by-catch in the trawls in Sigacik Bay and landed. Published information about feeding of this species is limited despite its abundance. Data on trophic ecology only mention that they feed mainly on crustaceans, but also cephalopods and bony fishes (15). SAUER & SMALE (16) provided some data on diet composition in the Atlantic, and MORTE et al. (17) quantified the diet in the Gulf of Valencia (Mediterranean). CONSTANTINI et al. (18) gave information about feeding habits in the northern Adriatic Sea (Mediterranean). However, similar studies from Turkey’s coasts are scarce. The only information about feeding in this species comes from KABASAKAL (19) for the Aegean Sea. Yet, such information is necessary to understand the role that this species plays in the trophic structure of coastal marine communities in this area (20). To resolve this, this study presents data on the feeding activity of smooth-hound from the Aegean Sea.