Contribution of polychaetous annelids to the diet of Cheilodactylus bergi (Pisces, Cheilodactylidae) in Argentina

The hawkfish (castaneta) Cheilodactylus bergi Norman, 1937 is distributed i n the Atlantic Ocean, from southern Brazil (22 degreesS) to the Gulf of San Jorge in Argentina (47 degreesS), between 50 and 150 m depth, and constitu tes a fishing resource of commercial value. Previous studies indicated that polychaetes constitute its main food. The contribution of different famili es of worms to the diet of hawkfish and the relationships between those tax a and the benthic fauna of the feeding grounds are presented in this paper. A total of 522 specimens of fish was measured, weighed and the gut content s analyzed. Polychaete families, mainly Onuphidae, Lumbrineridae and Eunici dae, were the most important feeding items in specimens from 28 to 51 cm to tal length, both in percent of frequence (%F) and percent of weight (%W). O ccasional presence of Aphroditidae, Arabellidae, Palmyridae, Lysaretidae an d Dorvilleidae was recorded. Bibliographic data on faunistic composition of feeding grounds indicate that polychaetes constitute between 12 to 21% of number of taxa of macroinvertebrates. C, bergi feed upon 25-38% of species of polychaetes present in the area. It is concluded that C, bergi feed on p olychaetes which are mandibulated, implying mobility over the benthic surfa ce.