Año 1997, Número 11 – 119-133

Año 1997, Número 11 – 119-133

García de la Rosa, S.B.; Sánchez, M.F.1997. Alimentación de Squalus acanthias y predación sobre Merluccius hubbsi en el Mar Argentino entre 34°47′-47°S.
Rev. Invest. Desarr. Pesq., 11: 119-133.
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The spiny dogfish, Squalus acanthias is an euribathyc, eurithermic and cosmopolitan species. In the Argentine Sea it consumes diversity of preys, characteristic of a generalist and oportunist feeder, but its principal food items are ctenophores, fishes and cephalopods. Diet overlap between sexes was found between 34°-37°S and 101-150 m, where males principally feed on fishes, squid and polichaetes, sharing only ctenophores and hake consumption with the females. Near 62 cm TL there is a shift in the diet, due to an increment of argentine hake Merluccius hubbsi and squid Illex argentinus predation and a diminution in ctenophores Pleurobrachia pileus eating.  Feeding shows an increment from north to south, its mode on 42°-43°S. Argentine hake is an important prey between 34°-35°S and 100-150 m deep and southern to 42°S, less than 80 m deep. No feeding differences were found during daylight hours for S. acanthias is a continuous feeder. This species nearly overlaps its distribution area with the one of argentine hake. Thereby, interespecific overlap and sharks predation pressure is almost permanent on juvenile and adult Merluccius hubbsi and it is higher southern to 44°S. Predation on 5-34 cm LT argentine hake occurs at 32-88 cm LT predator length, but the highest predation pressure is focalized on those smaller than 25 cm. There is a partial diet overlap between S. acanthias and M. hubbsi. This fact does not implie competence, for each species does not overlap principal food items.