Trophic ecology of yellownose skate Zearaja chilensis (Guichenot, 1848) (Elasmobranchii: Rajidae), a top predator in the southwestern Atlantic.

BELLEGGIA MAURO; CORTES F; BREMEC CLAUDIA; ANDRADA N. ; MASSA ANA; PAGLIERI S; FIGUEROA DANIEL E.

JOURNAL OF FISH BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 88 p. 1070 - 1087

0022-1112

The diet and trophic level (TL) of the yellownose skate Zearaja chilensis in the south-western AtlanticOcean (35∘ ?54∘ S), and how these varied in relation to body size, sex, maturity stage, depth andregion were determined by analysis of stomach contents. From 776 specimens analysed, 671 (86⋅5%)ranging from 180 to 1190mm total length (LT) had prey in their stomachs. The diet was dominated byfishes, mainly the notothenioid Patagonotothen ramsayi and the Argentine hake Merluccius hubbsi.The consumption of fishes and crabs increased with increasing predator size, and these preys weremore important in the north than in the south. Isopods and other crustaceans were consumed more inthe south and their consumption decreased as the size of Z. chilensis increased. The TL of Z. chilensisincreased with LT from 4⋅29 to 4⋅59 (mean 4⋅53), confirming their ecological role as a top predator. Thesmall and large size classes exhibited a low diet overlap and the highest spatial segregation, whereasmedium and large specimens had higher co-occurrence and dietary overlap indices. A clear distinctionin tooth shape was noted between sexes in adult specimens, with males having longer cusps. Thissexual heterodonty may be related to reproductive behaviour, increasing the grasping ability of malesduring courtship, because there were no differences in diet between the sexes.© 2016 The Fisheries Society of the British Isles