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

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

JOURNAL OF FISH BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

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

0022-1112

The dietand trophic level (TL) of the yellownose skate Zearaja chilensis in thesouth-western Atlantic Ocean (35∘ ?54∘ S), and how these varied in relation to bodysize, sex, maturity stage, depth and region were determined by analysis ofstomach contents. From 776 specimens analysed, 671 (86⋅5%) ranging from 180 to 1190mm total length (LT) had prey in their stomachs. The diet wasdominated by fishes, mainly the notothenioid Patagonotothen ramsayi and theArgentine hake Merluccius hubbsi. The consumption of fishes and crabs increasedwith increasing predator size, and these preys were more important in the norththan in the south. Isopods and other crustaceans were consumed more in thesouth and their consumption decreased as the size of Z. chilensis increased.The TL of Z. chilensis increased with LT from 4⋅29 to 4⋅59 (mean 4⋅53), confirming their ecological role as a top predator. The small and large size classesexhibited a low diet overlap and the highest spatial segregation, whereasmedium and large specimens had higher co-occurrence and dietary overlapindices. A clear distinction in tooth shape was noted between sexes in adultspecimens, with males having longer cusps. This sexual heterodonty may berelated to reproductive behaviour, increasing the grasping ability of malesduring courtship, because there were no differences in diet between thesexes.