versión On-line ISSN 0717-6538
MURILLO, Carlos; OYARZUN, Ciro y FERNANDEZ, Italo. LATITUDINAL AND TEMPORAL VARIATION IN THE DIET OF DISSOSTICHUS ELEGINOIDES SMITT, 1898 (PERCIFORMES: NOTOTHENIIDAE) IN DEEP ENVIRONMENTS OF THE SOUTH AND CENTER COAST OF CHILE. Gayana (Concepc.) [online]. 2008, vol.72, n.1, pp. 94-101. ISSN 0717-6538. doi: 10.4067/S0717-65382008000100011.
The diet of Dissostichus eleginoides, in three areas of the center-south coast of Chile, between 36° and 51°S was studied. The analysis of 1583 stomachs, of which 12,8% presented remains, shows a trophic assemblage with 22 families and 26 species. According to the IIR, the bony fish remains constitute 95,6% of the diet, being Macrouridae and Ophidiidae the most important families, representing 21,1% and 11,2% of the IIR respectively with less importance cephalopods and occasionally Anthozoa and Polychaeta also appear. Intraspecific variation in the diet, associated with sex or the size of the individuals was not observed. Significative geographic differences among the diets were observed specially in fish from the most austral area, respect to the fish captured in the most northern areas, whereas the composition of its diet is similar. The previous finding is explained by the high consumption of Onychoteuthidae cephalopods in the most austral zone and the null depredation on this item by the northern fish. Seasonal variation in the diet is demonstrated for all studied areas, in Spring-Summer the Patagonian toothfish fed mainly on ophidiid fishes, whereas at the time of Autumn-Winter, increases the participation of cephalopods and rattail fish in its diet, becoming this one the main prey. Also in Autumn-Winter, it is increased the contribution in specimens number, frequency and number of species of cephalopods in the diet of D. eleginoides in all areas and specially in the southern most area where the family Onychoteuthidae duplicates its representation, reaching more than 8% IIR. According to the H' and J' indices, the species displays a narrow trophic heterogeneity, corresponding to a stenophagic species (H'= 0,50), which is associated to a low uniformity (J'= 0,39), behaving like a secondary and/or tertiary carnivore, that predates mainly on demersal fish like Gadiformes and Ophidiiformes, in addition to mesopelagic teutid cephalopods, reaching the last special group importance in the South zone of Chile.
Palabras clave : Patagonian Toothfish; trophic ecology; deep sea; continental slope; Chile.