Abstract

The food habits and trophic relationships of seven perciform fishes of the subtidal of the north of Chile: Acanthisthius pictus ('vieja colorada'), Paralabrax humeralis ('cabrilla espanola'), Hemilutjanus macropthalmus ('apanado'), Pinguipes chilensis ('rollizo'), Semicossyphus darwini ('pejeperro'), Anisotremus scapularis ('sargo') and Graus nigra ('mulata'), are analyzed in order to establish inter-annual changes of the diet of subtidal fishes of the north of Chile. Additionally, information about the diet of the omnivorous fish Medialuna ancietae ('acha'), is presented. The samples were collected with a spear gun during three national diving championships, that took place at the coast near Iquique (21°11'-20°20'S) during the autumn seasons of 1979, 1987 and 1996. The total number of prey items of each predator was valued by numerical and frequency of occurrence methods, and were later grouped in superior taxa and valued with the Shoener (trophic overlap) and the Shannon-Wiener index (trophic diversity). The results show preference for crustaceans (A. pictus), mollusks (A. scapularis), crustaceans-mollusks (S. darwini), crustaceans-fishes (H. macrophthalmus and P. humeralis) and crustaceans- mollusks - equinoderms (P. chilensis and G. nigra). The mean trophic diversity varied between 0.57 (A. scapularis) to 1.98 (G. nigra), with P. chilensis showing the highest index (2.61) at the 1979 period. The inter-specific and inter-annual low dietary overlap and its relationships with temporal changes in the feeding habits due to occurrence of 'El Nino' events in the north of Chile, is discussed.