LIMNETIC FEEDING IN Eleginops maclovinus (VALENCIENNES, 1830) IN THE VALDIVIA RIVER, CHILE

• Main Authors: Héctor Pavés, Germán Pequeño, Carlos Bertrán, Luis Vargas
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2002
• Subjects: included 114 individuals obtained using; Aconcagua; Antarctic; Argentina; Guzmán; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.382.957; http://www.ibcperu.org/doc/isis/1714.pdf

1830 is a monotypic species of the family Eleginopidae (Osteichthyes), suborder Notothenioidei. The species is thought to be of Antarctic evolutionary origin, and is one of the most eurythermic, euryhaline and stenobathic representative of the suborder (Pequeño, 1989). This species is endemic to southern Chile, southern Argentina and the Malvinas Islands, where it occurs near oceanic beaches, and in large and small estuaries. In Chile it is found south of the Aconcagua River (33ºS) and has been caught in rivers of southern Chile, several kilometers offshore of the river mouths (eg. Valdivia River, this study), and over 20km upstream in low salinity (limnetic) waters. Previous observations of the trophic relations of E. maclovinus had been made on specimens obtained in marine and estuarine habitats. Although this species has been generally considered as an omnivorous predator, the literature reflects two contrasting variations on this point, the first by Guzmán and Campodónico (1973) and Gosztonyi (1979), who postulated an ontogenetic change from carnivorous behavior in early juvenile stages to a herbivorous one in adults. The second opinion, held by Pequeño (1979) and Turner (1988) is that the species tended toward a carnivorous behavior throughout its entire ontogenetic development. In the present study the trophic relations between juveniles and adults of E. maclovinus within a limnetic habitat, namely the upper Valdivia River estuary, are compared. It was also tested whether E. maclovinus, the notothenioid species that most commonly inhabits fresh waters, preys upon typical freshwater species during its residence in this habitat, and remains carnivorous as observed in specimens studied from brackish and marine waters. Parasitological evidence obtained from the stomachs of the fish is also used to evaluate the hypothesis of carnivorous tendency in both juveniles and adults of this species.