Peces mesopelágicos frente a la costa norte de Chile (18°25'-21°47'S)

Abstract

Mesopelagic fishes captured in the deep scattering layer (DSL) off the I Region of Chile, in 5 transects between 18°25' and 21°47'S, from 10 to 100 miles offshore, were studied. A 9.16 m2 mouth IKMT net was used. The DSL was registered with a SIMRAD ecosounder at frecuencies of 32 Khz and jointly the oceanographic conditions at each station were recorded. In 23 sampling stations 20 families and 39 species of fishes were detected. Most abundant families were Myctophidae and Gonostomatidae, the former with 22% of total fish biomass and the latter 67% of total captured specimens. 62% of the identified species were temperate water elements (tropical andlor subtropical) and 7,7% cold water species (antarctic andl or subantarctic), showing that the community structure is transitional between tropical and subantartic communities. The Shannon-Wiener index (diversity) and Winer index (similarity) showed the existence of four discrete groups of stations, determined by the oceanographic conditions and water masses. The DSL showed an upper limit at 250m during the day and the separation of a layer that ascended to the surface during the night.