Selectividad por tamaño de las presas en merluza común (Merluccius gayi gayi), zona centro-sur de Chile (1992-1997)

Abstract

Size-based prey selectivity in Chilean hake (Merluccius gayi gayi) is analyzed using a data base of stomach contents collected from 1992 to 1997. The Ursin prey selectivity index and the size-based selectivity coefficients were calculated by age for the Chilean hake (cannibalism); the galatheids squat lobster (Pleuroncodes monodon) and yellow squat lobster (Cervimunida johni); the clupeiforms common sardine (Strangomera bentincki) and anchovy (Engraulis ringens); and other combined prey. Hake are confirmed to consume larger prey as they grow and individuals over two years of age show a preference for the young fraction of the hake population (0-4 years; cannibalism), anchovy (0-1 year), and lobster (0-1 year). Hake over four years of age also prefer squat lobster and yellow squat lobster (> 2 years). High selection coefficients are found for the remaining prey, mostly zooplankton (euphausids) and myctophids, with predators from 0 to 4 years. The selection coefficients calculated herein constitute a quantitative basis for improving multispecific evaluation models that allow the quantification of the trophic impact of Chilean hake on commercially important species of the benthic-demersal and pelagic system off central-southern Chile.