THE PARASITE FAUNA AND MORPHOMETRY OF THE SOUTHERN HAKE MERLUCCIUS AUSTRALIS (HUTTON) AS INDICATORS OF STOCK UNITS

Abstract

The parasite fauna and morphometry of the Southern hake Merluccius australis (Hutton) was examined in 685 fishes collected between 1992 and 1993 from inshore and offshore fishing areas along the Southern coast off Chile in the Pacific Ocean, (between 44°S and 56°S) up to the viánity of the Malvinas islands, in the South Atlantic Ocean. Twenty- three morphometric variables were recorded in each fish and 15,339 parasites belonging to 15 taxa were collected. The data were analyzed with uni- and multivariate statistical techniques. There were high similarities in parasite fauna and morphometry between fishing areas, but there were also small although significant differences that suggested migratory patterns and ontogenetic variations in feeding habits of hake as well as on the ecological conditions that surround them as they got older. These differences were due mainly to the different age composition of hakes between the fishing areas as well as to the differences in the prevalence or abundance of Elytrophalloides oatesi, Derogenes varicus, Grillotia heptanchi, Hysterothylacium sp., Clestobothrium crassiceps, Contracaecum sp. and Hepatoxylon trichiuri. It is concluded that there is only one puré stock and at least four ecological stocks in the study area.