Distribution, growth, diet and foraging behaviour of the yellow‐fin notothen Patagonotothen guntheri (Norman) on the Shag Rocks shelf (Southern Ocean)

Abstract

The distribution, total length (LT) frequency and diet of Patagonotothen guntheri are described from 14 bottom trawl surveys conducted on the Shag Rocks and South Georgia shelves in the austral summers from 1986 to 2006. Patagonotothen guntheri (80–265 mm LT) were caught on the Shag Rocks shelf from depths of 111 to 470 m, but no specimens were caught on the South Georgia shelf. Multiple cohorts were present during each survey and LT‐frequency analysis of these cohorts suggests that growth was slow (von Bertalanffy K = 0·133). Evidence from stomach contents and acoustic data (2005 and 2006) showed that P. guntheri is primarily a pelagic feeder, migrating from the sea floor towards the surface to feed during daylight. The diet of smaller fish (<140 mm) was dominated by copepods, predominantly Rhincalanus gigas, whilst larger fish principally consumed the pelagic hyperiid amphipod, Themisto gaudichaudii and Antarctic krill Euphausia superba. Some larger fish also took benthic prey.