Biology and distribution of South Georgia icefish (Pseudochaenichthys georgianus) around South Georgia and Shag Rocks

Abstract

Pseudochaenichthys georgianus is a member of the unique Channichthyidae family of fishes, which lack haemoglobin. The distribution, length-frequency and summer diet are described from 14 bottom trawl surveys undertaken in the summers between 1986 and 2006. Pseudochaenichthys georgianus (50 -590 mm TL) were caught throughout the South Georgia shelf from depths of 76 -370 m, but very few specimens (, 1%) were caught on the Shag Rocks shelf. Multiple cohorts were present during each survey and length-frequency analysis of these cohorts suggests that growth is fast during the first 3 -4 years. Stomach contents analysis (2005 & 2006) indicated that P. georgianus is a pelagic or semi pelagic predator, with the summer diet dominated by Antarctic krill (Euphausia superba). Fish (channichthyids and notothenids) were also taken, but were a relatively minor part of the diet.

Economic Competition for High Profits from Antarctic Living Resources in Their Protection Area

“…For example, large catch in that period was 4. highest fish concentration) [6,10]. They have not any information about the other regions of shelf and about young fish (Fig.…”

“…They have not any information about the other regions of shelf and about young fish (Fig. 17), that were numerous on different sides of island because of its migrations [10,11,15]. Juvenile (1 age group, 19-24 cm) recruit to the south of the island before migrating to the northern shelf [10].…”

“…17), that were numerous on different sides of island because of its migrations [10,11,15]. Juvenile (1 age group, 19-24 cm) recruit to the south of the island before migrating to the northern shelf [10]. The majority of that juvenile fish were recorded from the south-west of South Georgia Island, possible a nursery ground [10].…”

“…To exact estimate the biomass of fish, research cruises were arranged every year sampled all Antarctic ocean divided into grid statistical squares at three depth strata (< 150 m, 151-250 m and > 250 m) in regard to study fish stock and biomass [10]. Data of biomasses estimated from that cruises with swept area were approximated by time series equations (Figs.…”

“…Due to the tactics of the commercial vessel to maintain highest catch, they were removed in fishing season from November-February, from concentrations on spawning ground in north-east of the island "higher numbers of stage 3 fish were caught to the east", "larger and older fish migrating to the northern shelf" (Figs. 17, 25 and 26) [6,10]. Reports indicate that most spawning occurs northeast, which is close to the shelf shore waters [44].…”