Length composition, sex ratio, and pre-spawning migration of Dissostichus eleginoides in Subarea 48.3 during 1995

Document Number:

WG-FSA-95/27 Rev. 1

Author(s):

Agnew, D.J.

Agenda Item(s)

Abstract

Haul by haul Chilean and Argentinian data show that fishing forDissostichus eleginoides in 1994/95 took place in two major fishing grounds, West of Shag Rocks (Wshag) and North-West of South Georgia (NWSG). In March there was a high proportion of large females at Wshag (72%) but a nearly equal proportion of males and females at NWSG. It is suggested that a strong influx of small fish at Wshag in April reduced the mean length in the catch and increased CPUE (numbers of fish per hook), although sex ratio remained biassed in favour of females. Similar changes in mean length and CPUE were not seen at NWSG, although the sex ratio did change in favour of males (60% male by early May). The changes at Wshag are hypothesised to be the result of a prespawning migration of sub-adults, especially males, from shallow waters to deeper spawning grounds just prior to spawning in June-July