CCAMLR

This manual provides the documentation required for running the spatially-explicit population simulation software, Fish Heaven, which is available through the secretariat as well as the AAD.

This manual provides the documentation required for running the Generalised Yield Model (GYM) and its graphics user interface, which is available through the secretariat as well as the AAD.

This manual provides the documentation required for running the mixture program, CMIX, and its user interface through an Excel spreadsheet Add-In. This software is available through the secretariat as well as the AAD.

Thirty nine Dissostichus eleginoides were released in the vicinity of Heard Island carrying archival tags in April 2002. Since then seven have been recaptured and the depth and temperature data they recorded is analysed here. Most of the fish had periods of active vertical movement alternating with periods of relative inactivity, loosely correlated with moon phase. The direction of vertical movement was influenced by the bottom topography, with fish on the relatively shallow plateau or in the bottom of a valley only moving upwards from their resting depth, while those on the intervening escarpment moved both upwards and downwards. Major vertical movements took place between 0500 and 1100 local time.

In 2001/2002 Russian and UK vessels undertook surveys for icefish at South Georgia. Both used acoustic and trawl methods, and this paper uses both datasets to explore the similarities and differences between the surveys and discuss how much of the variation between the vessels was due to differences in the gear used and how much was due to natural spatial/temporal variability of the stock.
The acoustic surveys indicated that icefish were not only located near to the seabed, but that a significant portion of icefish biomass was located in the water column. Thus the traditional approach of using bottom trawls to assess icefish standing stock has resulted in biased estimates below the true value: acoustic estimates are ~ 1.5 times greater This should be taken into account in the forthcoming stock assessment during WG-FSA–2002.
These results show that the current observation system for the collection of data for icefish stock assessment should be changed to include regular acoustic surveys. This will improve the stock estimates of this species, and to achieve this we recommend the development of new survey designs and corresponding manuals.

The total capture of rays in the Subarea 48.3 longline fishery is composed both of rays brought on board and a number that are knocked off the line or fall off before they reach the deck. We estimated total capture (ray numbers) for some of vessels fishing in Subarea 48.3 in 2001 by utilising new information collected by observers on the rays appearing during their tally period. This estimate is entirely independent of vessel records of landed and discarded rays. For the one vessel that we have good species composition and mean weight data we have extended the number estimate to give capture weight by species.

We describe a previously unknown Amblyraja, A..sp.anon, from South Georgia. In the past this form has been classified as Amblyraja. georgiana. A.sp.anon differs from A. georgiana in form, colour and patternation, maturity, male clasper length, and distribution. It is larger than A.georgiana, with females attaining total lengths up 122.5 cm and males 117.5cm, compared with 96 and 101 for A.georgiana. Male A. sp.anon attain 50% maturity at a total length of 97cm, 13 cm greater than the length at 50% maturity for A.georgiana. Comparisons of colour and patternation were found to be consistent within each form, but significantly different between forms. Male A.georgiana, were found to have proportionally longer claspers to total length (2.77% difference between averages) than male A.sp.anon. 94% of captures of A.sp.anon were found at depths >1000m, where 85% of A.georgiana were caught in depths between 300-500m. We conclude that A.sp.anon probably a separate species from A.georgiana. For the purposes of CCAMLR assessments and monitoring it should be treated as a s eparate species from A.georgiana.