CCAMLR

The northern geographical distribution of the toothfish Dissostichus eleginoides, reaches the Exclusive Economic Zone of Uruguay. The species was firstly cited for the uruguayan waters by Devincenzi in 1924, and it is usually found by fishing trawlers between 900 m and 1200 m of depth, along the submarine continental ridges. Since 1997 some fishing vessels, like the F/V “Viking Sky”, started to capture the toothfish using conic bottom fishing-traps with sardine and squid frozen bait.
The F/V “Viking Sky” performed this fishing trip between the 2 of september to the 11 of october of 2001, with a Scientific Observer from DINARA on board. The ship looked for fishing zones both in uruguayan and international waters (FAO Statistical Area 41). Three different fishing zones were geographically determined:
Fishing zone South Latitude West Longitude
Northern Zone I 37.57 54.08
37.48 53.43
Southern Zone 42.17 57.57
42.51 58.33
Northern Zone I 37.42 53.40
37.09 53.42
The Southern Zone had the best fishing-yield: 5,7 Kg./trap/day; while the Northern Zones I and II had a very similar but inferior yield: 4,96 Kg./trap/day and 5,38 Kg./trap/day.
The average, modal and median length calculated for each sex were the following:
Males Females
Average length 86.18 cm 87.25 cm
Modal length 90.00 cm 85.00 cm
Median length 89.00 cm 86.00 cm
The majority of the sampled individuals of both sexes were determined in the grade 2 of gonadic maturity (84% of males and 89% of females), which means that most of the capture were juvenile. The selectivity of the fishing traps were determined in 59 cm of fish length, as the minimum size captured.
The deep-water lobster (Crustacea) Thymops birsteini; and grenadiers Macrourus spp. were captured as incidental fishing by the bottom traps.

The icefish fishery on the Kerguelen shelf has been stopped after the1994/95 fishing season when 3889 tonnes of Champsocephalus gunnari were landed (see CCAMLR statistical bulletins) because yields were not enough high and the lucrative fishery of Patagonian toothfish Dissostichus eleginoides deverted fishermen from these specific shallow fishing grounds. However to follow the situation in the area the fishery licences for trawlers have been linked to the obligation of conducting some experimental cruises in the traditionnal area of fish aggregations. Such cruises occur regularly with two trawlers from 1996/97 to 2001/2002, the last season of trawling in the Kerguelen EZ. Preliminary results do not show an increasing of the icefish’s abundance in the surveyed area and biomass seems very low. It is a different situation comparitively to the Heard islands stock where biomass allows catches. This situation is not clearly explained and various hypothesis are proposed: no recovery in a too depleted stock, bad recruitement or emmigration in relation to the ENSO 1998 effect in the vicinity of the islands, increasing of predation by fur seals Arctocephalus gazella growing the population. Other analysis (total and species by species biomass, importance of the by -catch in the area) will follow this preliminary analysis.

Kirkwood and Agnew (2001, paper WG-FSA-01/48) proposed an ad hoc method for estimating selectivity curves for toothfish taken by longliners around South Georgia and Shag Rocks over the period 1995 – 1999. This method was applied by WG-FSA-01, with minor amendments, to estimate annual age-specific selectivities for the years 1995 – 2000 for input to the GYM assessment. In this paper, I propose a revised method for estimating the selectivities based on an assumption that the proportions of the total CPUE in an area for a particular length class that are taken in different depth zones are Beta-distributed. This removes some of the ad hoc nature of the former estimation method. The method is illustrated by application to data for 1995 – 2000.

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.