WG-FSA-94

Basing on materials of research expeditions and fishing cruises to the Kerguelen Islands shelf in the period from 1970 to 1991, dynamics of size- age structure of marbled rockcod (Notothenia rossii rossii) population is shown. Data on age determination for 1970-1989 (Tankevich, 1990) and the data collected in the joint Soviet-French expedition on board RTMA Orlinoye in May-Jine 1991 were used Read More
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In the season of 1990/1991, fishing operations in subarea 58.4.4. (Lena Bank) wer4e carried out by only one vessel - RTMA ZVEZDA KRYMA in April-June 1991. The total harvest in that period made 971 t of grey rockcod Notothenia squamifrons and 29 t of Patagonian toothfish Dissostichus eleginoides. The real catch excels the data in the Statistical Bulletin… nearly two-fold. In this connection it Read More
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To determine mackerel icefish Champsocephalus gunnari age, otolith mass was used. The material was collected in July0August 1987 during the joint Soviet-Australian expedition on board R/V PROFESSOR MESYATSEV to heard Island shelf area. The otoliths were weighted with an electric balance to within 0.0001 g. Then the obtained data underwent statistical processing with application of the cluster Read More
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An age-length key was prepared for Champsocephalus gunnari from the Subarea 48.3, based on the readings of otoliths randomly collected during the R/V Holmberg survey in Feb/Mar 1994. Small and medium sized fish (total length 12-33 cm) constituted the bulk of the samples (93%), while larger specimens (>33 cm) were scarce. At South Georgia, fish of age groups 1-4 were truly represented; at Read More
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Of 409 Notothenia coriiceps specimens tagged and released at Potter Cove, South Shetland Islands, in successive years from 1989 to 1992, 9 were recaptured at the same site after periods of 11-21 months. A comparison was carried out between the annuli found in scales removed before and after the period of liberty. In scales of those specimens recovered after 11-13 months, one extra annulus was Read More
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Areas of seabed within 50m depth contours down to 100m and within 100m depth contours from 100 to 500m have been estimated from soundings obtained during plankton and bottom trawl surveys around Elephant Island (the northernmost island of the South Shetland Islands) from 1977/78 to 1992/93. The results are presented on a fine scale grid of 15’ lat x 30’ long.

Patagonian toothfish, Dissostichus eleginoides, spawn over the continental slope from July to September. Eggs have been observed primarily in the upper part of the water column over 2200-4400 m bottom depth. Embryos in stage III and IV of their embryonic development are described. Hatching is likely to occur in October/November. Scales do not start to form before the fish are 64-74 mm long. Read More
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The diet composition and feeding intensity of mackerel icefish ( Champsocephalus gunnari) around Shag Rocks and the mainland of South Georgia was analyzed from 3,691 stomachs collected in January/February 1994. Main prey items were the amphipod hyperiid Themisto gaudichaudii, mysids (primarily Antarctomysis maxima), and krill (Euphausia superba) in the vicinity of South Georgia and T. Read More
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In 1991, the 0 age-class of C. gunnari were sampled at Shag Rocks on 18 January, off Possession Bay, South Georgia during 19-20 January and off much of the north-east coast of South Georgia between to 19 January to 19 February.
The size- frequency of fish at Shag Rocks contained two modes of 31-46mm and 55-87mm SL. however, off Possession Bay only one mode of 25-57mm SL was apparent. Read More
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As requested by the WG last year, the Secretariat circulated a list of software supported at the Secretariat with the Agendas and invitations to attend the working group. This document gives additional information on software and platforms available.

The progress of the fishery for Dissostichus eleginoides in Subarea 48.3 in the 1993/94 season is described. Fishing took place around Shag rocks and South Georgia, being concentrated in 4 of the 5 experimental areas. CPUE for 1994 appears similar to that from previous years except for Chilean vessels.

Traditional methods for estimating yield per recruit as a function of fishing mortality can result in inappropriate high estimates of yield that could lead to depletion of stocks because of widely varying recruitment patterns, overestimation of the abundance of the stock and age of the most recent survey. These problems are addressed in this paper by using stock projections to assess the Read More
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A long lining stock depletion trial was undertaken by the Korean longliner Ihn Sung 66 in January 1994 in accordance with CCAMLR Conservation Measure 69/XII and the Experimental Protocol circulated by the Secretariat in COMM CIRC 93/50. The results of this experiment are presented. Leslie and DeLury methods are tested using simulations to determine the most appropriate method. The Leslie Read More
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Methods for the calculation of the horizontal opening (swept area) of a bottom trawl are discussed. Details of the Scanmar trawl monitoring equipment used for making in situ measurements of horizontal opening and headline height of the FP-1 20 trawl during the 1993/94 UK fish stock assessment survey around South Georgia on the MV Cordella are provided. Empirical equations are derived for the Read More
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From the end of March to the beginning of May. 1993, during fishing operations for krill conducted by the m/t Lepus on the fishing grounds off South Orkney Islands: and South Georgia, investigations were• carried out to determine biological/fisheries characteristics of the exploited stocks. One of their goals was to determine the proportion of juvenile fish forms in krill concentrations. The Read More
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At the 1993 meeting of the Working Group on Fish Stock Assessment, members requested that work be undertaken to evaluate certain aspects of the experimental management strategy for the Antarctic crab fishery. A simulation model is proposed for conducting this work. Length frequency and catch rate data from the 1991/92 crab fishery are used to motivate the construction of an ontogenetic Read More
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The diet composition of the icefish Champsocephalus gunnari caught in the Subarea 48.3 in February/March 1994 was analyzed using the frequency of occurrence (%) method. Krill (Euphausia superba) followed by the amphipod hyperiid Themisto gaudichaudii were the main prey items at South Georgia and Shag Rocks; fish were found in the stomachs more frequently than in past seasons around South Read More
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A preliminary histological analysis on the ovarian development in Champsocephalus gunnari was carried out. Six stages of oocytary development were identified and are similar to those described for other species. A gonad maturation scale was elaborated and adapted to the macroscopic scale commonly used. Oocytary resorption processes were observed during ovarian maturation. In some cases the Read More
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A total of 63 hauls and 10 oceanographical legs were obtained. Of these, 44 hauls taken in Subarea 48.3 on a random stratified des n are used to estimate the standing stocks of the main commercial fish species along different methods, as well as their length frequency distributions. A change in surface water temperature of about -0.5 to -1.0 in a period of approximately 20 days was detected Read More
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Ten hauling for Dissostichus eleginoides were performed from the 11lth to the 21 of April 1994, wich were related between them, when they contact within a circle of 10 nm of diameter, whose center was at 55° 03’ S 36° 53’ W. Leslie Method was applied to the data. initial biomass was projected to 3244.8 nm2, obtaining an estimated biomass of 937.8 ton. Due to statistical limitations of these Read More
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Combined studies on the inner shelf and outer shelf of the Kerguelen islands (1989/90 to 1992/93) provides new informations about Champsocephalus gunnari stock. An inner shelf quaterly programme allows to identify each year, both from the ichthyoplanktonic surveys and bottom trawlings, an annual cohort. Strong differences in abundance of larvae are observed yearly. One cohort seems dominant in Read More
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