WG-FSA-SAM-04

We examine two alternatives to the survey recruitment/GY method for estimating toothfish abundance. An age structured production model (ASPM) is constructed and tuned to the CPUE series. The fit of the model to the CPUE series is not good, and there are several unexplained problems. The first is that the CPUE in the early 1990s did not decline as would be expected as the resource was initially Read More
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Target strength (TS) as a function of fish length (L) must be known to estimate fish density in acoustic survey. This TS-length function may be estimated by comparing in situ acoustic measurements with the fish size composition from trawl catches and should be accompanied with accuracy indices characterizing the uncertainty of its parameters. We show that the bootstrap–method is a highly Read More
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This report presents results from a desktop study to consider approaches to monitoring and assessing toothfish in New and Exploratory fisheries. We review standardised CPUE analysis, quantitative research longline surveys, experimental manipulation of fishing effort, tagging programmes, bottom trawl surveys of juvenile grounds, and acoustic surveys. Because of potential biases we believe that Read More
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Assessments of long-term sustainable yield using the Generalised Yield Model and the setting of total allowable catches (TAC) for Patagonian Toothfish, Dissostichus eleginoides, for the Heard Island Plateau region (Division 58.5.2) are based on data obtained from annual random stratified trawl surveys (RSTS) and from targeted commercial fishing operations via an observer program. The current Read More
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In subarea 48.3 mackerel icefish (Champsocephalus gunnari) are currently assessed by a bottom trawl survey, but evidence from predators and acoustics indicates that a considerable portion of the icefish biomass is in midwater and therefore missed by the bottom trawl survey. In January 2004, a short acoustic survey on FPRV Dorada showed that mackerel icefish, of all age classes, spend time in Read More
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At its 2003 meeting, WG-FSA recommended that investigations be undertaken to determine whether the method for estimating catches from illegal, unregulated or unreported (IUU) fishing developed by Agnew and Kirkwood (2002) for Subarea 48.3 could be applied to other CCAMLR areas (SC-CAMLR-XXII, Annex 5, paragraph 3.18).
The results of these simulations suggest that more information on IUU Read More
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We investigated local depletions of toothfish under concentrated fishing effort as a means of estimating toothfish density at South Georgia. Over the four years 2000-2003, we found 25 areas of 12’ by 12’ where there had been forty or more hauls in any particular year. There were 62 individual vessel fishing events in these areas over this period, 40 of which appeared to be depletions. Applying Read More
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This report presents results from a desktop study to determine the feasibility of conducting trawl surveys for juvenile toothfish in Subarea 88.1 (Ross Sea). Potential problems including a largely unknown juvenile distribution, variable ice cover, large survey area, and rough bottom topography, were considered using data from published and unpublished literature, the exploratory longline Read More
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The Secretariat has been developing Fishery Plans under the Regulatory Framework established by the Scientific Committee and Commission. In recent years, Plans have been drafted for the krill fishery in Area 48 (see WG-EMM-01/7, 02/6 and 03/28) and other fisheries (see WAMI-01/5, WGFSA-02/9 and 03/6). Each Fishery Plan draws together the history of management measures and fishery requirements Read More
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Analysis of Russia HAK-4M trawl catchabilities has been made in the paper. This trawl have been used when icefish bottom surveying. An analysis of total catchability and a differential one (that is catchability in relation to fish of different length) has been realized by models of probability statistical theory for fishing trawls. Influence of trawling speed, trawl configuration and Read More
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In 2003, WG-FSA and the Scientific Committee identified the need to rewrite and restructure the WG-FSA report. In early 2004, the extend and nature of the work required was developed in consultation between the Conveners of WG-FSA and WG-IMAF, and the Chair of the Scientific Committee, incorporating comments from other WG-FSA Members and the Secretariat. It was also agreed to contract Dr Inigo Read More
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Revision of icefish (С.gunnari) stock estimate in South Georgia Area was caused by elaboration of the following methodical aspects of trawl-acoustic survey: the processing method improvement for target strength estimates using in situ measurement data; the combination of trawl and acoustic surveys results for icefish biomass estimates .
We discus these methodical aspects and present the Read More
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We reanalysed 16 groundfish surveys at South Georgia to determine whether recruitment data used by the Working Group for toothfish assessments in 1999 and later were correct. We found several unexplainable errors. A new, corrected, series of recruitment estimates was derived using new procedures and 6 strata (3 depth strata each at Shag Rocks and South Georgia). It is easy to spot, visually, Read More
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These are the technical specifications of the software Fish Heaven: version 2.1.5. The specifications include a description of the object structure of the model, the process structure of the model and a mathematical description of the model.

In 2003, WG-FSA requested that the Secretariat supervise an external review of the GYM software and manual (SC-CAMLR-XXII, Annex 5, paragraph 9.18). The key steps in this proposed review included:
• Members providing guidance on the scope of the review;
• Members proposing appropriate independent experts to conduct the review;
• Reviewer to complete the review by end of June Read More
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Two variants of the ASPM assessment of the Prince Edward Islands toothfish resource are examined. One allows for the possibility of changes in somatic growth rate in response to increased food availability as resource abundance drops. The other permits annual fluctuations about a deterministic stock-recruitment relationship. A fit of the first variant yields the biologically implausible result Read More
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