CCAMLR

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 efficient method of estimating the parameters of TS-length function and emphasize that calculation results depend on the adopted mapping rule of fishing data into acoustic data. The bootstrap methods has been applied to data from icefish measurements. The TS-length functions based on full probability density function (PDFs) of fish length and target strength at 38 kHz and truncated PDFs are presented. We reveal that it is probably necessary to use different regression equations for different length ranges.

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 it would be imprudent to rely solely on any one of these methods at the present time. We recommend that tag recapture experiments, or trawl surveys, be used in conjunction with experimental manipulation of effort to monitor toothfish – and perhaps as importantly – the wider ecosystem effects of the toothfish fisheries. We further recommend that simulation studies be carried out to determine the best way to use the effort manipulation approach in all New and Exploratory fisheries, and in particular the current active fisheries (e.g., Subareas 88.1 and 88.2, and Division 58.4.2). Such studies should examine the spatial and temporal scales required for this approach and possible methods (and sample sizes) required to implement the pulsed fishing experiments.

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variable ice cover, large survey area, and rough bottom topography, were considered using data from published and unpublished literature, the exploratory longline fishery and previous research cruises.
The major limitation on a trawl survey in the Ross Sea is ice cover. On average over the last three years, 63% of the seabed area from 0–600 m depth was not fishable in January–February because of ice. Ice cover varied greatly between years, with the untrawlable area ranging from 31% in 2002 to 89% in 2002. Less than 10% of the potential trawl survey area was fishable in all three years.

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 Everson to develop certain elements of the restructure (see SC CIRC 04/11 and 04/16). Dr Everson’s first task was to prepare a number of draft fishery reports for consideration by WG-FSA-SAM.
This paper contains the background circulars (SC CIRC 04/11 and 04/16) and four restructured fishery reports which have been drafted by Dr Everson.

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 2004 and report to WG-FSA-SAM at its meeting in July 2004;
• WG-FSA-SAM to consider the review and advise WG-FSA.
A call for expressions of interest for the review was made in March 2004 (SC CIRC 04/06); the deadline for responses was 23 April. Members did not provide formal feedback or expressions of interest, and the window of opportunity for conducting a review before the 2004 meeting of WGFSA-SAM passed.
As a way forward, it is proposed that WG-FSA-SAM determine exactly what the group would like to see in terms of an external review of GYM. The Secretariat could then send a new call for tenders in August 2004. Members could then evaluate tenders at the meeting of WG-FSA in October 2004, and SC-CAMLR-XXIII could consider the outcome of this process and secure appropriate funding for a review in 2005.

A compact, autonomous deep sea video system designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with the Southern Ocean benthos, has a wider application in deep-sea marine research. The use of the system as a drop camera for broad-scale and rapid deep-sea benthic habitat assessment, during a recent AAD marine science voyage on the shelf-break of East Antarctica, greatly improved the efficiency of selection of sites for quantitative sampling. The system is also promoted for estimates of krill biomass, swarm dynamics and reproduction, and ground-truthing remote data for habitat mapping. The main advantages of using this system as a drop camera included: 1. Rapid: Three, two minute replicates of footage at 1000m, including recovery and viewing of footage was typically accomplished in well under one hour. 2. Compact: Simplified deck operations due to the autonomous nature, compact architecture, and absence of camera to ship umbilical. 3. Simple to operate: No requirement for opening the pressure housing to download data leads to reduced training needs. 4. Robust: The unit was deployed successfully while the vessel was surrounded by sea ice.

We provide an update on progress in the FRDC and industry-funded project “Demersal interactions with marine benthos in the Australian EEZ of the Southern Ocean: an assessment of the vulnerability of benthic habitats to impact by demersal gears”. This project commenced in 2006 and is due to conclude with the publication of a final report in late 2011. Outputs of this project, including novel technologies and unique datasets for quantifying the dynamics and extent of the interactions between demersal fishing gears and deep sea habitats in the Southern Ocean, will assist with providing key components for the development of robust impact risk assessments and adaptive management strategies necessary to ensure CCAMLR will achieve its goal of avoiding significant adverse impacts to benthic assemblages.

Conservation Measure 22-07 (2008) requires vessels fishing in the Ross Sea (and most areas south of 60°S) to collect and monitor longline bycatch for VME taxa, and implement a move-on rule if required. To ensure effective monitoring, an evaluation of VME taxa classification by Scientific Observers from four vessels in the Ross Sea Antarctic toothfish longline fishery during the 2009-10 season was conducted. Scientific Observers classified invertebrate bycatch using a revised and expanded VME taxa classification guide, and retained 1109 samples from 1272 longline segments for subsequent classification by parataxonomists and/or taxonomists, from which 4555 specimens were identified. Improvements made to the classification guide, along with specific training, benefitted the accuracy of data collection. Comparison of the observer’s classification versus the taxonomist’s classification showed that for most groups, the observer classifications were reasonably precise (88% accuracy). Some problems in distinguishing demosponges and hexactinellid sponges, sponges from ascidians, and stylasterid hydrocorals from gorgonian corals remains. Scientific Observers rarely classified non-VME taxa as VME taxa (23 of 1008 samples). In the Echinodermata group, brittle stars (a non-VME taxon) were sometimes recorded as snake stars (a VME taxon). Briefings prior to sailing and additional training materials can address most remaining issues.