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NIWA FINDS ROSS SEA FISH A survey led by marine scientists Dr Stuart Hanchet, from NIWA, and Dr Hyun-Su Jo, from Korea, has found high densities of young toothfish in the southern Ross Sea. The survey is the first in a series that will monitor numbers of young Antarctic toothfish in the Ross Sea region. Antarctic toothfish (Dissostichus mawsoni) are found at depths down to 2000m. Fish mature at a length of 1.2-1.3m, and adults live to an average age of 20 to 24 years. Dr Hanchet says the survey will monitor numbers in the Ross Sea region and it is the first in a series looking at both the number and size of fish that are between five and 10 years old and less than a metre in length. Information is currently collected to monitor the abundance of adult toothfish, but there is not the same quality of information for young fish. By tracking this part of the population, researchers hope to ensure that catch limits are set at the correct level in the future. The main objective of this first toothfish survey was to establish the feasibility of developing a time-series of surveys to monitor young toothfish in the southern Ross Sea using standardised commercial longline fishing gear. Fifty-nine random locations were surveyed using longlines, each comprising 4600 hooks, set for up to 24 hours, within a survey area of 30,000sq km. They caught mainly 700mm-1m toothfish (at times over 100 individuals per line), in depths from 300-900m. The fish caught were then measured and sexed, with biological samples taken for further analysis back in New Zealand. The survey also demonstrated the feasibility of collecting samples for wider ecosystem monitoring. A large number of samples of muscle tissue and stomachs were collected from Antarctic toothfish and several other fish species, and will be analysed to understand feeding habits and relationships with other organisms in the food chain. Countries fishing in the Ross Sea must tag a certain number of toothfish for scientific research, and carry out biological sampling of toothfish, as well as other fish species caught as by-catch. "Tagging information has been critical to developing a comprehensive stock assessment model for the fishery to estimate biomass and set catch limits," says Dr Hanchet. Under the provisions of the Antarctic Treaty, the Antarctic toothfish fishery is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). CCAMLR sets the rules for fishing in the CCAMLR Convention Area, which includes the Ross Sea, and all participating member countries have to operate within these rules. The survey is a New Zealand-led scientific contribution to CCAMLR. The survey and tagging programme was designed by marine scientists in NIWA and the Ministry of Agriculture and Forestry (Fisheries science), and involved a collaboration with the fishing industry, which provided the platform for the survey, the Sanford vessel San Aotea II. Background facts: • Fishing for Antarctic toothfish in the Ross Sea region began in 1997-98. • The number of licensed fishing vessels in the Ross Sea is carefully controlled by CCAMLR. In the current 2011/12 season, 18 vessels were permitted to fish, of which 15 actually fished. • The total catch limit this season was 3282 tonnes. • New Zealand's participation in the Ross Sea toothfish fishery is worth NZ$20-30 million per annum in export earnings. • The New Zealand delegation to CCAMLR comprises officials from the Ministry of Foreign Affairs and Trade, the Ministry of Agriculture and Forestry, and the Department of Conservation. Representatives from the fishing industry and environmental NGOs have been included in the New Zealand delegation in past years. • There are two toothfish species in Antarctica. The Antarctic toothfish is found around the continent in Antarctic waters, and the Patagonian toothfish, which is found further north in sub-Antarctic waters. In the mid to late-1990s the Patagonian fish was heavily over-fished by illegal vessels. The stocks are believed to have stabilised, and in some cases re-built. "The world's leading inspection, vertifi cation, testing and certifi cation company" SGS NEW ZEALAND LTD NATIONAL SHIPPING OFFICE: 17 Maurice Road, Penrose 1061 PO Box 13 518 Onehunga 1643, Auckland Ph: 0800 174 025, Fax: 09 636 6054 Email: nz.auckland.industrial@sgs.com Construction Survey, Cargo Surveying, Safe Ship Management, Equipment Inspection and Testing (including Radiography, Thickness and Crack Testing etc), Cranes, Lifting Equipment, Pipeline, Boilers and Pressure Vessels Design Verifi cation and Certifi cation, Water and General Laboratory Testing, Vibration and Oil Analyses. ISO 9001:2008, ISO 17925, ISO 17020:2000 Marine Surveying, Design Approval and new www.nz.sgs.com 68 Professional Skipper May/June 2012 New Plymouth, Wellington, Christchurch, Timaru, Invercargill, Dunedin OFFICES IN: Auckland, Tauranga, Napier, Rotorua, VIP.S85