To identify the important prey items for pre-recruit Antarctic toothfish in the SSRUs 58.4.1.C, 58.4.1.G, 58.4.1.E, and 58.4.2.E, their stable carbon and nitrogen isotope ratios were determined. Sampling efforts were made during a longline survey of pre-recruit toothfish from commercial fishing vessel. In the previous studies, similarities in total FA compositions and the FA profiles in muscle tissue of Antarctic toothfish, bycatch specimen and icefish in the stomachs indicated a trophic connection between the toothfish and icefish. In this study, similarities in the δ13C values δ15N values of Antarctic toothfish indicate they occupy same trophic position irrespective of the area, body size, sex, and gonadal maturity. The combination of stable isotope ratios and fatty acid profiles can be effectively used to trace the trophic transfer from organic matter sources to higher trophic levels through food chains. Further studies on the trophic relationship between Antarctic toothfish and other animals by collection and subsequent biomarker analyses such as stable isotope analysis after lipid extraction, stomach contents analysis, and fatty acid analysis are needed to better understand the carbon flow through the Antarctic ecosystems.

This paper presents an update of the metrics of capacity and capacity utilisation presented in WG-SAM-14/19 and WG-FSA-15/09 in order to monitor trends in capacity in exploratory toothfish fisheries in Subareas 88.1 and 88.2. The updated metrics show the same pattern as the metrics based on the data up 2016 and do not indicate an excess capacity in the fishery. As indicated previously, based on a measure of potential daily fishing capacity and the catch limit for an area the notified fishing capacity in some management areas is in excess of the level that would allow the Secretariat to forecast and issue a timely closure notice using the current fishery forecasting procedure.

Data on fish bycatch in the krill from Commercial catch data (95 513 hauls) and CCAMLR SISO data (11875 hauls) was used to examine the frequency of occurrence, proportion by mass, length-frequency distribution and geographic provenance of the key fish taxa reported. There was a high degree of overlap in the most frequently reported taxa in the C1 data and SISO data, with Lepidonothen larseni and Chaenodraco wilsoni the most frequently reported in both datasets. The estimated total annual mass of fish by-catch in a 300 000 t krill fishery would be 370 t, comprising 40% Champsocephalus gunnari and 30% Lepidonotothen larseni. The length-frequency distribution of all taxa for which >100 fish were measured had modal size class of <10 cm. The fish species taken as by-catch in the krill fishery are the same species (and size classes) as those reported in the diet of ‘krill-dependent’ predators. There is evidence of both an increase in the data quality from the observer scheme, as reflected in the reduced confidence intervals around the frequency of occurrence data, as well as an increase in the fish by-catch reported in the commercial krill catch data. A systematic method for observers to record fish by-catch and increases in observer coverage in the krill fishery has provided an increase in the data available with which to examine the magnitude of fish by-catch in the krill fishery.

ASOC strongly supports the recommendation of WG-EMM-16 that Conservation Measure 51-07 should be retained while alternative strategies and feedback management (FBM) are under evaluation. Discussions at WG-EMM-16 provided further evidence that concentrating krill fishing operations in areas being used by land-based predators puts predators at risk from localized depletion. Consequently, ASOC expects CCAMLR to endorse the scientific advice from its working group. Although it has some weaknesses, CM 51-07 has minimized the risks of localized krill depletion and therefore should not be allowed to lapse. ASOC also urges SC-CAMLR and the Commission to develop additional means of preventing overlap between fishing locations and predator foraging areas to minimize the risk of fishery impacts on krill predators.

A project is proposed to provide CCAMLR with a detailed description of all species which are or have been subject to exploitation at one time in the Southern Ocean. It is envisaged that CCAMLR will benefit considerably from the project both in terms of its publicity and perception in the context of international organisations.  This paper provides a brief outline of the work proposed, work priorities, possible participation, length of the project and costs incurred.