The scientific survey was conducted by the Greenstar (KOR) in the research block 883_3–883_5. Due to extreme ice conditions covering the southern part of 88.3, the Janas (NZL) was not able to conduct its part of the survey. The total catch of D. mawsoni was 38,856 kg comprised of 1,380 individuals. The CPUE for Dissostichus mawsoni indicated regional differences among the research blocks. While CPUE in blocks 883_3 and 883_4 showed similar values of 0.1369 and 0.1466 kg/hook, research block 883_5 was extremely low showing 0.0273 kg/hook. Tagging rate and tag overlap in Subarea 88.3 were 5.2 fish per tonne and 72%. The length frequency of D. mawsoni exhibited a bimodal distribution with modes near 70 cm and 150cm. Female maturity stage showed a regional pattern, with the stage 2 accounting for 47.8%, 28.1%, and 25.6% in the areas of 883_3, 883_4, and 883_5, respectively. To get biological information of D. mawsoni, otolith, stomach contents, gonad and muscle were collected. Water temperature and salinity were measured at 6 locations during the survey in Subarea 88.3. Notification of research for the agreed 2018-19 fixed-effort survey as detailed in WG-FSA-17/40 is included with thesame catch limit of 235 t as in 2017-18.

Japan and France propose a plan to continue investigate the populations of Patagonian toothfish (Dissostichus eleginoides) in the Division 58.4.4b during the next fishing season (2018/19) from 2017/18 onwards, using standardized longline gear, and established tagging techniques. The proposed research is relevant and take into account issues raised by the Scientific Committee (SC-CAMLR-XXXIII, paragraph 3.208), which requested that research activities be coordinated between France and Japan so that selectivity and catch rates can be standardized across the vessels and impacts of depredation be minimized.

Additional outcomes of the research relate to documenting the degree of depredation, tagging toothfish for biomass estimation and for stock linkage studies, and collecting information on distribution, relative abundance, and life history of bycatch species.

The plan represents a continuation of previous surveys by Japan and France, without significant change from the previous research activities.

Japan and South Africa propose to continue investigating the population structure and various demographic parameters of Antarctic toothfish (Dissostichus mawsoni) in the Subarea 48.6 in 2018/19 using standardized longline gear, established tagging techniques, and pop-up tags. The proposed research is pertinent to issues raised by the Scientific Committee (SC-CAMLR-XXXV, paragraph 3.3.252-3.265) and will supplement and expand previous efforts to characterize the local toothfish populations in the area to better understand stock structure, movement patterns and improve estimation of population characteristics and thereby contribute to the development of spatial population models and assessments in support of management advice.

Additional outcomes of the research include documenting relative abundance of Antarctic toothfish and Patagonian, tagging toothfish for biomass estimation and for stock linkage studies, and collecting information on distribution, and life history of bycatch species.

The plan represents a continuation of previous surveys by South Africa and Japan without significant change from the previous research activities. From 2018/19 fishing season, Norway had considered the joint survey participation, but due to various circumstances Japan and South Africa received an offer to withdraw their participation.

Antarctic krill (Euphausia superba)—one of the most abundant animal species on Earth—exhibits a five to six year population cycle, with oscillations in biomass exceeding one order of magnitude. Previous studies have postulated that the krill cycle is induced by periodic climatological factors, but these postulated drivers neither show consistent agreement, nor are they supported by quantitative models. Here, using data analysis complemented with modelling of krill ontogeny and population dynamics, we identify intraspecific competition for food as the main driver of the krill cycle, while external climatological factors possibly modulate its phase and synchronization over large scales. Our model indicates that the cycle amplitude increases with reduction of krill loss rates. Thus, a decline of apex predators is likely to increase the oscillation amplitude, potentially destabilizing the marine food web, with drastic consequences for the entire Antarctic ecosystem.

A dominant Antarctic ecological paradigm suggests that winter sea ice is generally the main feeding ground for krill larvae. Observations from our winter cruise to the southwest Atlantic sector of the Southern Ocean contradict this view and present the first evidence that the pack-ice zone is a food-poor habitat for larval development. In contrast, the more open marginal ice zone provides a more favourable food environment for high larval krill growth rates. We found that complex under-ice habitats are, however, vital for larval krill when water column productivity is limited by light, by providing structures that offer protection from predators and to collect organic material released from the ice. The larvae feed on this sparse ice-associated food during the day. After sunset, they migrate into the water below the ice (upper 20 m) and drift away from the ice areas where they have previously fed. Model analyses indicate that this behaviour increases both food uptake in a patchy food environment and the likelihood of overwinter transport to areas where feeding conditions are more favourable in spring.

In Division 58.4.3a, since 2012, research fishing has been conducted in the research block by three vessels using longline: “Shinsei Maru No. 3” (Japan), “Saint André” (France) and “Mascareignes III” (France). The first Franco-Japanese exploratory longline fishery research plan for Dissostichus spp. in Division 58.4.3a (WG-FSA-16/55) was presented to WG-FSA-16, which included research objectives, methods and milestones in accordance with Conservation Measure 41-06 and associated measures. In October 2017, the Scientific Committee agreed that the research plan is appropriate to achieve its objectives (SC-CAMLR-XXXVI, para. 3.121). France and Japan commonly notifies their intention to continue their exploratory fisheries in Division 58.4.3a over the coming years in order to contribute to the tagging program and to achieve a robust stock assessment. We present here a proposal for the continuation of the research plan as set out in WG-FSA-17/55, and taking into account the Scientific Committee’s recommendations.