Understanding the variation in krill diet during winter is crucial to elucidate the overwintering of krill in the Southern Ocean. The information on trophic variation of krill under ice-free waters during the winter can also provide the insight for understanding the response of krill to global warming. Stable isotope analyses (¹⁵N/¹⁴N and ¹³C/¹²C) were utilized to explore the variation in diet of adult krill with size and month during the winter season (June to September 2016) at the South Georgia. Stable isotope signatures indicated that there were no significant differences in δ¹³C and δ¹⁵N values between sexes of krill. Nitrogen isotope signatures suggested increasing carnivory with size of adults throughout winter. Carbon isotope signatures revealed reduced food sources for the larger adults during early winter, but all adults could feed on similar food items during middle to late winter. The trophic niche of adults was similar during the winter season at the South Georgia. Our results provide insight for the diet of adult krill in the food-limited season and should be useful in understanding the energy transfer in the marine food web in the South Georgia ecosystem. Moreover, the information derived from this study can also be used to support krill fishery management and understand the interaction between krill population, top predators and fishery.

New Zealand carried out a 40-day voyage to the Ross Sea from 8 January to 16 February 2019 using the research vessel Tangaroa. The purpose of this multi-disciplinary research voyage was to increase knowledge about key environmental and biological processes in the Ross Sea region of Antarctica and the Southern Ocean, and thereby improve understanding of ecosystem function and likely responses to future change. The focus was on providing information relevant to the recently established Ross Sea region Marine Protected Area to allow scientific evaluation of its ecological status, spatial adequacy, and effectiveness. The eight voyage objectives spanned topics ranging from oceanography to bacteria to whales.

Satellites Over Seals (SOS) is a crowd-sourced, remote sensing approach to identify presence/absence patterns of the Weddell seal (Leptonychotes weddellii), and has recently been adapted for crabeater seals (Lobodon carcinophagus) in the Weddell Sea region. Satellites Over Seals provides an efficient method to screen large numbers of images (and hence area) for undertaking census counts of Weddell and crabeater seals.

Using high-resolution satellite imagery (VHR; 0.3–0.6 m resolution) and the online platform, Tomnod, to host VHR for the public (i.e. “the crowd,”) to search, we collected presence/absence data for Weddell seals on images from November 2010 and 2011. In a second campaign, we selected images of the pack ice acquired during October 2018 in the Weddell Sea to identify presence/absence of crabeater seals.

In both campaigns, our goal was to identify probable presence/absence to learn where closer inspection — and abundance estimation — should be concentrated. More than 325 000 citizen scientists searched 852 VHR images, composed of a series of tiles called “maps”, across both campaigns. The circum-Antarctic search for Weddell seals covered 268 611 km² of fast ice continent-wide and the crabeater seal campaign covered about 18 000 km² of pack ice. Using consensus-based algorithms on images identified by the crowd to have seals present, we identified Weddell seal presence on only 0.55% of maps (total n=1 116 058) within the available fast ice during 2010 and 2011.

Preliminary data on crabeater seal presence in the Weddell Sea region suggested presence on 3.3% of maps. Comparison with images searched by experts showed that the rate of false negative detections for Weddell seals was low (1.7%), although false positives were high (67%). The crabeater seal detections (3.3% of maps with seal presence) reported here were conducted by experts, and on a subset of available images (of area totalling 738 km²).

We assess image resolution, quality, training and outreach for future campaigns, and effectiveness of implementation toward encouraging remote sensing and citizen science as solutions to learn about Southern Ocean predators.

The Antarctic krill (Euphausia superba) is a key species in the Southern Ocean ecosystem and an important link in the food web of the Antarctic ecosystem. The trophic information for this species during the transition from the austral fall to the winter is important to understand its poorly known overwintering mechanisms. However, the few studies on the topic differ in their results, in terms of both spatial and temporal variables. We investigated the size dependence and monthly and regional variation in δ¹³C and δ¹⁵N values of adult krill in the Antarctic Peninsula, in the austral fall (April to May) and the early winter (June). We aimed to examine the trophic variations of krill occurred during this period, and the relationship between krill and their feeding environment in the Antarctic marine ecosystem. The following results were obtained: (1) no significant relationship was observed between size and the δ¹³C value of krill, but the δ¹⁵N value of krill presented a remarkable association with size, (2) the δ¹³C values of krill increased during the austral fall, but no remarkable variation existed at the onset of winter, and the δ¹⁵N values were not significant different during this period, (3) mean δ¹⁵N values of krill differed significantly between the Bransfield Strait and the South Shetland Islands. Our data imply that adult krill present size-, season-, and region-dependent trophic variation during the transition from austral fall to early winter in the Antarctic Peninsula.

The current CCAMLR protocol specifies daytime acoustic sampling in order to avoid issues of krill migrating too close to the surface to be acoustically detected, as well as potential issues of diel changes in acoustic scattering strengths. However, due to logistic constraints, acoustic data were collected both during day and night for the 2019 Scotia Sea large-scale krill monitoring survey. Data from upward-looking, stationary platforms offer unique opportunities for assessing the effects of krill vertical distribution on survey results. The Institute of Marine Research, Norway has on a regular basis deployed stationary platforms in the main area for commercial krill harvesting at the South Orkney Islands since 2014, and in this report some of these data have been analysed in order to provide an estimate of the magnitude of bias introduced by night-time acoustic sampling. We found great temporal and geographical variation in DVM (Diel Vertical Migration). During February and March, the time period covered by the 2019 survey, the frequency response data obtained using an upward looking NORTEK broadband echosounder suggested that 13 % of the macroplankton backscatter originated above a depth of ~20 m during daytime, while 24 % was found above ~20 m during night. A swarm detection approach suggested a similar pattern, 7 % of aggregated backscatter was found above ~20 m during daytime, and 22 % during night.

We report here on the existence of seasonal fish migrations into a krill hotspot, utilized both by central place foragers and the industry. We do not have trawl samples overlapping with the acoustic data, but the behaviour displayed suggests that the fish are planktivorous. Furthermore, the acoustic data suggest that they may form high density schools during daytime, that could not be separated from krill on a single frequency. Trawl catches in the area during 2019 gave high densities of mackerel icefish, so this species is a likely candidate, if these targets are swimbladderless notothenoids, their frequency response may be similar to that of krill at the commonly used frequencies of 38 and 120 kHz.

Standard protocols for processing of echosounder data are geared towards the estimation of biomass indices of pelagic organisms. More transient visitors to the watercolumn however also give echoes, and the data provided by the echosounders may be used to assess the behaviour of these organisms, as well as their interactions with the pelagic residents. Using freely available software and neural networks developed for general image recognition, we detected diving events by air-breathing predators in a 1 year dataset from an acoustic lander located close to the South Orkneys. The analysis documented clear patterns in the dive data with regards to time of year as well as time of day. At the temporal scales analysed the data did not suggest a positive correlation between backscatter of pelagic aggregations and the detected diving activity at this location.

Domain 1 marine protected area (D1MPA) proposal has been developed sin 2012 and now has been intensively discussed. Its implementation will establish a new scenario for the current krill fishing fleet dynamic, therefore it is necessary to understand what represent each D1MPA zones for the fishery. We analysed the trend of different fishing indicators among the D1MPA zones during the period 2013-2017, including as an independent zone the main fishing hotspot established recently in Bransfield Strait. Bransfield zones are crucial for the current fishery performance; SSI zones are secondary used when fishing yields decrease; and Gerlache seems to provide promising fishing tendencies, but its stability is uncertain.Domain 1 marine protected area (D1MPA) proposal has been developed sin 2012 and now has been intensively discussed. Its implementation will establish a new scenario for the current krill fishing fleet dynamic, therefore it is necessary to understand what represent each D1MPA zones for the fishery. We analysed the trend of different fishing indicators among the D1MPA zones during the period 2013-2017, including as an independent zone the main fishing hotspot established recently in Bransfield Strait. Bransfield zones are crucial for the current fishery performance; SSI zones are secondary used when fishing yields decrease; and Gerlache seems to provide promising fishing tendencies, but its stability is uncertain.

Currently, several approaches to FBM have been tabled to CCAMLR – Risk Assessment (RA: Constable et al. 2016), experimental fishing (EF: WS-SM-18/05) and Decision Rule approaches (DR: Watters et al. 2016), and recently a more empirical approach using a combination of fishing fleet-collected acoustic data and predator foraging information (EMP: Nor/Chil/China 2017).   Each approach has substantial merit in terms of the utility of available data. However, none currently offers a holistic solution in their own right.  In 2017, the Scientific Committee encouraged coordination among the various approaches towards developing a practical FBM approach (SC-36 para.3.23).  We present a revised approach to that which was presented by Norway, Chile and China to SC in 2017, and provide a framework for incorporating aspects of each currently tabled approaches from RA, EF, DR and EMP into potentially one that can be developed to become relatively easy and quick to operationalize.  Finally, we propose a package of work that seeks to demonstrate the practicality of its implementation that could provide CCAMLR with a “dress rehearsal” of how an interim Stage 2 FBM approach could be rolled out.

This paper describe tests with the Sailbuoy during the 2019 RV Kronprins Haakon cruise in the Antarctic. The trials were successful giving data during continuous operations from end of January to mid February. We present data demonstrating capabilities to run survey transects, to observe variability at a location (future comparison with mooring data when available) and surveying predator prey-fields. Perspectives and plans for the development of a “Sailbuoy for krill” including advanced on board processing in accordance with our funded project, is presented and discussed.