As a contribution to the joint effort on the large-scale synoptic krill survey of Area 48, the Chinese krill fishing vessel Fu Rong Hai conducted the survey in the Subarea 48.1 from 2 February to 10 February 2019. A total distance of about 875 n. mile transect acoustic data was collected using a hull-mounted Simard EK60 echosounder (38, 70 and 120 kHz), and 10 planned stations were sampled for krill biology using a commercial midwater otter trawl.  Acoustic data processing were carried out generally following the procedures applied in the CCAMLR 2000 survey analyses, and estimates of krill density were based on the 120 kHz data attributed to krill using the swarm-based method as well as the two-frequency (S_v120-38kHz) identification methods. Results show that mean krill areal biomass density is relatively higher than the estimates of the CCAMLR2000 survey in the same area. Main objective of the present work is to introduce the implementation and preliminary results from the synoptic survey conducted by the Chinese vessel, and further cooperated analysis on the survey data might be done in the upcoming Subgroup on Acoustic Survey and Analysis Methods (SG-ASAM) meeting.

A multidisciplinary ecosystem survey in the eastern Indian sector of the Antarctic (CCAMLR Division 58.4.1) with a focus on Antarctic krill was carried out by Kaiyo-maru during the 2018/19 season for 53 days. The survey consisted of 2 survey periods: Leg 1 (from 15 December 2018 to January 2019; 24 days) and Leg 2 (from 26 January to 23 February 2019; 29 days). Leg 1 was commenced at ice edge on 80°E and ended at ice edge on 120°19.0’E. Leg 2 was commenced at 63°00.0’S on 150°00.0’E and ended at ice edge on 125°50.0’E. Two small scale oceanographic surveys (off the Mertz Glacier Tongue and the Totten Glacier) were also conducted during Leg 2. RMT tows were carried out at 72 stations (40 predetermined and 29 targeted stations with combination of both at 3 stations). SUIT tows were carried out at 28 stations. Quad NORPAC tows were carried out at 44 predetermined stations. Narrowband echosounder (38, 70, 120 and 200 kHz) data to estimate biomass of Antarctic krill were recorded along predetermined tracklines for 2,519 n.miles. Broadband echosounder data were recorded at 24 targeted RMT stations to estimate length distribution and swimming angles of Antarctic krill acoustically. The mass density and sound-speed contrasts against surrounding seawater of zooplanktons were measured 14 and 12 times, respectively. SADCP and PDR data were continuously recorded along the tracklines. A total of 101 CTD and 150 XCTD casts were made for physical and chemical oceanographic studies. Six types of autonomous profiling floats and buoys were deployed at 18 locations. Surface oceanographic environment data were continuously recorded along the tracklines. Sea ice (18 samples) and iceberg (15 samples) were collected for physical and chemical oceanographic studies. A total of 26 CTD casts were made for biological oceanographic studies. A total of 339 schools with 552 individuals of marine mammals were sighted during 1,249 n.miles of sighting effort along the tracklines. A total of 8,616 individuals of seabirds were sighted during 1,257 n.miles of sighting effort along the tracklines. Biological video recordings were made 25 times using 6 types of video recording devices. A number of analyses using obtained samples and data are in preparation and the results will be presented to the expert groups of SC-CAMLR.

China, Italy and Republic of Korea submitted to the next coming CEP XXII - ATCM XLII a proposal for the designation of a new Antarctic Specially Protected Area (ASPA) at Inexpressible Island and Seaview Bay, Ross Sea. The co-proponents have prepared the draft ASPA Management Plan annexed to this paper, in accordance with the requirements of Annex V to the Protocol on Environmental Protection to the Antarctic Treaty and the Revised Guide to the Preparation of Management Plans for Antarctic Specially Protected Areas (Resolution 2, 2011). The proposal is submitted to CCAMLR for its consideration, in accordance with ATCM Decision 9 (2005)

We provide a summary of environmental change in the Southern Ocean over the period of satellite observaton (1981 to present). The environmental data we consider are: (1) chlorophyll-a concentration from merged observation of SeaWiFS and MODIS-Aqua (1987–2019); (2) sea-surface temperature (SST) from the AVHRR series of NOAA satellites (1981–2019); (3) spatial gradient of SST (as an indicator of ocean fronts) from the same AVHRR observations; (4) sea ice concentration from microwave satellite sensors (SMMR, SSM/I); (5), net primary productivity (NPP) using the vertically-generalised productivity model (VGPM); (6) estimates of mixed layer depth from the data-assimilating US Navy hindcast model HyCOM (GLBu0.08); and (7) incident light intensity at the sea-surface. The data show heterogenous patterns of environmental change across the Southern Ocean over the last 4 decades. Key results are: (1) warming of the ocean surface north of the southern limit of the ACC and slight cooling to the south; (2) evidence of movement north of the Subantarctic Front; (3) increasing chl-a and NPP in the Subantarctic Front and around the southern limit of the ACC except in the Ross Sea region; (4) decreasing chl-a and NPP in the Ross Sea sector and on the Antarctic continental shelf; (5) gradual loss of sea-ice in the Amundsen Sea and increasing sea-ice in the Weddell, Bellingshausen and Ross Seas; (6) deepening of the mixed-layer near the Polar Front, contrasting with shallowing in the Ross Sea region, and both increases and decreases in different parts of the Weddell Sea; (7) increasing trends in incident light intensity in Subantarctic waters and generally decreasing trends near the Antarctic continent.

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.