With the goal of collating, synthesizing, and working towards coordination of U.S. research and monitoring in the RSRMPA, the U.S. Ross Sea science community convened a virtual workshop on 26-27 April 2021. The workshop included 51 participants (see Appendix A) representing active U.S. Ross Sea scientists as well as representatives of major U.S. science funding institutions (National Science Foundation - Office of Polar Programs, OPP, NASA, NOAA, Pew Charitable Trusts, and Schmidt Ocean Institute). The array of participants was multi-disciplinary, with Ross Sea expertise spanning biophysical (weather, sea ice, physical oceanography, polynyas, primary productivity, climate effects and variability), forage species (silverfish, krill), mesopredators (toothfish, seals, penguins, whales), benthos, pollution and wildlife health (see Appendix A). The workshop goals were to identify, collate, assess, and synthesize research conducted by U.S. researchers in the Ross Sea since 2010, and seen to be relevant to the goals of the MPA (defined in CCAMLR Conservation Measure 91-05). This was done via participants’ summary presentations of research in their areas of expertise (see Appendix A) and gathering all published U.S. Ross Sea region research since 2010 (see Appendix C), as well as currently funded research (see Appendix D). Further goals were to discuss and identify gaps in RSRMPA research and monitoring, determine ways to fill those gaps, elucidate critical uncertainties regarding the Ross Sea ecosystem structure and dynamics (see Appendix B), and develop ideas for coordination between ongoing and future research in the RSRMPA. Below we provide a summary of ongoing and, since 2010, peer-reviewed U.S. Ross Sea research of relevance to meeting the objectives and possible future updates of the RSRMPA and RMP. We also note critical uncertainties, data gaps and actions the workshop participants consider necessary to address them.

This document summarizes several papers submitted to the Grym e-group and other working groups during 2020 and 2021 on proportional recruitment (R.mean, R.var inputs to the Grym: the square of SD of proportional recruitment is the 'R.var' input) from research surveys and the fishery; and biomass variability (B0logsd input to Grym) from research surveys in Subarea 48. Two different length ranges, <36 mm and <40 mm, are used to define 'recruits' in the proportional recruitment comparisons. Proportional recruitments calculated from the fishery samples were generally lower (mean range 0.083 to 0.405, SD range 0.109 to 0.213) than the means and standard deviations from the survey data (mean range 0.174 to 0.579, SD range 0.274 to 0.412) for the two length values used to define recruits. This may be the result of the fishery targeting specific size ranges instead of random sampling of the annual size distributions for krill. Using the AMLR data aggregated over all areas and years, proportional recruitment mean and standard deviation were 0.219 and 0.320, respectively, if krill < 36 mm are defined as recruits, and 0.303 and 0.358, respectively, if krill < 40mm are defined as recruits. The mean of the annual CVs for Subarea 48.1 was 0.399, for a mean B0logsd of 0.384. The mean annual CV for Subarea 48.3 was 0.373, for a mean B0logsd of 0.361. Biomass CVs for Subareas 48.1 and 48.3 combined ranged from 0.086 to 1.15. B0logsd values for the combined Subareas ranged from 0.086 to 0.918 with a midpoint of 0.502.

Information on marine predator at-sea distributions is a key component of spatial management frameworks that aim to identify regions important for conservation. Tracking data from seabirds have been widely used to define priority areas for conservation, but such data are often restricted to the breeding population. This also applies to penguins in Antarctica, where identification of important habitat for nonbreeders has received limited attention. The foraging ranges of breeding penguins are constrained to near-shore areas by the high energy needs of chicks at the colony. Conversely, nonbreeding adults are expected to have larger foraging distributions, which may increase their conspecific interactions with birds from neighboring colonies and their vulnerability to threats distant from the breeding colony. Here, we study the movement behavior of nonbreeding Adélie penguins tracked during the 2016/17 breeding season at King George Island (Isla 25 de Mayo) in the South Shetland Islands, Antarctica. We quantify how nonbreeding penguins’ moment behavior varies in relation to environmental conditions and assess the extent of spatial overlap in the foraging ranges of nonbreeders and breeders, which were tracked over several years. The utilization distributions of breeders and nonbreeders overlapped in the central Bransfield Strait. Habitat segregation was greater during the crèche stage of the breeding season compared to incubation and brood, because chick provisioning still constrained the foraging range of breeders while nonbreeders commenced pre-molt foraging trips into the Weddell Sea. Nonbreeders increased their prey search and area-restricted foraging behavior in areas where sea surface temperatures were lower, sea-ice concentration were higher, and over shallower bathymetry nearer the coastline of the Antarctic Peninsula. Differences in the at-sea spatial distribution of nonbreeding and breeding penguins highlight the need to account for different life-history stages when characterizing habitat use of marine predator populations. This is particularly important for “sentinel” species monitored as part of marine conservation and ecosystem-based fisheries management strategies.

The timing of breeding is an important aspect of a species’ realised niche, a method of avoiding competition and a key determinant of breeding success. The flexibility of these strategies may structure community assemblages, particularly in highly seasonal environments such as the Polar Regions. Flexibility in timing likely determines the adaptability of species to rapid, anthropogenic ecological change. Variance in a species’ phenology over time and across locations is an important source of information, but phenology is only rarely recorded at appropriate spatial scales due to the difficulty of monitoring. Using a network of time-lapse photographic cameras to monitor a large number of colonies of three Pygoscelid species of penguins, we show that two species (Adélie and Chinstrap) breed earlier in warmer years, both at the individual colony and species levels. Both temperature-sensitive species have shown a population decline over the roughly 10 years of our study in the Antarctic Peninsula, while Gentoo penguins (temperature insensitive) have stable or increasing populations, particularly at the Southern edge of their range. Latitude was an important determinant of the start of breeding across the same region and temperature-related breeding in Adélie and Gentoo, but not Chinstrap penguins (which have a narrower range than the other two). The sensitivity to temperature in Adélie and Chinstrap penguins is greater than previously reported. The phenological responses to temperature differed according to latitude, showing greater sensitivity to temperature at warmer, lower latitudes. Our results demonstrate that the flexibility of reproductive strategies within as well as between closely related species needs to be considered as a landscape of outcomes with some adaptation to local conditions. This study offers a starting point to understanding whether polar animals can adapt to rapid change or whether elasticity is indicative of increasing stress given the two species showing the most adaptation to changing temperatures are declining in the study area.

In this paper, we report recent changes in the spatial extent of the Pine Island Glacier. The 22% reduction in areal extent means that the newly exposed marine area has been classified as a Stage 1 Special Area for Scientific Study (SASS) in accordance with Conservation Measure 24-04.

This paper provides additional information to that included in COMM CIRC 21/76, allowing WG-EMM opportunity to comment.

As the most abundant penguin species, the diet of Adélie penguin, Pygoscelis adeliae, would be one of the most important indicators for the ecosystem conditions where they inhabit. The diet of seven Adélie penguin populations in the Ross Sea was studied using both metabarcoding and quantitative PCR (qPCR) analyses. 18Sv9 and miniFish primers provided the overall diet compositions and accurate fish species names, respectively. Based on the metabarcoding analysis, main prey items for Adélie penguin were notothenioid fish, Euphausia superba, and Euphausia crystallorophias varies from small fishes. Among the notothenioid fish, three species, including Pleuragramma antarctica, Pagothenia borchgrevinki, and Trematomus spp. were most abundant. qPCR analysis showed a significant geographical difference in the ratio between krill and notothenioids. Populations inhabiting inbound parts of Ross Sea (Edmonson Point and Inexpressible island) showed higher proportions of fish taxa without E. superba, while the other five populations exhibited a higher krill ratio to fish taxa with two krill. The ratio of krill to fish taxa was highly variable for three-year of study and showed annual synchronous patterns in observed populations, suggesting the long-term study for the penguin’s diet should be conducted to understand the relationship between the populations of Adélie penguin and their marine ecosystem in the Ross Sea.

To identify the dietary composition and characteristics of both Adélie (Pygoscelis adeliae) and emperor penguin (Aptenodytes forsteri) at four breeding sites, we performed stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis of down of penguin chicks. Adélie penguin chicks at Cape Hallett mostly fed on Antarctic krill (Eupausia superba; 65.5±3.5%) reflecting the prevalence of that species near Cape Hallett, and no significant differences were noted between 2017 and 2018. However Adélie penguin chicks at Inexpressible Island located near Terra Nova Bay fed on both Antarctic silverfish (Pleuragramma antarctica; 42.5%) and ice krill (Euphausia crystallorophias; 47%) reflecting the high biomass observed in Terra Nova Bay. On the other hand, no significant difference was noted between at both breeding sites of the emperor penguin. Emperor penguin chicks predominantly fed on Antarctic silverfish (74.5±2.1%) at the breeding sites (Cape Washington and Coulman Island), suggesting that diet preference represents the main factor for emperor penguin foraging. In contrast, the diet of Adélie penguin reflected presumed regional differences in prey prevalence as inferred from available survey data.

Krill play a crucial role in the transfer of energy in the marine food web, connecting primary producers and the upper trophic levels in the Terra Nova Bay polynya (TNBP), which is part of the Ross Sea marine protected area. Despite the substantial ecological importance of krill, there are few studies on their distribution and abundance in the TNBP. An acoustic survey was conducted on 7–14 January 2019 in the TNBP, Ross Sea, using a Simrad EK60 echosounder (38 and 120 kHz) aboard the icebreaker RV Araon. The most commonly used range of the difference of the mean volume backscattering strength (MVBS) (2–16 dB) was applied to distinguish krill. The acoustic data (120 kHz) were extracted to examine the krill distribution characteristics. The study area was divided into low-value areas and high-value areas based on the third quartile of the nautical area scattering coefficient. The results showed that the krill aggregations were distributed in three layers at depths of 0–30 m, 70–110 m, and 270–300 m. The interpolated environmental parameters associated with the backscattering strength were compared. High-value areas of krill coincided with relatively low temperature, low salinity, and high chlorophyll, although very weak correlations were found. The primary goal of this study was to understand the vertical and horizontal distributions of krill acoustic biomass and to relate the observed patterns to the dominant environmental conditions.

Southern Ocean marine ecosystems are highly vulnerable to climate-driven change, the impacts of which must be factored into conservation and management. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is aware of the urgent need to develop climate-responsive options within its ecosystem approach to management. However, limited capacity as well as political differences have meant that little progress has been made. Strengthening scientific information flow to inform CCAMLR’s decision-making on climate change may help to remove some of these barriers. On this basis, this study encourages the utilisation of outputs from the United Nations’ Intergovernmental Panel on Climate Change (IPCC). The IPCC’s 2019 Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) constitutes the most rigorous and up-todate assessment of how oceans and the cryosphere are changing, how they are projected to change, and the consequences of those changes, together with a range of response options. To assist CCAMLR to focus on what is most useful from this extensive global report, SROCC findings that have specific relevance to the management of Southern Ocean ecosystems are extracted and summarised here. These findings are translated into recommendations to CCAMLR, emphasising the need to reduce and manage the risks that climate change presents to harvested species and the wider ecosystem of which they are part. Improved linkages between IPCC, CCAMLR and other relevant bodies may help overcome existing impediments to progress, enabling climate change to become fully integrated into CCAMLR’s policy and decision-making.

Recommendations.

CCAMLR is encouraged to continue working towards including climate change considerations in developing its management procedures, and to accelerate the pace of this work to ensure that management is responsive to the effects of change, thereby reducing the risks of additional negative ecosystem impacts. To enhance the scientific foundation for decision-making with specific relevance to climate change, it is recommended that CCAMLR:

1. Assesses the risks climate change presents to its objectives using available information sources:

• Improves mechanisms to coordinate and undertake targeted activities in support of identifying and integrating relevant scientific research outputs on climate change into the work of the Scientific Committee and its Working Groups. • Invites contributions from external experts to ensure access to additional relevant expertise as appropriate. • Further develops mechanisms to ensure that CCAMLR is well informed about climate change research, particularly as the UN IPCC process continues to develop relevant outputs, including AR6 and all subsequent reports. This could involve the establishment of a standing Working Group on Climate Change that reports directly to the Scientific Committee. • Encourages input by its Members to the IPCC process as authors and reviewers, as well as through contributions to the published literature.

2. Identifies the most important risks and aims to understand, reduce and manage these risks:

• Encourages research focused on the continued conservation of Southern Ocean ecosystems in a changing climate by facilitating relevant data collection and responding appropriately to relevant findings. • Actively engages with SCAR, SOOS, ICED and other relevant bodies to develop priorities for scientific research. • Actively engages with organisations or others that manage vessels or assets that might increase opportunities for collection of relevant information, e.g., International Association of Antarctica Tour Operators (IAATO) and Association of Responsible Krill harvesting companies (ARK). • Actively engages with diverse stakeholders to facilitate knowledge-exchange and consider stakeholder values in decision-making processes related to climate change and ecosystem based management.

3. Ensures timely responses to information about these risks, including what action will be taken:

• Develops a work programme with the specific aim of ensuring that the management of all CCAMLR managed fisheries incorporates planning and adaptation pathways that include short-, medium- and longer-term actions to minimise climate change impacts on harvested species and the ecosystem.