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.
Abstract:
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.
SC-CAMLR-40 will take place from 11 to 15 October 2021 online using Interprefy with captions and interpretation. The meeting times will be 21:00–01:40 UTC with a 40-minute break from 23:00 UTC. The preliminary schedule is given below.
Note that to make the meeting easier to follow due to its virtual format, it is proposed to simplify the sequence that items are taken as shown. In order that the report may be prepared in all languages prior to adoption, only a few items will be addressed on Thursday 14 October and the Committee will halt its meeting at 23:00 UTC on that day.
In the second decade of February 2021, the Ukrainian longliner CALIPSO performed the research survey with the bottom longline in the northwestern part of the Weddell Sea (statistical subarea 48.1). The work was carried out in accordance with the research plan SC-CAMLR-39/BG/08. Ukraine went on the operations with deep-sea video camera to get the video data which was started on February 2020.
During the survey at two longline stations in the Research block 48.1_2, a set of equipment for underwater video recording was attached to the fishing gear - underwater video recording system (referred to as UVS). In this way one 4.5 hours video footages were successfully recorded.
Understanding the spatial and temporal distributions of fishes and other Antarctic ecosystem components is critical criteria of the conservation and ecosystem management. Here, we report on continuing a non-extractive method for the study of benthic wildlife, based on UVS.
Together with the video recording, oceanological parameters (depth, temperature and salinity) were also recorded with the DST CTD.
Abstract:
Spatial scale is the common ground of all of the three components (Biomass estimation, stock assessment and risk assessment) for the new krill management strategy. The pros and cons of the potential choices of biomass estimate at various spatial scales were discussed to facilitate the deliberation on Krill Stock Assessment at the WG-SAM-2021 meeting. Considerations were also given on the spatial scale that is appropriate both for acoustic biomass estimation and stock assessment, and on the pragmatic approach to implement the new krill management strategy in an efficient manner. Discussions were focused on the work in Subarea 48.1, but some of these considerations may also be applicable in other Subareas.
Abstract:
CCAMLR has now endorsed a new strategy for the management of Antarctic krill Euphausia superba. This combines outputs from a (i) Generalised Yield Model, (ii) updated krill biomass estimate, and (iii) a risk assessment, to identify catch limits and their spatial distribution for the krill fishery so that harvesting remains precautionary. The risk assessment can be used to identify how to spread the catch in order to minimise risks to krill dependent predators and to juvenile krill. The framework combines three components: localised risk to predators, localised risk to krill and desirability to the fishery. Localised risk to predators relates to the potential for interference by the fishery on predator foraging performance. Predation pressure (consumption of krill as a proportion of biomass of krill) is used as an index of predator risk. Localised risk to krill includes areas dominated by juvenile krill. The desirability to the fishery is a measure of the relative importance of each area to the fishery.
In this paper we report on the ongoing development of the data layers necessary to implement the risk assessment in Subareas 48.2 and 48.3.
Abstract:
The Antarctic Peninsula is one of the most rapidly warming regions on earth, and it is likely that the abundance and distribution of marine predators will change as a result.Procellariiform seabirds are highly mobile predators, which target specific habitat characteristics associated with underlying distributions of prey and areas of increased prey availability. We use ship surveys and hurdle models, to estimate the summer distribution and relative density of 11 seabird species within the northern Antarctic Peninsula marine ecosystem. Models differed among species; however, sea surface temperature and depth were frequently associated with seabird occurrence and had the greatest explanatory power across many species. Null models based on observation data were better at predicting seabird density than models that included environmental covariates. This suggests that the main driver of distribution patterns is the broad-scale habitat features, and fine-scale aggregations within these ranges are harder to predict. Our seabird distribution models reflect known habitat associations, species hotspots, and community organization relative to oceanic and coastal marine processes. Application of species distribution models will benefit the assessments of critical habitat and potential responses to climate change and anthropogenic disturbance, which will provide insight into how species may change in polar ecosystems.
Abstract:
Ecosystem dynamics at the north-west Antarctic Peninsula are driven by complex interactions between physical and biological processes. For example, baleen whale populations are recovering from commercial harvesting against the backdrop of rapid climate change, including reduced sea-ice extent and changing ecosystem composition. Concurrently, the commercial demand for Antarctic krill is increasing, with the potential to increase the likelihood for competition with and between krill predators. However, understanding of the ecology, abundance, and spatial distribution of many krill predators is often limited, outdated, or at spatial scales that do not match those desired for effective fisheries management. We update current knowledge of predator dependence on krill resources by integrating recent telemetry-based data, at-sea observational surveys, regional estimates of predator abundance, and physiological data to estimate the spatial distribution of krill consumption during the austral summer by three species of Pygoscelis penguin, 11 species of flying seabirds, and one species of baleen whale (humpback whale, Megaptera novaeangliae). Our models show that the majority of important areas for krill-predator foraging are close to penguin breeding colonies in coastal areas where humpback whales also regularly feed. We show that krill consumption is highly variable across the region, and often concentrated at fine spatial scales, emphasising the need for management of the local krill fishery at relevant temporal and spatial scales. We highlight that despite less than comprehensive data, cetaceans are likely to consume a significant proportion of the krill consumed by natural predators, but are not currently considered directly in the management of the krill fishery. If management of the krill fishery is to remain precautionary and operate in a way that minimises the risks to krill predator populations, it is necessary to include up-to-date and precise abundance and consumption estimates for seals, fin-fish, squid, and other baleen whale species not currently considered.
Abstract:
Antarctic krill are an important component of the Antarctic marine ecosystem, providing a key food source for many marine predator species. Additionally, krill are the target of the largest commercial fishery in the Southern Ocean, for which annual catches have been increasing in recent years. The krill fishery is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which has recently endorsed a new management framework that requires information about the spatial distribution and biomass of krill. Here, we model the seasonal (summer and winter) spatial habitat use of krill across the northern Antarctic Peninsula region, an area important to the commercial fishery. Using krill density estimates obtained from historical acoustic surveys and a GAMM framework, we model habitat properties associated with high krill biomass. During summer, krill density is elevated around Elephant Island and to the north of the South Shetland Islands, and our models show associations with the shelf break, increased sea-surface temperature, moderate chlorophyll-a concentration and increased salinity. During winter, krill density is elevated in the nearshore waters of the South Shetland Islands, and our models show associations with shallow waters with low sea-ice concentration, medium sea level anomaly, and medium current speed. Our models predict temporal averages of the distribution and density of krill, which can be used to aid the development of CCAMLR’s revised ecosystem approach to fisheries management in this region. We emphasise that our models provide descriptors of habitat characteristics, and do not necessarily identify key drivers of krill distribution. However, our models do have the potential to help in the spatial and temporal design and placement of future acoustic surveys that would preclude the future need for modelled extrapolations. We highlight that the ecosystem approach to fisheries management of krill critically depends upon such field observations at relevant spatial and temporal scales.