CCAMLR

Leopard seals are an important Antarctic apex predator that can affect marine ecosystems through local predation. Here we report on the successful use of micro geolocation logging sensor tags to track the movements, and activity, of four leopard seals for trips of between 142-446 days including one individual in two separate years.  Whilst the sample size is small the results represent an advance in our limited knowledge of leopard seals. We show the longest periods of tracking of leopard seals’ migratory behaviour between the pack ice, close to the Antarctic continent, and the sub-Antarctic island of South Georgia. It appears that these tracked animals migrate in a directed manner towards Bird Island and, during their residency, use this as a central place for foraging trips as well as exploiting the local penguin and seal populations. Movements to the South Orkney Islands were also recorded, similar to those observed in other predators in the region including the krill fishery. Analysis of habitat associations, taking into account location errors, indicated the tracked seals had an affinity for shallow shelf water and regions of sea ice. Wet and dry sensors revealed that seals hauled out for between 22 and 31% of the time with maximum of 74 hours and a median of between 9 and 11 hours. The longest period a seal remained in the water was between 13 and 25 days. Fitting GAMMs showed that haul out rates changed throughout the year with the highest values occurring during the summer which has implications for visual surveys. Peak haul out occurred around midday for the months between October and April but was more evenly spread across the day between May and September. The seals’ movements between, and behaviour within, areas important to breeding populations of birds and other seals, coupled with the dynamics of the region’s fisheries, shows an understanding of leopard seal ecology is vital in the management of the Southern Ocean resources.  

Foreword to 14 papers in a themed issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

The Southern Ocean is fundamentally important to the Earth system, influencing global climate, biogeochemical and ecological cycles. Limited observations suggest the Southern Ocean is changing, yet chronic under-sampling makes the causes and consequences of such changes difficult to assess, and limits the effectiveness of any response. A Southern Ocean Observing System (SOOS) is thus being created, to facilitate integration of resources, to enhance data collection and access, and to guide the sustained development of strategic, multidisciplinary science in the Southern Ocean. Here we outline the long-term vision for this system, the gains inherent in its implementation, and how the international community can move towards achieving it.

Recognising that CM 51-07 is scheduled to lapse at the end of the 2020/2021 fishing season, we outline a plan of work to engage with the CCAMLR community to move towards refining the krill risk assessment framework. WG-EMM has previously offered advice about how the risk assessment might be improved for the future. We therefore indicate key areas for community engagement to help develop the next version of the risk assessment framework.

We review reasons why the fishery for Antarctic krill is challenging to manage and consider ways in which management could be improved, whilst responsible and precautionary harvesting continues. We propose an experimental framework to help improve the scientific basis for management. This framework will enhance conservation, and increase ecological understanding by using an experimental approach to fishing, coupled with the use of Krill Reference Areas and Krill Fishing Areas. We use the existing Small Scale Management Units, modified to take into account biological and physical environmental characteristics, as the geographic and spatial basis for a set of differing treatments. We also consider the existing CEMP ecosystem monitoring framework across Subareas 48.1 and 48.2, noting that monitoring is mainly associated with penguin research. We identify a number of treatments based on seasonal, or year round closures, and highlight how enhanced scientific data collection, using existing methods and approaches could be used to enhance ecological understanding of possible impacts (or lack thereof) of krill fishing. We also consider how certain treatments could be used to help disentangle confounding drivers of change, including climate change. We offer this paper as a discussion document, to help further the management of the krill fishery. We welcome comments and suggestions to help improve the concepts and implementation. We also request input upon how the proposed framework could strengthen the development of other conservation measures presently under development.

In this paper we drawn comparison between the existing CCAMLR Ecosystem Monitoring Programme (CEMP) and plans to develop Research and Monitoring Plans for Marine Protected Areas. We recall the outcomes of the CEMP Review in 2003, and as a result highlight the intensity of monitoring required to detect change and to ascribe cause. We therefore propose that CCAMLR build even stronger links with SOOS to ensure relevant data are available. We highlight that a hierarchical approach to monitoring could be employed to detect the first signs of change.

Catch limits for toothfish in research blocks were set for the 2017/18 season using a qualitative analysis of trends in biomass estimated in each research block and a series of simple decision rules developed by WG-FSA-17. The Scientific Committee recommended that the approach be further developed and tested as a matter of priority for WG-SAM-18. We formalised and codified the rules and developed a simulation approach to examine the performance of the trend analysis rules for scenarios with high or low abundance, high or low uncertainty in biomass estimates, and for populations with increasing, stable, or decreasing trends in abundance. The trend analysis rules performed well given the expected inter-annual variability in biomass estimates, and they increased or decreased catch limits as the simulated population increased or decreased in abundance, though with a longer lag when population abundance was increasing. Further evaluations are needed to implement scenarios where populations change in response to catches and to test the overall management approach.

Features of the implementation of the tagging program on vessels of Ukraine CALIPSO, KOREIZ, MARIGOLDS, SIMEIZ are presented.

Based on a recommendation by WG-FSA in 2017 (para. 3.13), this paper presents examples for a set of standard diagnostics including R code to be used for mackerel icefish (Champsocephalus gunnari) stock assessments presented to WG-FSA.

This paper presents a ‘first-step’ proposal for CCAMLR to consider the effects of environmental variability and change on management advice from toothfish assessments. We focus on changes to environmental conditions that are maintained over a number of years, which includes the effects of global climate change. The effects of environmental variability and change on toothfish population dynamics and productivity are largely unknown and are difficult to predict given our current understanding of the Southern Ocean environment and ecosystems. However, we note that existing information from toothfish fisheries can be used to identify changes that have occurred, or changes that may currently be occurring, as a consequence of environmental variability and change, including that due to global climate change.

We note that CCAMLR’s fishery reports may be revised to include a new section on changes in model parameters and productivity assumptions that have been found to have occurred, and that these may be related to the effects of environmental variability and change. We note that causal relationships between observed changes in stock productivity and environmental conditions are not required for this understanding to be useful. We propose that consideration of changes in biological parameters and work to understand the impact of these changes on yield assessment would reduce uncertainty in management advice. The parameters that could be evaluated to for the effects of environmental variability and change would include mean recruitment (ȳ), recruitment variability (σ_R), mean length at age, mean weight at length, natural mortality (m), and maturation ogives. Other factors that may impact assumptions underlying the assessments that could also be considered, including stock distribution (for example, for its impact on tagged fish distribution or research survey interpretation), sex ratio (indicating maturation or other sex specific changes), and the ages or lengths observed in the fishery (indicating changes in vulnerability patterns or mortality). Further, we recommend that methods be developed that can be used to evaluate the importance of observed changes in the toothfish productivity or distribution on resulting advice.