CCAMLR

The northern regions of the Scotia Sea demonstrate notable variability in environmental conditions, particularly in the location of the Polar Front. This has a strong influence on patterns of productivity and distribution of plankton, with implications to higher trophic levels, including harvested species. The long-term impact of environmental variability on plankton species composition and abundance has been monitored through conducting a series of Continuous Plankton Recorder (CPR) tows in the South Atlantic Ocean since 2005. The tows were carried out as a collaboration between the British Antarctic Survey (BAS) and the Sir Alister Hardy Foundation for Ocean Science (SAHFOS). This report documents the series of tows that have been carried out to date, which comprises more than 2000 samples from 78 successful tows. Of these, 715 samples have been analysed.  A total of 245 taxa have been recorded, with abundance being far more variable than species composition within and between tows.  In general, phytoplankton were most abundant in the tows taken in November and December but sharp declines occur by April. Diatoms dominated the phytoplankton together with coccolithophores and silicoflagellates. The most commonly recorded copepod was Calanus simillimus, while Thysanoessa spp. was the most abundant euphausiid. An analysis considering the relationship between satellite-derived dynamic height (from which frontal positions may be approximated) and abundance of biomass-dominant species indicated varying affinities, implying that major faunal shifts will accompany any changes to frontal locations in this region.

Increased awareness about the present status of marine systems, including those where fisheries target the prey of natural predators, has led to recommendations about how information on the status of marine predators might be used to inform ecosystem-based management approaches. In the Antarctic, sustained ecological research has generated long-term data on the performance of marine predators, coupled with data that describe the density of their principal prey, Antarctic krill. Here we explore some of the longest time series of such data yet available, using records that were closely matched with consistent ecological time periods. Our results show that: (i) at the larger scale, some predator variables are correlated across sites and they therefore probably reflect common regional ecological conditions; (ii) at smaller scales, other variables depend upon local biological conditions, requiring that managers must evaluate the applicable scale of these predator indices if they are to be used in management decisions; (iii) variability in the krill population is evident at different spatial and temporal scales, some of which is important for predators, indeed when krill density is low, spatial variability and patchiness is probably a more important determinant of foraging success than density per se; (iv) previously documented relationships between predators and krill density are not apparent, suggesting that correlative relationships may break down as data series change in duration. We note that relationships that describe critical density thresholds for prey might not provide adequate management information, particularly at low krill densities. We suggest that a programme of work is needed to better characterise predator requirements, if ecosystem-based approaches are to be reliably implemented.

In 2015 the European Union proposed a draft Conservation Measure (CM) with the aim of promoting and facilitating scientific research in newly exposed marine areas following ice shelf retreat or collapse around the Antarctic Peninsula (CCAMLR-XXXIV/21). The proposed CM would establish Special Areas for Scientific Study in such areas, with a designated 10-year study period during which time there would be a moratorium on all fishing activities, except for scientific research fishing activities undertaken in accordance with Conservation Measure 24-01.

This proposal was developed following a recommendation by the Antarctic Treaty Meeting of Experts on Climate Change in 2010. The scientific basis of the proposal received broad support from the Scientific Committee in 2015 (SC-CAMLR-XXXIV, paragraphs 8.14 to 8.22), and also in 2012 (SC-CAMLR-XXXI, paragraphs 5.42 and 5.56). A summary of the scientific background is attached for information as Appendix 1. The proposed Special Areas for Scientific Study were agreed by most Members to be an appropriate and practicable response to an important issue. However, a number of points for clarification were raised by the Scientific Committee and the Commission.

In this paper, we present some clarifications and options for the proposed mechanism by which Special Areas for Scientific Study could be established, taking into account the points raised by the Scientific Committee and the Commission during their discussions in 2015. We would welcome the views of WG-EMM-16. Based on advice received from the Working Group, a revised Conservation Measure will be developed and submitted to the Commission in 2016.

This paper examines temporal changes in distribution and sighting density indices of krill-eater baleen whales in Subareas 48.1 and 48.2. This paper was prepared in response to a suggestion in EMM-15 that an analysis of historical cetacean surveys in IWC Area II could provide a context for at-sea observations of cetaceans. Sighting data examined in this study were obtained during a series of Antarctic sighting cruises for whale assessment purposes organized by the International Whaling Commission Scientific Committee (IWC SC) in the context of the research programs ‘International Decades of Cetacean Research’ (IDCR) and Southern Ocean Whale and Ecosystem Research (SOWER), which were organized into three circumpolar surveys (CPI, II and III) between 1978/79 and 2009/10 austral summer seasons. CPI, CPII and CPIII data in Subarea 48.1 corresponded to years 1982/83, 1989/90 and 1993/94+1999/00, respectively while that in Subarea 48.2 those corresponded to years 1981/82, 1986/87 and 1997/98, respectively. The density indices in both subareas suggested that humpback and fin whales were more frequently observed in CPIII than in CPII while that Antarctic minke whale showed an inverse trend. These observations are consistent with abundance estimates trend in humpback and Antarctic minke whales. Two issues are of importance for management of krill under the FBM. The first is the development of the stock abundance of whales in relevant subareas for krill management, and the second is on the concentration of whales in the krill fishing/top predators feeding areas, and the impact on land-based predators.

Integrating Climate and Ecosystem Dynamics in the Southern Ocean (ICED) is a regional programme of the Integrated Marine Biogeochemistry and Ecosystem Research (IMBER) Programme and is closely linked with Scientific Committee on Antarctic Research (SCAR). ICED is undertaking integrated circumpolar analyses to improve our understanding of change and the implications for Southern Ocean ecosystems and for management of human impacts. A diverse range of multidisciplinary research is underway through core activities such as historical data rescue and synthesis, fieldwork, and modelling.  Considerable progress has been made in understanding the structure and functioning of ecosystems, modelling species and food webs, and with qualitative assessments of change.  ICED’s current major focus is to build on this work to more comprehensively assess (and where possible quantify) key impacts of change on Southern Ocean ecosystems. This will be achieved through the analysis and integration of available data together with development of models, scenarios and projections. These activities and their outputs will provide valuable information for ecosystem-based management in the region.  The ICED Scientific Steering Committee propose that it is now appropriate for ICED and CCAMLR scientists to work more closely together to jointly identify and address a number of key scientific issues which are of interest to both groups.

Target identification remains a challenge for acoustic surveys of marine fauna. Antarctic krill, Euphausia superba, are typically identified through a combination of expert scrutiny of echograms and analysis of differences in mean volume backscattering strengths (S_V; dB re 1 m^-1) measured at two or more echosounder frequencies. For commonly used frequencies, however, the differences for krill are similar to those for many co-occurring fish species that do not possess swim bladders. At South Georgia, South Atlantic, one species in particular, mackerel icefish, Champsocephalus gunnari, forms pelagic aggregations, which can be difficult to distinguish acoustically from large krill layers. Mackerel icefish are currently surveyed using bottom-trawls, but the resultant estimates of abundance may be biased because of the species’ semi-pelagic distribution. An acoustic estimate of the pelagic component of the population could indicate the magnitude of this bias, but first a reliable target identification method is required. To address this, random forests were generated using acoustic and net sample data collected during surveys. The final random forest classified krill, icefish, and mixed aggregations of weak scattering fish species with an overall estimated accuracy of 95%. Minimum S_V, mean aggregation depth (m), mean distance from the seabed (m) and geographic positional data were most important to the accuracy of the random forest. Time-of-day and the difference between S_V at 120 kHz (S_{V 120}) and that at 38 kHz (S_{V 38}) was also important. The random forest classification resulted in significantly higher estimates of backscatter apportioned to krill when compared to widely applied identification methods based on fixed and variable ranges of S_{V 120} - S_{V 38.} These results suggest that krill density is underestimated when those methods are used for target identification. Random forests are an objective means for target identification, and could facilitate the inclusion of acoustic data in the assessment of mackerel icefish.

• First attempt to systematically identify marine IBAs in the Antarctic

• Assessed all available penguin tracking data for Subarea 48.1 (Antarctic Peninsula, and South Shetland Islands) and Subarea 48.2 (South Orkney Islands)

• Developed new protocols for determining candidate IBAs based on penguin tracking data

• Identified 6 candidate marine Important Bird and Biodiversity Areas (IBAs)

• Outlines future work for developing a more complete IBA network

This paper is a revised version of WG-EMM-15/28, which uses a question and answer format to explain the management of the Antarctic krill (Euphausia superba) fishery in the subareas 48.1 to 48.4, and current knowledge about the state of the regional krill stock. The revisions provide a new, precautionary assessment of exploitation rate in this fishery. The effective regional catch limit (or “trigger level”), established in 1991, is 0.62 million tonnes year^-1, equivalent to ~1% of the regional biomass estimated in 2000. Additional subarea catch limits were established in 2009. There is some evidence for a decline in the abundance of krill in the 1980s, but no evidence of further decline over more recent decades. Biomass indices from local monitoring programmes established in the 1990s and 2000s also show no evidence of a further decline. Extrapolation from these local monitoring programmes provides conservative estimates of the regional biomass in recent years. This suggests that the trigger level would be equivalent to a long-term exploitation rate (catch divided by biomass) of <7%, which is below the 9.3% level considered precautionary for Antarctic krill. However, the permitted exploitation rate in each subarea, derived from the subarea catch limit, appears to exceed this level in up to 20% of years due to high variability in krill biomass indices. The actual exploitation rate in each subarea has remained <3% because annual catches have been <50% of the regional trigger level since 1991. The subarea catch limits help prevent higher exploitation rates.  The CAMLR Commission also needs to manage the risk of adverse impacts on the ecosystem which might occur as a result of climate change or concentrated fishing in sensitive areas. Frequent assessment of the krill stock will enhance the Commission’s ability to manage these risks. Continuing the local monitoring programmes will provide valuable information on krill variability, but more information is required on how the monitored biomass relates to biomass at the subarea scale. The most effective means to acquire this information is likely to be through the use of fishing vessels to collect data.

This paper briefly describes the rationale and structure of the research cruise that formed a key component of the co-ordinated, multi-national South Orkney Ecosystems Studies focusing on the krill-based ecosystem in the main fishing area in Subarea 48 undertaken in the austral summer of 2015-16. The research cruise consisted of collection of at-sea data on the distribution, abundance and behaviour of krill and its predators across a range of temporal and spatial scales using acoustics, nets and cameras. The research vessel data are linked to complementary studies undertaken from a commercial fishing vessel and field camps on Monroe Island, Powell Island and at Signy where satellite tracking of penguins and fur seals was undertaken. Taken together these data sets and the expected outputs will provide key information on important interactions between krill, krill predators and the commercial fishery that will be an important contribution to developing feedback management strategies.