CCAMLR

The embryonic development of Antarctic krill (Euphausia superba) is sensitive to elevated seawater CO₂ levels and successful hatching is impaired at CO₂ levels greater than 1000 μatm. Exposure to elevated CO₂ during the first 3 days of embryonic development significantly retards subsequent development even if the embryos are transferred to seawater with current levels of CO₂. Krill embryos appear more vulnerable to ocean acidification than other pelagic crustaceans such as copepods. pCO₂ in the Southern Ocean are predicted by models to rise to above 1500 μatm in some parts of krill’s depth range by the year 2100 unless emissions are mitigated.  Risk maps, combining modelled hatch rates and the 3-dimensional circumpolar projection of future pCO₂, predict that by 2100 the Weddell Sea and the waters to the east (the Haakon VII Sea) are the highest risk areas for krill embryos.  The entire Southern Ocean south of the Polar Front is predicted to be unsuitable for hatching by the year 2300, which would lead to collapse of the krill population. This is the first report that explores the circumpolar impacts of ocean acidification on krill.

This report describes the work and preliminary results from the fourth annual survey conducted around the South Orkney Islands, using a commercial krill fishing vessel as research platform. The overall purpose is to describe taxonomy of the macrozooplankton community, demography and density of Antarctic krill as well as the occurrence and distribution of krill predators.

Antarctic krill (Euphausia superba) aggregate in various ways depending on a range of factors, from biological (e.g. antipredatory behavior, social interactions and food availability) to physical forcing (e.g. advection and retention). Some areas, often associated with topographical features such as shelf edges and canyons, are considered as hotspots of high importance for regional pelagic ecosystems and also for the krill fishing industry. Despite the importance of such krill hotspots, their dynamics over time with respect to spatial distribution and demographical composition of krill including spawning state is not well described or understood. In the present study, a krill fishing vessel during regular operation was used as a platform for frequent collection of biological data to investigate krill demographic composition and the continuous acquisition of acoustic data for studying their distribution within a 75 km strip on the shelf edge northwest of the South Orkney Islands. The study was carried out towards the end of the reproductive season, during 29 January to 1 March 2009, and during the study, the occurrence of all the sub adult male stages (MIIA1, MIIA2 and MIIA3) decreased. Concurrently, the occurrence of both male adult stages (MIIIA and MIIIB) increased, but at a lower rate. Overall, there was also a gradual decrease from more than 0.8 to less than 0.3 in the proportion of males relative to females. The decrease in subadult males indicates segregation according to demographical composition, and the change in male to female ratio that there might be a flux of krill to/from the hotspot location. There was generally a clear diel vertical migration pattern with deeper and vertically more compact swarms during daytime than night-time. However, there was days with very small differences in distribution between day and night and in general also a huge day-to-day variability in daytime depth distribution. The fishing pattern reflected the fluctuating vertical distribution. It is essential for management purposes to understand the mechanisms behind the distribution and demography patterns described here, and also to obtain quantitative data on krill flux and retention potential, especially if the fishing activity expands in future.

The overall purpose of this study was to estimate the mortality rate of Antarctic krill (Euphausia superba) that escape from the most common mesh size used in the current commercial fishery. The experiment was carried out on the krill fishing grounds off South Orkney Islands (60°35’S, 45°30’W), during January-February 2014. The method applied consisted of a covered trawl codend system for retaining escapees, thereafter kept on the surface in tanks to monitor rates of mortality. Hauling depth and duration as well as handling effects on land including exposure to temperature differences likely influenced on the mortality rates found. A decrease in body length was also found significantly correlated with increased mortality rate. The escape mortality rate from experiment parallels and considered to be closest to a realistic catching process in a 16 mm mesh size, was found to be 1-6%. Krill may be more tolerant to mechanical damage than other taxon due to their durable exoskeletons.

During 18 Ukrainian Antarctic expeditions, from March 31 2013 to April 7 2014, in region Ukrainian Antarctic station "Academic Vernadsky" study of avifauna was conducted. Magellanic Penguin Spheniscus magellanicus was newly recorded for that area. Currently, this finding is the southernmost part of this species.

Acoustic and net sampling of Antarctic Krill and other euphausiids was conducted at 88 stations around the South Shetland Islands during a 30 day cruise between 10 August and 9 September 2013. Abundance and demographic patterns revealed that Antarctic krill were concentrated in the southern Bransfield Strait, and that these krill were approximately 33mm in length, about 10mm larger than found during the 2012 winter survey (Reiss and Jones 2013; WG-EMM 13/40) but similar in size to krill found in the German survey during summer in 2013 (Siegel 2013; WG-EMM 13/24). Large krill (>50mm), although present around Elephant Island, were not abundant in any area, and were also not abundant in the water column between 170 and 650m depth in the Antarctic Circumpolar Current. Sea ice extent and concentration was expansive (north of 60 S around Elephant Island) and the sea ice concentration was mostly more than 50%. Observations of birds and mammals showed that many species were found in southwestern Bransfield Strait, associated with the high concentrations of krill, an area targeted by the krill fishery in recent years. Species of note included Crabeater seals, Antarctic fur seal (sub-Adults), Leopard seal, and Adelie penguins. The high abundance of predators and prey in the Bransfield Strait, where the krill fishery is prosecuted into autumn, suggests that overlap between krill dependent predators and the fishery extends throughout the post reproductive period of many higher predators. Such overlap could impact the overwinter survival of predators if the fishery extracts prey from hotspots during autumn.

In June 2014, the ICED programme, the British Antarctic Survey and WWF co-hosted a two day workshop entitled “Understanding the objectives for krill fishing and conservation in the Scotia Sea and Antarctic Peninsula region” which involved participants from the science, conservation and fishing industry sectors. This report summarises the key initial conclusions and recommendations from the workshop. There is broad cross-sector commitment to maintaining a healthy ecosystem and support for management of the krill fishery that minimises the risk of the fishery negatively impacting ecosystem health. This accord could be strengthened by articulating a clear research and development strategy to support progress in the management of the krill fishery; broadening participation in WG-EMM to include other sectors and areas of expertise; and improving the availability of key information to all sectors.

We report on the first global census of the Adélie Penguin (Pygoscelis adeliae), achieved using a combination of ground counts and satellite imagery, and find a breeding population 53% larger (3.79 million breeding pairs) than the last estimate in 1993. We provide the first abundance estimates for 41 previously unsurveyed colonies, which collectively contain 420,000 breeding pairs, and report on 17 previously unknown colonies. We think 11 of these previously unknown colonies may be recent colonizations. These recent colonizations represent approximately 5% of the increase in known breeding population and provide insight into the ability of these highly philopatric seabirds to colonize new breeding territories. Additionally, we report on thirteen colonies not found in the survey, including eight we conclude have gone extinct. Our global population assessment provides a robust baseline for understanding future changes in abundance and distribution, and finds that Adélie Penguin declines on the Antarctic Peninsula are more than offset by increases in East Antarctica. These results represent a critically-needed contribution to ongoing negotiations regarding the design and implementation of Marine Protected Areas for the Southern Ocean.

We present preliminary analyses of krill fishery catch data covering the period December 2000 to November 2013. We show that fishing vessels in Subareas 48.2 and 48.3 are conservative in their behaviour, targeting fixed geographic locations in most years. In contrast, in Subarea 48.1, fishing locations show considerable variability between years. In Subarea 48.2 ice cover tends to increase rapidly from mid May, often extending to cover the whole core fishing area, forcing the fishery to relocate by late June. Much of the effort relocates to Subarea 48.3, where the shelf and shelf-break fishing areas are normally ice free throughout the winter. In Subarea 48.1 ice cover begins to increase earlier (often in April) but it increases more gradually and rarely covers the whole core fishing area. This often allows fishing to late June and, sometimes, throughout the winter. Overall, the mean catch location in Subarea 48.1 has shifted in recent years with most catch being taken south of the South Shetland Islands since 2008/09 in contrast to earlier years when the mean catch location was always to the north and west of the South Shetlands. We will continue to explore the relationship between catch location and ice dynamics during the inter-sessional period.

This paper, now in press in ICES Journal of Marine Science, presents krill density estimates for a 17 year time series of acoustic surveys of the Western Core Box at South Georgia.  Krill targets were identified in acoustic data using the approved CCAMLR protocol, that is using a multi-frequency identification window and converted to krill density using the Stochastic Distorted-Wave Born Approximation (SDWBA) target strength model. Krill density ranged over several orders of magnitude (0 to 10 000 g m^-2) and its distribution was highly skewed with many zero observations. Within each survey the mean krill density was significantly correlated with the top 7% of the maximum krill densities observed. Hence, only the densest krill swarms detected in any one year drove the mean krill density estimates for the WCB in that year. WCB krill density (µ, mean density for the area) showed several years (1997-8, 2001-2003, 2005-2007) of high values (µ > 30 g m^-2) interspersed with years (1999-2000, 2004, 2009-2010) of low density (µ < 30 g m^-2). This pattern showed three different periods, with fluctuations every 4 to 5 years. Cross correlation analyses of variability in krill density with current and lagged indices of ocean (Sea Surface Temperature, SST) and atmospheric variability (Southern Annular Mode, SAM and El Niño/Southern Oscillation, ENSO) found the highest correlation between krill density and winter sea-surface temperature (August SST) from the preceding year. A quadratic regression (r² = 0.42, P<0.05) provides a potentially valuable index for forecasting change in this ecosystem.

In addition to the paper, we present an additional table (Table 0) which takes the values of krill density from the paper, derives the total krill biomass for the survey area and provides commercial krill catches for SSMUs within subarea 48.3. Note that commercial catches within SGW are very small in comparison to the biomass in the WCB and even total commercial catch in subarea 48.3 is frequently less than 10% of the biomass within the WCB.