CCAMLR has endorsed the use of the Risk Assessment framework to apportion the krill catch limits in order to minimise the risk of the fishery to krill dependent predators. We plan to apply the risk assessment framework across Subarea 48.1 at various spatial and temporal scales, in order to identify the most appropriate way to spread the catch from the fishery. The risk assessment framework requires data layers describing the distribution and krill consumption by krill-dependent predators. This paper describes the progress to-date in developing the data layers to input into the risk assessment framework.

CCAMLR has endorsed the use of the Risk Assessment framework to apportion the krill catch limits in order to minimise the risk of the fishery to krill dependent predators. We plan to apply the risk assessment framework across Subarea 48.1 at various spatial and temporal scales, in order to identify the most appropriate way to spread catch limits for the krill fishery. The risk assessment framework requires data layers describing the distribution and krill consumption by krill-dependent predators. This paper describes the analysis of cetacean observations from at-sea surveys, to estimate the abundance, distribution and consumption of krill by humpback whales, to be input into the risk assessment framework. 

We discuss a number of ecological issues in relation to CCAMLR’s aspiration for managing the krill fishery at small temporal and spatial scales. We highlight that the devil is in the detail, and a lot of detail is potentially necessary for managing at these smaller scales. Much of this detail is currently lacking, or only partial; consequently, we highlight an alternative approach, closed coastal areas.

Closed coastal areas potentially protect near-shore krill-dependent predators from the impacts of fishing, augmenting CCAMLR’s existing large-scale management framework. Seasonal, or year round closed coastal buffers will alter the potential levels of catch displacement, and therefore highlights the need for coupled research to ensure fishery displacement does not become too concentrated in other vulnerable habitats.

A body of research will be fundamental to understanding how to move beyond the current harvest levels, including the implementation of regular acoustic surveys at different times of year to better inform both ecological understanding and harvesting regimes. This is important as we demonstrate that krill demand from a range of predators in near-shore coastal habitats may only be met through oceanographic flow and krill movement. Krill flux and krill behaviour remains key to increased understanding.

Repeated acoustic assessments, ongoing research, couple with closed coastal areas has the potential to lead to a new management dynamic.

The South Orkney Islands region is a key location for understanding the distribution of Antarctic krill in CCAMLR Area 48. The local krill populations support krill-dependent higher predators and krill fisheries, and the regional oceanographic circulation provides connections between the Antarctic Peninsula, the South Orkney Islands and the central Scotia Sea and South Georgia. Furthermore, the South Orkney Islands lie in the seasonal sea ice zone. Sea ice is an important overwintering habitat for Antarctic krill, and how krill use the sea ice habitat can impact their distribution. To better determine the local ecosystem dynamics in this key region requires greater understanding of the extent to which krill - sea ice interactions influence the local distribution and retention of krill. Here we present results from a modelling study that suggest that the use of the sea ice habitat by krill affects the regional and local transport pathways to and in the South Orkneys region, and the residence time of krill on the South Orkney plateau. We found that including sea ice-associated behaviour of krill in the model provides additional source regions for the South Orkney Islands krill population than when krill are advected only with ocean currents, permitting episodic transport from much of the northern Antarctic Peninsula within a 9 month time period. Sea ice-associated behaviour also reduces retention time on the South Orkney plateau, with sea ice transferring material off the shelf rapidly. Variability in the source regions and retention timescales arises from variability in the regional and local sea ice dynamics. Our results demonstrate the importance of understanding the behaviour of krill under sea ice, including how the behaviour changes in response to different sea ice conditions and as krill mature, to better resolve the connectivity of krill populations in CCAMLR Area 48.

High-latitude ecosystems are among the fastest warming on the planet. Polar species may be sensitive to warming and ice loss, but data are scarce and evidence is conflicting. Here, we show that, within their main population centre in the southwest Atlantic sector, the distribution of Euphausia superba (hereafter, ‘krill’) has contracted southward over the past 90 years. Near their northern limit, numerical densities have declined sharply and the population has become more concentrated towards the Antarctic shelves. A concomitant increase in mean body length reflects reduced recruitment of juvenile krill. We found evidence for environmental controls on recruitment, including a reduced density of juveniles following positive anomalies of the Southern Annular Mode. Such anomalies are associated with warm, windy and cloudy weather and reduced sea ice, all of which may hinder egg production and the survival of larval krill. However, the total post-larval density has declined less steeply than the density of recruits, suggesting that survival rates of older krill have increased. The changing distribution is already perturbing the krill-centred food web and may affect biogeochemical cycling. Rapid climate change, with associated nonlinear adjustments in the roles of keystone species, poses challenges for the management of valuable polar ecosystems.

The biological carbon pump drives a flux of particulate organic carbon (POC) through the ocean and affects atmospheric levels of carbon dioxide. Short term, episodic flux events are hard to capture with current observational techniques and may thus be underrepresented in POC flux estimates. We model the potential hidden flux of POC originating from Antarctic krill, whose swarming behaviour could result in a major conduit of carbon to depth through their rapid exploitation of phytoplankton blooms and bulk egestion of rapidly sinking faecal pellets (FPs). Our model results suggest a seasonal krill FP export flux of 0.039 GT C across the Southern Ocean marginal ice zone, corresponding to 17–61% (mean 35%) of current satellite-derived export estimates for this zone. The magnitude of our conservatively estimated flux highlights the important role of large, swarming macrozooplankton in POC export and, the need to incorporate such processes more mechanistically to improve model projections.

Antarctic krill, Euphausia superba, have a circumpolar distribution but are concentrated within the south-west Atlantic sector, where they support a unique food web and a commercial fishery. Within this sector, our first goal was to produce quantitative distribution maps of all six ontogenetic life stages of krill (eggs, nauplii plus metanauplii, calyptopes, furcilia, juveniles, and adults), based on a compilation of all available post 1970s data. Using these maps, we then examined firstly whether “hotspots” of egg production and early stage nursery occurred, and secondly whether the available habitat was partitioned between the successive life stages during the austral summer and autumn, when krill densities can be high. To address these questions, we compiled larval krill density records and extracted data spanning 41 years (1976-2016) from the existing KRILLBASE-abundance and KRILLBASE-length-frequency databases. Although adult males and females of spawning age were widely distributed, the distribution of eggs, nauplii and metanauplii indicates that spawning is most intense over the shelf and shelf slope. This contrasts with the distributions of calyptope and furcilia larvae, which were concentrated further offshore, mainly in the Southern Scotia Sea. Juveniles, however, were strongly concentrated over shelves along the Scotia Arc. Simple environmental analyses based on water depth and mean water temperature suggest that krill associate with different habitats over the course of their life cycle. From the early to late part of the austral season, juvenile distribution moves from ocean to shelf, opposite in direction to that for adults. Such habitat partitioning may reduce intraspecific competition for food, which has been suggested to occur when densities are 39 exceptionally high during years of strong recruitment. It also prevents any potential cannibalism by adults on younger stages. Understanding the location of krill spawning and juvenile development in relation to potentially overlapping fishing activities is needed to protect the health of the south-west Atlantic sector ecosystem.

ICED is an international multidisciplinary programme undertaking integrated circumpolar analyses to improve understanding of Southern Ocean change, the implications for ecosystems and for management. Through ongoing engagement between ICED, CCAMLR scientists and the CCAMLR Secretariat, there is increasing mutual understanding of the key areas of ICED science and associated activities that are also of interest to CCAMLR. The 2018 ICED Projections Workshop, undertaken in collaboration with CCAMLR, provided an initial, mainly qualitative, assessment of the potential impacts of climate change on krill, their predators and the fishery in Area 48, and considered the implications for including climate change in decision making for conservation and management. This paper highlights recent ICED research and activities on Southern Ocean ecosystems and change, focusing on areas of interest to CCAMLR and joint ICED-CCAMLR activities, and suggests ways to continue to strengthen the links between ICED and CCAMLR. We encourage CCAMLR involvement in relevant ICED activities to jointly identify, prioritise and address key scientific issue with respect to the management of Southern Ocean ecosystems in the face of change.

A proposal for a new Antarctic Specially Protected Area, Rosenthal Islands, Anvers Island, Palmer Archipelago, has been submitted by the United States for consideration at the 2019 Meeting of the Antarctic Treaty Consultative Meeting - Committee for Environmental Protection (ATCM XLII - CEP XXII, 1 – 11 July). In order to fulfill the requirements of ATCM Decision 9 (2005), the management plan is submitted for consideration by WG-EMM.

This document presents a prototype of Fishery Report built using R Markdown. Documents produced in R Markdown may be exported into pdf format (this paper) as well as html pages (available on the SAM meeting server). The 2018 Working Group on Fish Stock Assessment welcomed the Secretariat’s intent to transform the way Fishery Reports will be published, into standardised and automated webpages (WG-FSA-18 paragraph 2.30).