CCAMLR

The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) aims to develop a feedback approach to aid Ecosystem Based Management (EBM) of the Antarctic krill fishery in the Southern Ocean. Feedback approaches in fisheries management usually include harvest control rules (HCRs) which are derived from control theory. Model Predictive Control (MPC) optimises control rules based on their predicted performance in a model of the controlled system. Here we use MPC to develop a robust control strategy for a simulation model of a spatially resolved predator-prey system. We identify optimal HCRs based on an objective for the state of the target stock and constraints equivalent to limit reference points for both the target stock and its predators. Our results demonstrate that an approach based on optimisation is more likely than the current fixed catch limit to achieve CCAMLR’s EBM objectives. The MPC design illuminates the prerequisites for this sort of feedback management approach namely: clearly defined objectives and attitudes to risk; monitoring that includes the highest trophic level for which objectives are defined; and reliable models of system uncertainty. The approach also readily evaluates the trade-offs between objectives given the relevant levels of uncertainty. We conclude that MPC is a promising approach for addressing spatially-resolved multiple-objective problems with high levels of uncertainty, but that its information requirements demand both commitment to monitoring and clarity about objectives.

The Western Antarctica Peninsula and Scotia Sea ecosystems appear to be driven by complex links between climatic variables, primary productivity, krill and avian predators. There are several studies reporting statistical relationships between climate, krill and penguins population size. The Adélie (Pygoscelis adeliae). Chinstrap (P. antarctica) and Gentoo (P. papua) penguins appear to be influenced by the inter-annual variability in the sea-ice extent and krill biomass. In this paper we developed simple conceptual models for decipher the role of climate and krill fluctuations on the population dynamics of these three pygoscelid penguin species inhabiting the Antarctic Peninsula region. Our results suggest that the relevant processes underlying the population dynamics of these penguin species at King George Island (Antarctic Peninsula) are intra-specific competition and the combined effects of krill abundance and sea-ice cover. Our results using population theoretical based models appears to supports the idea that global warming represent a major driver of avian predator populations and its major prey at WAP ecosystem. At our study site, penguins showed species-specific responses to climate change. Chinstrap penguins were only influenced by krill abundance. The contrasting population trends of Adelié and Gentoo penguins appear to be better explained by the “sea-ice hypothesis”. We think that proper population dynamic modelling and theory are essential for deciphering and proposing ecological mechanisms underlying the dynamics of these penguin populations.

We analysed summer diet and fledging mass of macaroni penguins Eudyptes chrysolophus breeding at Bird Island, South Georgia during the crèche period (January and February) between 1989 and 2010. Crustaceans were the main prey accounting for over 90 % of the diet by mass. Antarctic krill (Euphausia superba) was the main prey in 17 out of 22 years. Amphipods (Themisto gaudichaudii) were the main prey in 1994 and 2009, fish in 2004, and euphausiids other than E. superba (Thysanoessa spp. and E. frigida) in 2000. There was no clearly dominant prey group in 1999. The five-year average proportion of E. superba has remained relatively constant at around 68 % since the mid 1990s. Prey diversity and the frequency occurrence of T. gaudichaudii both increased with a decreasing proportion of E. superba in the diet. 59 % of all diets were dominated (> 90 % by mass) by euphausiids, 15 % were dominated by fish or amphipods and 27 % were mixed, suggesting a sigmoidal functional response. The energy and mass of all euphausiids combined (rather than E. superba in particular) in the diet were the most reliable predictors of chick fledging mass; the correlation between model-predicted and observed values was 0.84. The gross energy content of individual meals was often above average in years when the diets contained fewer euphausiids, but fledging mass was always below average in these years. Although macaroni penguins are able to feed on a variety of prey types, chick growth was always severely impacted by a shortage of euphausiids due to higher energy or time costs associated with feeding on alternative prey types.

The breeding performance of seabirds and seals at Bird Island, South Georgia, in the Southern Ocean, has been recorded annually for over two decades as part of a large marine ecosystem monitoring programme. We examined the mechanistic relationships between, and patterns of inter-annual variability in variables for four species to evaluate their potential as ecosystem indicators. These variables included foraging performance, offspring survival, offspring mass, the contribution of Antarctic krill Euphausia superba to the diet, and per capita reproductive performance (PRP: the product of offspring survival and mass). Krill in the diet was correlated across the three bird species (gentoo, Pygoscelis papua; and macaroni, Eudyptes chrysolophus, penguins; and black-browed albatrosses, Thalassarche melanophris) and was a strong predictor of PRP for Antarctic fur seals, Arctocephalus gazella, and gentoo penguins. Offspring survival and hence PRP were largely independent of krill in the diet for macaroni penguins and black-browed albatrosses. The first principal component of all variables summarises the variability associated with krill availability. This was characterised by skewed anomalies with more pronounced but less frequent negatives than positives. Negative anomalies occurred at approximately three year intervals and the most severe occurred in 2009. Above average concurrent sea surface temperature was a necessary but not sufficient condition for extreme (lower 10th percentile) negative anomalies. There were no trends in indicators of krill availability but there were negative trends in some krill-independent variables suggesting changes to other parts of the ecosystem.

We have developed a Geographic Information System (GIS) and accompanying metadata to provide standardised and accessible information on the location and extent of spatial fisheries management measures in the Southern Ocean.  We used the GIS in combination with catch data and the results of the 2007 CCAMLR bioregionalisation exercise to examine the relative spatial distribution of fishing activities, existing management, and ecological characteristics. Such analysis is a necessary part of systematic conservation planning for developing marine spatial protection. Our analysis of catch data focused on the Antarctic krill fishery, which accounted for 92% of catch biomass in the Southern Ocean in 2010/11 (CCAMLR Statistical Bulletin, 2012). 64% of the area managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) was open to directed fishing for at least one species during the 2010/11 season. However, catch limits were unevenly distributed within this open area due to regional differences in the occurrence of target species and level of fishing interest. There were important differences between pelagic bioregions in terms of the fraction of the bioregion that was open to fishing, and the distribution of catch within the open fraction. For example, 94% of the Antarctic shelf slope bioregion was open to directed fishing for toothfish compared to 32% of the Weddell Gyre & Ross Sea Banks bioregion. Only 26% of the total area open to krill fishing has ever been fished, and this fishing is concentrated in 3 of the 7 bioregions found in the open area. Information on the distribution of catches and catch limits among different bioregions could be used to prioritise protection for bioregions that are currently under-represented in marine protected areas (MPAs), or fished to a proportionally greater extent than other bioregions. However, systematic conservation planning should take appropriate account of uncertainties including those relating to scales of correspondence between datasets. Further development of the spatial management GIS could assist CCAMLR in many of its functions relating to fisheries and ecosystems research, monitoring and management (see also WG-EMM-12-XXX, Secretariat paper on development and management of the database).

A Tagging Program for Patagonian toothfish in the longline Argentine fishery outside CCAMLR´s waters was implemented. It was designed to study specific characteristics of the movement and migration of Patagonian toothfish in order to increase biological knowledge on the species and improve resource management in the South-Western Atlantic Ocean. The program started in 2004 and some 4900 juvenile toothfish were tagged and released by Observers form National Institute for Fisheries Research and Development (INIDEP). The chosen tag was an orange standard anchor T-bar tag, similar to those used in other CCAMLR’s toothfish tagging programs. The program was directed to juvenile fish preferably less than 82 cm length TL. Once a tagged specimen was retrieved on board, the tag was removed by the observer who registered its size, weight and recapture position. Otoliths were extracted. Since 2004 up today, 4,913 toothfish were tagged and 70 recaptured. In order to improve the results some recommendations are given.

At its 2011 meeting, the Scientific Committee agreed that a time series of relative recruitments from a well-designed survey could be a useful input into the Ross Sea stock assessment model and endorsed a proposal to carry out this work once the fishery had closed at the end of the 2011/12 season. The first survey was successfully completed in February 2012 and the results presented to the 2012 meeting of WG-SAM (Hanchet al. 2012). In this paper we provide a proposal to continue this time series.

The objectives of this second survey of the time series are as follows:

(i) To carry out the second of a time series of longline surveys to monitor pre-recruit (<110 cm TL) toothfish in the southern Ross Sea (strata A12–C12) using standardised gear in a standardised manner; and

(ii) To define additional experimental stations in adjacent areas to identify areas of high pre-recruit abundance which could be included as additional strata in future annual surveys.

CCAMLR Conservation measures currently require vessels to tag only toothfish with a high probability of survival, but no objective criteria are provided for this evaluation. Achieving this requires an objective evaluation of the probability of survival of each fish to be tagged, which in turn requires objective criteria that link observable characteristics to survival. This paper proposes criteria based on assessments of injuries and vitality used on other species and includes several options for implementation in CCAMLR tagging programmes.

Mark-recapture methodologies are commonly used to inform the management of fisheries. In addition to answering targeted research questions, tagging programmes are typically used to describe movement patterns relative to stock unit identification or to support spatial disaggregation of stock assessment areas, and in some instances to derive population abundance estimates. This paper is intended as a discussion tool to identify and prioritize tagging-related issues for further research drawing on the experience tagging programmes internationally. To the extent that CCAMLR tagging programmes are unique, an evaluation of potential programme biases and corresponding information needs is presented. The paper focusses on the design and implementation of toothfish tagging programmes, but many of the potential issues apply equally to other tagged species such as skates.

With the recognition that CCAMLR tagging programmes are used for abundance estimation of toothfish and skates, tagging operations need to be appropriately supported through documentation, training, and supplies. This paper reviews how tagging programme information could be effectively organised, provides a template training module for observers and vessel crew, and makes recommendations to update tagging protocols and to create a tagging checklist for use at the tagging station.