CCAMLR

The report presents a methodology that can be used to estimate the total finfish bycatch of the Area 48 krill fishery and quantify the impact of bycatch on the finfish stocks using data that is currently available, applied to data collected by Scientific Observers on the FV Saga Sea.

Estimates of bycatch rates per tonne of catch were made at a family level for Channichthyidae, Nototheniidae and Myctophidae species using delta-lognormal GLMs presented in Martin et al. (2012).  The bycatch rates were applied to estimates of krill catch to estimate precautionary total bycatch numbers of each family for both low sea-ice and normal sea-ice years.  Biological parameters for Champsocephalus gunnari and Notothenia rossii were used to convert total bycatch numbers to biomass at age of 50% maturity removed from stocks due to finfish bycatch at a family level, for Channichthyidae and Nototheniidae species respectively.  Family specific biomass estimates at age of 50% maturity were then compared to available abundance estimates of Channichthyidae and Nototheniidae species at a family level, and at a species level for C. gunnari and N. rossii.

This methodology takes account of explanatory variables that are significantly associated with presence/absence of finfish bycatch in estimates of finfish bycatch rates in the Saga Sea krill fishery.  The methodology can also provide quantitative analysis of the impact of the krill fishery on finfish species at a family level, as well as for individual species.

This paper describes the main results obtained in krill fishing (Euphausia superba) made by the conventional trawler Betanzos in the Antarctic region (Subareas 48.1, 48.2 and 48.3), between June 2011 and April 2012. This report highlights haul-by haul distribution, catches, trawl depth, fishing yields and length frequency distributions of captured krills.

Features of behavior, birthing process, pups nursing of Weddell seals were studied.

Studies of the growth (at birth to 21 days age) of young seals were conducted. Seven seals born in the “Akademik Vernadsky” station were used in the experiment (two males and five females). They were weighed every three days. The live weight was determined by using the obtained data in different periods of growth and its absolute, average and relative growths.

CCAMLR’s working group on Ecosystem Monitoring and Management intends to evaluate candidate feedback management approaches for the Antarctic krill fishery in the southern Drake Passage and Scotia Sea. The Foosa ecosystem dynamics model was developed to perform spatially resolved, stochastic simulations of krill, its predators and fishery. It has been used to provide advice on the spatial allocation of the precautionary catch limit for krill. Foosa might therefore be a suitable simulation platform for evaluating feedback management approaches. Although Foosa resembles a minimum realistic model, it has 50 categories of input parameter and the four parameterisations used to provide spatial allocation advice each required values for 2,311 distinct inputs. In the absence of guidance about management reference points, the modellers provided advice in terms of 41 illustrative reference points intended to represent the key objectives of ecosystem based management: ecosystem productivity, health, resilience and services. Foosa was developed and evaluated through iterative interaction with scientific working groups. There is a global need to develop strategic frameworks for assessing uncertainty in ecosystem dynamics models. Such a framework could incorporate elements of the evaluation of Foosa, but it should also include analysis of the sensitivity of model outputs to model inputs. Here we provide a local sensitivity analysis for Foosa. Some of the outputs used to provide advice on the spatial allocation of krill catch were insensitive to all perturbations, whereas the response of others was upto 8 times the perturbation. They were most sensitive to a parameters controlling predator recruitment through stock recruit relationships and pre-recruit mortality.  A parameter mediating the effect of a forcing function on krill recruitment, which was used to condition the model on historical dynamics, was also important. It is apparent from our analysis that sensitivity is as much a function of model outputs as inputs, which suggests that indentifying quantitative reference points for ecosystem based management will be an essential part of any strategic framework for assessing uncertainty.

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.