CCAMLR

INFORMATION FOR THE MANAGEMENT PLAN FOR CEMP SITES WITHIN THE ARGENTINE ISLANDS presented in accordance with Conservation Measure 91-01 (2004) “Procedure for according protection to CEMP sites”, ANNEX 91-01/A “INFORMATION TO BE INCLUDED IN MANAGEMENT PLANS FOR CEMP SITES”. Presented the draft management plan for organization of the CEMP sites within the Argentine Islands.

The dynamic of krill fishery in the Subarea 48.1 and its relation to the environment variability was analyzed.  It was revealed  that the dynamic of ААО indices (Antarctic Oscillation Index) used as an indicator of the inter-annual and long-period fluctuations of hydrometeorological conditions at high latitudes of the Southern Hemisphere was traced through the climatic changes of the environmental parameters (air temperature, atmospheric transport intensity, ice situation) in the Subarea 48. 1. The observed changes in the interannual and seasonal dynamics of the krill fishery in Subarea 48.1 are consistent with climatic changes of these environmental parameters.

Understanding the relative effects of biotic and abiotic drivers of survival, and the interactions between them, is a key component in understanding the factors driving changes in animal populations.  Body size, mass and condition may be important determinants of an organism’s ability to survive periods of low resource availiability or high metabolic demand.  Such effects may be particularly important for naïve juveniles when they first become independent of their parents and must learn to forage for themselves.  Therefore, changes to adult foraging efficiency through intra-specific competition or environmental conditions are likely to impact chick size, mass and condition and may ultimately lead to lower post-fledging survival.  We examine how Adélie penguin chick size, mass and condition varied among breeding colonies of different sizes on Ross Island during a period of high environmental variability.  The presence of two giant icebergs from 2001 to 2005 increased sea ice concentrations, reducing adult foraging efficiency and providing a natural experiment to test the effects of environmental conditions and competition on chick size, mass and condition.  Our results show that the size, mass and condition of Adélie penguin chicks is greater during times when environmental conditions allow for more efficient parental foraging.  In addition, we show that in some cases, increased intraspecific competition may be a more important driver of chick size than abiotic factors, with chicks smaller and lighter at larger colonies. Understanding these patterns will allow better understanding of how such factors as climate change and altered food webs may affect changes in Adélie penguin populations in the Ross Sea and elsewhere.
 

The Adélie penguin (Pygoscelis adeliae) is an indicator species used by the CCAMLR Ecosystem Monitoring Program (CEMP) to detect effects of anthropogenic activities (e.g. commercial fishing) on the Antarctic marine ecosystem.  The goal of this study was to assess annual variation and trends in the number of Adélie penguin breeding pairs at colonies in the western Ross Sea.  High angle oblique aerial photographic surveys of colonies were acquired for the breeding seasons between 1981 and 2012, and counted.  On average 870,465 pairs of Adélie penguins breed in the western Ross Sea each summer, with just over a quarter (27.5%) at colonies on Ross and Beaufort Islands (southern Ross Sea meta-population).  The aggregated colonies of Cape Bird and Cape Crozier had a negative per capita growth rate of -1.8% for the years, 1981-2000 followed by a positive per capita growth rate of 5.5% for the years, 2001-2010.  In contrast, a single declining trend line best represented the number of breeding pairs at Cape Royds for the years, 1981 to 2012.  Colony growth rates for the southern Ross Sea meta-population showed a striking level of synchrony through time.  The partial rate correlation functions for the rates of change versus loge-transformed colony size all showed a significant negative correlation at lag 1 indicative of direct density dependence in the number of pairs returning to the colony each year.  In recent years a number of the Adélie penguin colonies have reached their highest levels since New Zealand began its aerial counts in 1981.  However, the reason for the positive growth rate at Cape Bird and Cape Crozier, but not Cape Royds, remains unknown.  It is likely that the adverse oceanographic and sea ice conditions caused by the grounding of the giant iceberg events (2000-2005) off the southern Ross Sea colonies resulted in adults choosing to abandon or skip breeding in the worst affected years, especially 2001.  The increases in the southern colonies are in contrast to what we observed at Cape Hallett and other northern colonies which exhibited an overall decline or no trend respectively up until our last survey in 2006.  It is unlikely the penguins along the northern Victoria Land coast were affected by the giant icebergs during their breeding since they did not ground for any period adjacent to those colonies suggesting an alternate factor(s) are affecting the birds in that region quite differently.  Two hypotheses: (i) increases in the length of season and spatial extent of sea ice in the north-western Ross Sea region and/or (ii) an increase in a common prey species of the Adélie penguin, Antarctic silverfish (Pleuragramma antarcticum), brought on by changes in the abundance of a silverfish predator, the Antarctic toothfish (Dissostichus mawsoni), by commercial fishing or other reasons, have been postulated as explanations for the increases observed in the southern Ross Sea meta-population, especially over the last decade.

Information on type C killer whales in the Ross Sea region is reviewed, in particular on the trophic overlap between type C killer whales and Antarctic toothfish. Killer whale population ecology (high consumption rates, low abundances, low production rates, often specialised diets, unknown potential for foraging innovation) means that they are particularly vulnerable to changes in the ecosystem. It is also possible that changes in killer whale feeding can affect the structure and stability of whole ecosystems.

There is circumstantial evidence that suggests that toothfish are an important prey item for type C killer whales in the Ross Sea: (1) type C killer whales near McMurdo Sound have been commonly observed carrying toothfish in their mouths; (2) comparison of the relative nutrient density of toothfish with silverfish and other prey shows that toothfish represent a high-energy food resource of much higher quality than other potential prey in the Ross Sea region; (3) densities of other alternative potential prey (Antarctic silverfish, cryopelagic fish) seem too low to justify killer whales coming to the Ross Sea for feeding and the development of a fish-eating ecotype; (4) anecdotal observations of type C killer whales with toothfish in their mouths in McMurdo Sound have declined since 2000, consistent with reduced catch rates of toothfish by scientific fishing in McMurdo Sound, though the reasons for observed changes in this location are not known.

Other information reviewed here is inconclusive: (1) Habitat overlap information is inconclusive, because it is not known to what extent toothfish forage pelagically or how deep type C killer whales can dive. Recent and unpublished information shows that type C killer whales in the Ross Sea can routinely dive to 200-400 m, with a maximum of >700m. This is deep enough to reach demersal prey over much of the Ross Sea shelf. (2) Stable isotope values of killer whales and toothfish do not support or refute the hypothesis that toothfish are a major prey item in the Ross Sea in summer. Information on the isotope values of skin of type C killer whales during the full time period in which  they are in the Ross Sea, and in different locations inside and outside the Ross Sea,  as well as turnover times for stable isotopes in killer whale skin, are required to interpret the isotope data. (3) Comparison between the consumption rates of killer whales and maximum biomass of toothfish potentially eaten by predators at two scales (McMurdo Sound, Ross Sea shelf) suggested that it was possible that type C killer whales could feed substantially on toothfish in summer, but much depends on the number and distribution of killer whales in the Ross Sea region.

At present, the balance of evidence suggests that toothfish are likely to form a significant part of the diet of type C killer whales in McMurdo Sound in summer, but it is not possible to say whether toothfish are an important prey item to type C killer whales in other locations on the Ross Sea shelf (e.g. Terra Nova Bay, Bay of Whales, Sulzberger Bay) or at the scale of the whole Ross Sea shelf and slope.

Basic information necessary to evaluate reliably the risk to type C killer whales in the Ross Sea from the toothfish fishery is urgently needed, including: prey type, foraging behaviour, abundance (and trends) and demographics. Suggested methods are biopsy sampling (analysis for isotopes, fatty acids, genetic tagging), focal-follows (e.g. from boat, ice-edge, helicopter), photographic sightings, tagging (satellite, suction-cup tags), aerial and acoustic surveys.

There is presently debate over the degree to which the fishery for Antarctic toothfish (Dissostichus mawsoni; ‘toothfish’) in the Ross Sea may affect the ecological viability of top predators such as Weddell seals (Leptonychotes weddellii), but available evidence remains inconclusive as a result of both methodological limitations and knowledge gaps.  We present new stable isotope data on Weddell seal prey, consider the assumptions underlying application of stable isotope methodology to Weddell seals, and estimate the potential contribution of toothfish to the diet of Weddell seals using an isotope mixing model.  As a new approach, we also estimate Weddell seal food requirements by considering nutritional quality of potential prey species including toothfish in the context of updated estimates of Weddell seal energy requirements.  The energy density of potential prey items (fish and invertebrates) covers a four-fold range.  Nutritional analysis of Ross Sea prey suggests that toothfish may represent a unique high-energy food resource for Weddell seals that possibly cannot be adequately replaced by other prey, in particular during periods of high energy demand such as late-stage lactation and the post-breeding recovery of body weight and condition.  The assumed dominance of Antarctic silverfish (Pleuragramma antarcticum) in Weddell seal diets should be re-examined given the known biases of methods used to derive diet estimates.  While large (>30 g) silverfish occurring at high densities are a valuable nutritional resource, smaller size classes are unlikely to be adequate to meet the estimated energy requirements of adult Weddell seals.  Our ability to conclusively determine possible dependence of Weddell seal populations on toothfish, and hence possible impacts of toothfish removal by fisheries, is primarily hindered by (a) insufficient information on Weddell seal diet, due to inadequate temporal coverage and biased methodology, and (b) uncertainty regarding Weddell seal abundance and spatial foraging patterns in the Ross Sea region.

We present new censuses data for a suite of chinstrap (Pygoscelis antarctica) and gentoo (P. papua) penguin colonies in the Cierva Cove region of the Danco Coast, including ASPA No. 134. Data indicate an overall increase in breeding population size of chinstrap and gentoo penguins. Given positive population growth in recent years in this rapidly changing environment and a position within Area 48 that is, relatively speaking, lightly fished, we suggest that the Cierva Cove colonies provide an opportunity to explore how monitoring data can provide useful contrasts to other monitoring sites with more fishing activity.

Understanding the temporal variability in vital rates (e.g. growth and survivorship) of wild populations is practically and statistically difficult but crucial for connecting such variation to mechanistic drivers and their population consequences. For somatic growth, empirical estimates of variation are rare because they often require expensive long-term tag-recapture programs. In marine pelagic ecosystems, where many species are difficult to sample and not amenable to tagging studies, researchers have relied on estimating growth from length-frequency distributions. We developed a general approach for estimating growth from observed length-frequency samples by combining kernel density estimates of the length-frequency distribution and the von Bertalanffy growth function. Our approach is conceptually straightforward and easy to implement. We applied the methods to Antarctic krill Euphausia superba collected from the Southern Ocean over a span of 19 yr to document among-year variation in krill growth during the austral summer. Our estimates of growth align closely with existing estimates of growth, but we provide the first estimates of among-year variation in krill growth. We estimate very high among-year variation in growth (annual estimates for a 30 mm krill in the Elephant Island region ranged from 0.00 to0.17 mm d −1 ; mean = 0.073, among-year coefficient of variation  ≈ 0.8). We correlated growth rate variation to estimates of ocean chlorophyll but not to other oceanographic indices, contrasting with results from previous studies. The large amount of variation in growth unexplained by environmental  covariates  has  substantial  implications  for  ecosystem  management  in  the  Southern Ocean ecosystem.

This paper introduces a proposed data integration and assimilation tool to assist the CCAMLR Ecosystem Monitoring Program in obtaining policy-relevant summaries of Adélie penguin abundance and distribution. The engine of this decision-support tool is a physically-based algorithm for retrieval of continent-wide Adélie penguin distribution and abundance from satellite remote sensing imagery. An ecologically-based Dynamic Bayesian Network (DBN) model assimilates remote sensing results streaming in from a multitude of sensors with other sources of information such as field counts and predictions from state-space models of population change. The DBN model synthesizes this data flow into policy ready metrics of Adélie penguin abundance at any user defined spatial or temporal scale. The results will route through a browser based geospatial application custom designed to address the needs and concerns of the Antarctic research and management community. In sum, we propose to develop the data-to-knowledge pipeline required to fully harness the power of remote sensing for effective resource management in the Antarctic. This paper serves as an introduction to our proposed development work (as recently submitted in response to NASA Research Announcement NNH12ZDA001N-ECOF) and a request for input on the design of the associated user interface.
 

The authors analyzed the spatial-temporal structure of standardized indices of catch per effort unit (CPUE)  of Antarctic krill fishery in the Area 48    in  relation to dynamic of ААО indices (Antarctic Oscillation Index) as one of the factors used in analysis of inter-annual and long-period fluctuations of hydrometeorological conditions at high latitudes of the southern hemisphere.  Standardization of CPUE values was calculated on the basis of generalized linear models method with mixed effects (GLMM). Analysis of the time-series of CPUE and AAO indices were carried out using the modern de-nosing data methods, including wavelet transform, Markov’s regression model to determine the fishery regime shifts and multivariable wavelets de-noising. The influence of climate variability was traced in the long-term dynamics of fleet operation including standardized indices of catch per effort unit (CPUE), monthly catches and catches per vessel day.  It was shown that the most important evidence of ongoing climate variability is the fishery regimes switching observed in long-term fishery in the Area 48. It was found that the most significant switching of fishery regime occurred in 2006-2011, when fishery had transferred to the state «high CPUE». This period is characterized by the highest values of CPUE and AAO indices for the whole observation period 1985-2011.  Analysis of krill fishery indices obtained with using different fishing technologies revealed that the “high CPUEs” regime is not associated with the changes in fishery technology and using the continuous fishing method, but is due to the influence of the current climatic changes.