CCAMLR

The level of observer coverage in the krill fishery and  the  scientific sampling undertaken are summarised.  During 2012 all 12 of the vessels that participated in the krill fishery carried observers for some or all of their fishing operations. From a total of 860 vessel days of fishing in 2012 observations of krill length measurements were collected on 375 ‘days’ and fish bycatch was measured on 554 ‘days’. Krill length-frequency distributions showed that the greatest variability in size structure occurred  in subarea 48.1 during 2012 when fishing occurred both in Bransfield Strait and to the west of the South Shetland Islands.  The 4901 fish measurements from 34 taxa  indicate the vast majority of fish caught as bycatch are <5cm in length.

In 2011/12, 12 vessels from five Members fished for krill in Area 48 and the total catch of krill was 161085 t (Subarea 48.1: 75630 t; Subarea 48.2: 29040 t; Subarea 48.3: 56415 t). The largest catch of krill by small-scale management unit was taken in ‘South Georgia East’ in Subarea 48.3 with a total catch of 50218 t.

So far this season (2012/13), 11 vessels from Chile, China, Korea, Norway and Ukraine have fished for krill in Area 48. The total catch reported to the end of May 2013 was 151161 t, 86% of which was taken from Subarea 48.1. At the time of preparing this report, the cumulative catch in Subarea 48.1 was 146474 t (94% of catch limit 155000 t) and that subarea was closed on 14 June 2013.

Six Members (19 vessels) submitted notifications to fish for krill in Subareas 48.1, 48.2, 48.3 and 48.4 in 2013/14. The total notified, expected level of krill catches is 545000 t. There were no notifications for exploratory fisheries for krill.

A great challenge for Southern Ocean ecosystem science is to assess the status and trends of Southern Ocean marine ecosystems overall, against which change in ecosystem structure and function can be unambiguously assessed in the future.  This challenge includes being able to assess the likelihood of different states in the future.  These requirements are needed by different bodies regionally and globally for making tactical decisions, such as catch limits and conservation requirements in the Commission for the Conservation of Antarctic Marine Living Resources, and to provide strategic advice, such as in the Intergovernmental Panel on Climate Change.  There are three subsidiary questions to this challenge:

1. How should status and trends in those ecosystems be assessed and reported and how will the likelihood of future states be assessed?
2. What are the gaps in knowledge that are required to be able to undertake these assessments?
   a.    what is the current status of Antarctic and Southern Ocean ecosystems overall?
   b.    what are the critical processes, mechanisms and feedbacks that directly influence the population responses of biota to change in their habitats?
3. What observations need to be taken that will indicate a change in state of those ecosystems and provide suitable input to, validation or correction of assessments?

This paper summarises international initiatives and their current activities aimed at delivering circumpolar ecosystem assessments.

In this study, we introduce the initial results from three seasons (2011-2013) of penguin observations made in the waters off the South Orkney Islands. The surveys followed pre-determined transect lines during five consecutive days within late January and early February. Three species of penguins were observed and Chinstrap penguins (Pygoscelis antarctica) dominated in numbers during all three seasons, with Adélie (P. adeliae) and Gentoo penguins (P. papua) only present in modest numbers. The average number of penguins observed per hour increased from year to year, with 7.8 ind/hour in 2011, 32.8 ind/hour in 2012 and 58.5 ind/hour in 2013. Different results also appeared when comparing data collected two times in the same area during the same survey. Future research will consider these results to the differences in study design, density of prey resources and relevant physical factors. This study is part of a larger program that aims to establish and build time series of environmental data, Antarctic krill (Euphausia superba) and krill predator’s abundance and distribution patterns in this area.

The pelagic trawlers involved in the fishery for Antarctic krill (Euphausia superba) apply different trawl designs. Very little information exists on the size selectivity of E. superba. Size selectivity describes a given trawls designs ability to catch different sizes of a population and is valuable information for the management of harvested marine stocks. Size selectivity data is traditionally collected during timely and costly fishing experiments in the field where one design is tested at the time. FISHSELECT is developed as an alternative method, and is based on thorough measurements of the morphology of the species in quest and the shapes of the relevant mesh types, to predict the size selectivity by mathematical modeling. After making modifications with the procedures in FISHSELECT to parameterize morphology, the method proved applicable to determine size selectivity in different trawl designs for E. superba. We present design guides that predict the basic selective properties for E. superba in all relevant sizes of diamond meshes 5 - 40 mm and the opening angles of 10 - 90 degrees. Our predictions are based on the species morphology only, and do not take into account potential behavioral effects. Finally, we discuss how our result can be utilized for management purposes to increase the understanding of the catching process of E. superba and the selective properties in different fishing gear.

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.