CCAMLR

The marine pelagic system around South Georgia is characterised by considerable inter-annual variability which is linked to large-scale climate variability, indicated and probably mediated by local oceanographic and atmospheric conditions. Much of the observed variability in various fitness metrics for birds, seals and fish seems to be connected with the availability of Antarctic krill, Euphausia superba, which is a major prey species for many vertebrate populations at South Georgia. The marine ecosystem at South Georgia is the focus of a major research effort and consequently there are many sources of data available indicating its state. These include remotely-sensed satellite data, fishery data, surveys of krill and mackerel icefish, and monitoring of land-based predators. Each of these data sources revealed a strong anomaly in early 2009. Above average sea temperatures, without any evidence of increased warm water inflow were followed by reduced icefish catches, a paucity of krill in icefish and penguin diets and low krill biomass in the regularly surveyed “Western Core Box”. Consequently many of the nominally “krill dependent” populations of land based predators produced under-weight offspring and the combined standardised index of CCAMLR ecosystem monitoring programme data from Bird Island reached its lowest level in over two decades of monitoring. These observations provide support for the idea that krill is a major mediator of climatic effects on the ecosystem. They also suggest that icefish diets, in addition to metrics from land-based predators, can provide a useful and, potentially, early indication of krill availability.

The region surrounding the South Orkney Islands has been identified by CCAMLR as one of 11 priority areas in which work to establish spatial protection should be focused (CCAMLR-XXVII Report, para 7.2). In 2008, a pilot study undertaken for this region demonstrated that a systematic conservation planning methodology could be effectively used with currently available datasets to provide decision-support for developing marine spatial protection. This paper describes further work undertaken following the pilot study, with the aim of generating products that can be used to inform decision-making on marine spatial protection for the South Orkney Islands region. It concludes that the method outlined in the 2008 pilot study is appropriate for more detailed planning. It goes on to highlight geographic areas that might form the basis of further work, emphasising a number of questions that will help progress the work further. Following further consultation with interested parties and relevant stakeholders, we consider that work will be sufficiently well advanced to submit a preliminary proposal to SC-CAMLR-XXVIII, describing a package of marine spatial protection and management measures that could be considered for implementation in Subarea 48.2. Such measures could include any of the range of tools available under the Antarctic Treaty System. WG-EMM-09/09 describes how these tools can be applied to achieve different conservation objectives. This paper outlines 5 questions to be considered by WG-EMM, to progress the identification of candidate areas for spatial protection and management.

We report annual Antarctic krill consumption estimates for crabeater seals in the Antarctic Peninsula and western Weddell Sea region (90° to 30° W and 60° to 80° S), with special reference to the CCAMLR SSMUs of FAO management Area 48.1. The estimates are based on updated abundance estimates of crabeater seals from the UK-APIS survey conducted in 1999, and were produced with a bioenergetic model specifically developed for crabeater seals.

This work describes a parametric bootstrap model (Davison and Hinkley 1997) for standardising animal count data to a common reference point of breeding chronological for species showing temporal availability to sampling methodology. ICESCAPE (Integrating Count Effort by Seasonally Correcting Animal Population Estimates) is suite of routines that implements a general abundance estimator accounting for availability bias, detection bias, and sampling fractions less than unity (Pollock et al. 2004, Southwell 2004a). Within this resampling framework all measures of uncertainty associated with originally published counts are propagated through to final adjusted estimates. Adjustment for availability bias is achieved by standardising counts to a common reference point of breeding chronology by applying an adjustment factor based on independently measured time-series of availability throughout a breeding season. Such series are typically collected at only a limited number of sites, so a search algorithm is used to determine surrogate availability information for a site when none exists. Importantly, standardisation in this way allows site-specific estimates to be aggregated to achieve region-scale population estimates. By way of illustration, the method is applied to several examples of published studies of Adélie penguin abundance at breeding sites in Antarctica. These examples focus on adjusting counts of adults to an effective number of breeding pairs, although the software has been developed to accommodate adjustment and aggregation of other count objects typical for penguin species (e.g. occupied nest or chick counts). While tailored for Adélie penguins, the method and implementation is sufficiently general to be easily adapted for other colonial land-breeding species showing seasonal variation in availability to sampling methodology.

This document introduces the recent activities and outcome of Japanese scientific observers onboard the commercial krill fishing vessel from 2003/04 to 2007/08 fishing seasons. Main fishing grounds of the Japanese fishery were the Subareas 48.1, 48.2, and 48.3. Recent observation effort was concentrated to the Subarea 48.3. The observer coverage was 32.2 – 51.4 %, and exceeded 50 % in 2007/08 season. The Japanese scientific observers are trained through an educational program on fishery, krill and bycatch species in order to ensure their skill in data and sample collection. Resultant data and samples are analyzed through a cooperative scientific network on Antarctic ecosystem. Biological analysis of the incidentally caught species yielded guidelines for sampling and species identification of larval and juvenile finfish, which was reflected to the CCAMLR observer protocol. Pathological analysis of the krill samples revealed the occurrence of black-spot disease in Antarctic krill and its relation to bacterial infection. Japanese scientific observer activities have thus made considerable contribution to fishery management and marine science. The Japanese government will ensure a certain level of observer coverage to provide information for the management of fishery, krill resources and Antarctic ecosystem.

Krill fishery dynamics was analysed by using Fine-scale haul-by-haul data. Between-haul-distances were well described by a Levy Flight type random walk model. The inferred distribution pattern of fishable target concentrations showed differences between Subareas with targets in Subarea 48.1 being most sparsely distributed compared to Subareas 48.2 and 48.3. Commercially viable CPUE was estimated to be 12 tonnes/hour and 7 tonnes/hour in autumn in Area 48.1. Fishers seemed to be forced to make a number of long distant movements at the beginning of the fishing season, and autumn was suggested as optimal season since generally less searching seemed to be required due to higher target density in the fishing grounds.

Sea ice plays a critical role in structuring ecosystem dynamics throughout the Scotia Sea (SS) region, and variations in ice extent are hypothesized to affect predator populations in this area directly. A paradigm guiding recent research in the Western Antarctic Peninsula (WAP) region of the SS, the “sea-ice hypothesis”, suggests that declines in the seasonal extent and duration of sea ice, owing to climate change, have led to declines in “ice-loving” Adélie penguin (Pygoscelis adeliae) populations, while “ice-avoiding” chinstrap penguin (P. antarctica) populations have increased (1-5). However, 30 years of field studies in the WAP, coupled with more regional surveys throughout the Scotia Sea, refute this hypothesis; both Adélie and chinstrap penguin populations in this region are declining dramatically. Here, we present evidence supporting an alternative, more robust, hypothesis that explains both increases and decreases in penguin abundance as a result of changes in abundance of Antarctic krill (Euphausia superba) in the SS region. Linking trends in penguin abundance with trends in krill biomass can explain why populations of both Adélie and chinstrap penguins increased after seals and baleen whales were over-harvested (6) and, more recently, are decreasing in response to climate change. Thus, while the “sea-ice hypothesis” predicts that chinstrap penguins will benefit from climate change, the “krill-biomass hypothesis” leads to the contrasting prediction that chinstrap penguins are highly vulnerable to the current regime of climate warming.

This brief review documents the species composition of prey consumed by the Antarctic toothfish, Dissostichus mawsoni, in the Ross Sea. The diet for a sample from McMurdo Sound in the southwestern Ross Sea indicates that fishes, especially Pleuragramma antarcticum, and mysids dominate the diet by both frequency of occurrence and dry weight. P. antarcticum is 71% by occurrence and 89% by weight; the corresponding figures for mysids are 60% and 11%. Channichthyids (icefishes) are the second most abundant prey fish. Farther north on the shelf edge and slope, fishes and cephalopods (squid) are the most frequently consumed prey groups at 78-86% and 5-14%, respectively. Pleuragramma are absent from the warmer slope waters and thus prey fishes were other notothenioids and non-notothenioids. Channichthyids and the macrourid (grenadier or rattail) Macrourus whitsoni dominated the diet at 54% and 37%, respectively. In the deep oceanic waters (60-70°S) north of the shelf break the diversity of pelagic and epipelagic fishes is low. Here the diet of D. mawsoni consists of relatively small squid of at least six different genera. It can be concluded that D. mawsoni is a generalized piscivorous predator that feeds primarily in the water column and occasionally on the substrate. There is variability in the diet within Subarea 88.1 that reflects the abundance of various species of prey fish within the shelf, slope and oceanic communities of the Ross Sea.

On the basis of circumstantial evidence, an elevated likelihood exists that Antarctic toothfish and the most-caught by-catch species, macrourids, in the Area 88 fishery are important components in the diet of the Arnoux’s beaked whale (Berardius arnouxii), which is a component of the Ross Sea top predator guild.