CCAMLR

We present an initial analysis of the fishing locations, fishing depth and length-frequency distribution of krill at South Georgia during the winter of 2002 and 2003 and compare these with the length-frequency distribution and frequency of occurrence of krill in the diet of Antarctic fur seals. There were significant differences in the mean size of krill taken by vessels/measured by observers that should be addressed prior to more detailed analysis, nevertheless there was considerable overlap in the size composition of krill in the fishery and the diet of Antarctic fur seals. During the period of the winter when there was a reduction in the frequency of occurrence of krill in the diet of seals the fishery appeared to operate at greater depth suggesting a possible depth change of krill during winter. It may be appropriate to review the number of krill measured by observers in order to ensure that other sufficient time can be allocated to other activities, especially the assessment of by-catch.

The current approach to providing advice on the status of the krill-centric ecosystem relies on the evaluation of statistical anomalies in the CEMP database. A new approach based on the ordination of variables according to functional groupings is suggested. This approach uses the methodology developed within WG EMM to produce composite standardised indices (CSIs) from matrices containing missing data to summarise the variability in CEMP parameters.

The methods and presentation of CEMP parameters A1, A5 and A7 where evaluated using simulated time-series data. The effects of sampling timing and intensity during five-day periods for measures of arrival and fledging mass suggested that situations where sampling is distributed unevenly around the peak arrival/fledging date may introduce substantial bias in CEMP parameters A1and A7. The description of foraging trip duration using the mean arising from a bimodal distribution of trip durations may provide a useful index of foraging performance, however, the use of the 90th percentile of the cumulative foraging effort may provide a more sensitive measure of changes arising from changes in foraging strategies of penguins.

The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) is currently considering plausible models of the Southern Ocean ecosystem within the Working Group on Ecosystem Monitoring and Management (WG-EMM). The icefish, Champsocephalus gunnari, is one of the key components in the subantarctic marine ecosystem in the Scotia Sea and northern Kerguelen Plateau areas, as well as supporting commercial fisheries. Data on the species’ distribution, biology, ecological interactions and susceptibility to environmental change are summarised for use in ecological modelling work.

The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) is currently considering plausible models of the Southern Ocean ecosystem within the Working Group on Ecosystem Monitoring and Management (WG-EMM). Epi- and mesopelagic fish are key components in the oceanic (deep water) marine ecosystem throughout the CCAMLR area. While not in most cases the object of commercial fisheries, these generally small (

1. This paper describes temporal changes in foraging range throughout the breeding season of Adélie penguins nesting at Béchervaise Island on the Mawson coast of Eastern Antarctica. A decade’s worth of satellite tracking data was loaded into geographical information systems (GIS) software to produce maps of where the penguins travel to feed during each of the incubation, guard, crèche and pre-moult stages of the breeding cycle.
2. Penguins ranged furthest north during incubation and made their shortest trips during the guard stage of chick rearing. An annually recurrent polyna was consistently used as access to the sea during incubation.
3. Kernel analyses showed that penguins foraged most intensively at the continental shelf break and over submarine canyons, particularly whilst feeding chicks. Birds foraging prior to their annual moult travelled hundreds of kilometres to both the west and east of their breeding sites.
4. Foraging ranges at the different stages of the breeding season are consistent with the changing requirements of adults and chicks. However, increases in range as the chick rearing period progresses are also consistent with prey depletion and intraspecific competition.
5. Projection of the foraging ranges demonstrated for the Mawson coast onto other Adélie penguin colonies in the Prydz Bay region indicates varying degrees of overlap depending on the stage of the breeding season and the distance between populations. Overlap in foraging ranges between neighbouring colonies is least likely when chicks are small due to shorter foraging trips at this time.

The development of a general estimator of abundance would facilitate a standardised approach to regional and circum-Antarctic surveys of land-based predators. Such a generalised estimator is outlined, and its applicability illustrated by adapting it to the specific problem of estimating the abundance of Adélie penguins at regional scales in Antarctica, given a range of logistical scenarios and related survey designs.

There is a large body of existing count data in the literature for penguins at their breeding sites in Antarctica and the sub-Antarctic islands. These data have been summarised into several compilation documents and their accuracy assessed therein on a site-by-site basis. There has been no previous attempt to determine how the accuracy of regional scale abundance estimates derived from these data might be assessed. A formal abundance estimator appropriate to regional scale abundance estimation from existing data is developed and the assumptions underlying that estimator outlined. Existing data for Adelie penguins are then examined to determine how well the estimator assumptions are fulfilled, and hence how accurate regional estimates of breeding populations, as derived from existing data, might be.

It is widely acknowledged that counts of Adélie and other penguin species at breeding sites in Antarctica during the breeding season are influenced by the date at which they are undertaken. A count of some attribute of the population on any date may therefore need to be adjusted by some date-specific factor (termed the availability fraction) if the count is to form the basis of an estimate of the breeding population. Existing time series count data of adult Adelie penguins from a range of sites and years around Antarctica were modelled using quantile regression to estimate the range of the availability fraction at times other than the date of last egg lay. Differences in the availability curve were found between the East Antarctic and Ross sea regions. Spatial and temporal variability in the availability fraction is much higher prior to late November and after early January than through December. Implications for the planning of future regional scale surveys of land-based predators are discussed.

In this paper we present a simple generalised conceptual life history model of Adélie penguins based primarily on data collected from Béchervaise Island, East Antarctica. The model uses life history categories based on an individual penguins reproductive potential in any given year, their past reproductive experience and their spatial location. While there may be generalities which are relevant to other Adélie populations and also other penguin species, details in relation to parameter estimation and functional relationships are likely to differ.