CCAMLR

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.

Haul by haul logbook data from the Japanese krill fishery from 1980/81 to 2003/04 fishing season was analysed. By using statistical modeling (linear mixed model) a series of predicted intra- and inter-annual trends of standardized fishery indices are presented. The results strongly suggest that krill fishery in South Orkney and South Georgia area are both operating around a critical point which is just enough to maintain the best factory performance. The status of fishing was not clear in Subarea 48.1 through our analysis. Linear correlation was observed between Catch per Searching Time and Catch per day within their lower range, suggesting these may have some value as abundance index. To refine these indices, it is necessary to collect more detailed information from fishing vessels. It is also important to undertake the same kind of analysis for the fleets from other fishing nations.

The behaviour patterns of Japanese krill fishery vessels in Area 48 were analysed using questionnaires on the reasons why the vessel changed their fishing grounds, which were sent out to of the Japanese fishing vessel since the 1989/90 fishing season. Among many reasons for changing fishing grounds, krill density, krill, size, ice condition, transshipment, and salp-by catch accounted for 95.6% of the changes. Although low krill density was the primary reason for changing fishing grounds, other seasonal factors such as greenness or ice condition could become important. A general picture of the seasonal succession of the Japanese krill fishing operation revealed that they tend to utilize fishing grounds close towards the southern limit within the ice free range. This pattern may well vary between nations, and it is essential to perform similar analyses for the other nation’s vessels. A conceptual model for Japanese krill fishing operation is proposed.

A simple generalised conceptual life history model for Antarctic krill is developed based on observations and data from the literature. The model attempts to take into account the observed relationships between Antarctic krill and its biotic and abiotic environment. Krill life history is thus viewed as an evolved product of interactions between the species and its environment. In particular, the model focuses on the different forces that act on the larval and adult stages.