CCAMLR

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.

Krill demography and recruitment are tracked through time using scientific net sampling and predator diet sampling. Comparisons of these two methods show broadly coherent results but also frequently show differences that have fueled speculation of prey selectivity by predators. Krill, however, are not homogenously distributed and matching temporal-spatial scales of sample collections can be problematic. In this paper we use ARGOS satellite location data from foraging female fur seals to first identify foraging habitat and its proximity to breeding colonies where diet studies are conducted. We compare krill length frequency data collected over the entire West area of the U.S. AMLR survey grid with that collected only in fur seal foraging habitat. Both are compared to krill in fur seal diet. When spatial temporal scales for the two data sets are approximated as close as possible we found no difference in krill length frequency distributions. We suggest that fur seals are not selecting large krill while foraging but are instead selecting foraging locations that have larger krill in densities that maximize energy gain.

Preservation of ecosystem structure is the guiding principle by which the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) endeavors to manage the harvests of living resources of the Southern Ocean (with the notable exception of marine mammals). The experiences of CCAMLR with regard to fisheries on Antarctic krill (Euphausia superba), mackerel icefish (Champhsocephalus gunnari) and Patagonian toothfish (Dissostichus eleginoides) are reviewed. The unifying paradigm employed by CCAMLR is the application of a precautionary approach, which explicitly incorporates uncertainty in the analysis of risk of exceeding defined management criteria. Each fishery, however, presents a unique set of circumstances and unresolved concerns. While the current fishery for krill is small compared to the precautionary limit established by CCAMLR, fishing effort concentrated near colonies of land-breeding krill predators may pose a threat as well as those posed by the broader-scale influence of climatic cycles and trends on krill production. Management of the fishery on mackerel icefish relies on frequent surveys and short-term population projections because of high variability in natural mortality and is further complicated by the dual role of icefish as both consumers of krill and alternative prey to krill predators. While CCAMLR management of the fishery on toothfish is based on longer-term projections and has demonstrated success in addressing incidental mortality of seabirds, large-scale misreporting of catches threatens to compromise the viability of the fishery. These concerns are discussed in the context of CCAMLR’s long-term goal of feedback management schemes, whereby conservation measures are adjusted in response to ecosystem monitoring.

The Japanese R/V Kaiyo Maru will survey to collect data simultaneously on ecological interaction f environment – Antarctic krill – whales in the Ross Sea and adjacent waters during December 2004 and February 2005. Transect lines along 180, 175E and 165E will be set to cover hot spots where suggest high concentrated krill and whales such as the Scot Seamounts Island, the Balleny Islands, the shelf off the Victoria Land and the Bay of Whale Bay. The 175E line, especially, will be surveyed in detail from the surface to near the sea bottom on physical, chemical and biological parameters.

An assessment of the environmental processes influencing variability in the recruitment and density of Antarctic krill (Euphausia superba DANA) is important as variability in krill stocks affects the Antarctic marine ecosystem as a whole. Naganobu et al. (1999) had assessed variability in krill recruitment and density with hypothesized environmental factors; strength of westerly winds (westerlies) determined from sea-level pressure differences across the Drake Passage, between Rio Gallegos, Argentina, and Base Esperanza, at the tip of the Antarctic Peninsula, sea ice cover and chlorophyll-a in the Antarctic Peninsula area during 1982-1998. They found significant correlations between krill recruitment and those factors. Fluctuations in the westerlies across the Drake Passage were referred to as the Drake Passage Oscillation Index (DPOI). In addition, we had extended time series of DPOI using historical data from May 1952 to May 2003 and tested spectra analysis of the DPOI. The spectrum peaks are 20, 35 and 55 months including the short cycles of 6 and 12 months.