CCAMLR

The requirements of an ecosystem approach to management of Southern Ocean resources are outlined. This highlights the need for information on harvested and dependent species their interaction and the manner in which their populations vary naturally. Large scale interactions are catered for the Krill Yield Model. Smaller scale interactions centre around three main categories, the availability of krill and variation in vital rates of the dependent species and the overlap between commercial fishing and predator foraging. The CCAMLR Ecosystem Monitoring Programme (CEMP) provides a good framework within which to investigate krill availability. Vital rates can be investigated directly and also with respect to CEMP. Overlap between fishing and predator foraging is being monitored. A mechanism for bringing these various components together as an ecosystem approach to management is discussed.

The Balleny Islands area contains special values which New Zealand believes are worthy of protection. New Zealand's past proposals have not yet achieved consensus support and the process for designating marine protection within the Antarctic Treaty System is not clearly established. New Zealand hopes that through a fully consultative process with CCAMLR partners, a new proposal which represents the best method of protecting the important values of the Balleny Islands would be developed for future presentation to CCAMLR. New Zealand also supports continued work on the processes for designating marine areas under both the CCAMLR and the ATCM's Environmental Protocol regimes.

Data from the krill questionnaire are presented for the Polish-flagged vessel Acamar fishing in Subarea 48.1 in March-June 2001; five questionnaires were completed. Submission of these data were delayed due to email communication problems with the vessel. This is the first set of questionnaires to be completed and returned to the Secretariat.

Vessels from Japan, Republic of Korea, Peru and the USA had participated in the conduct of five acoustic/oceanographic surveys from late December 1999 and to early March 2000 in conjunction with CCAMLR 2000 survey. Time-series acoustic data from the coordinated survey were analyzed. Excluding the highest and lowest surveys, biomass densities on three remaining surveys were 49.2 g m-2 (CV 19.5 %), 39.5 g m-2 (CV 15.2 %) and 43.0 g m-2 (CV 14.1 %) over a nine-week period. Maps of biomass density for each of the surveys are presented, and examination of these maps suggests three consistent area of high krill density; near the east end of Elephant Island, mid-way between Elephant and King George Islands, and near Cape Shirreff on the north side of Livingston Island. It appears that highest densities of krill move closer to the shelf break as the season progresses. This apparent movement is complemented by a change in the demographic structure of the population. The smaller size modes disappear and krill are more sexually mature later in the summer. If the lowest estimate is treated as the result of measurement errors, then the consistency between the four other surveys suggests low variability in krill biomass north of South Shetland Islands throughout the summer of 1999/2000. Future work analyses could include analyses of patch sizes and densities along transects as a means of investigating variations in krill availability to predators under conditions of constant krill biomass density. Additional oceanographic observation together with satellite-derived information could be jointly analyzed to explain variations in krill abundance and dispersion patterns.

We develop a new approach to quantifying habitat use within the foraging ranges of satellite-tracked seabirds. We applied kernel estimation techniques to 167 days (3738 locations) of data from black-browed and grey-headed albatrosses Diomedea melanophris and D. chrysostoma during the chick-rearing period of the breeding cycle at South Georgia. At this time the activity range of these two species covers an estimated 440 000 and 640 000 km², respectively, with very substantial overlap. In contrast, kernel estimation reveals that the main foraging areas of these two sympatric, congeneric species are very distinct. Based on location density categories accounting for 50% of locations, the foraging areas cover c. 81 500 and c. 119 700 km², respectively, with 42% and 50% of the range of one species overlapping with that of the other.

In terms of the convention governing the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), management advice for the Antarctic krill (Euphausia superba) fishery should take the needs of the predators of krill into account in order to reduce the risk of deleterious impacts on such predators (e.g., baleen whales and numerous fish, seal, penguin and flying bird species). A single species yield model is currently being used by the CCAMLR Scientific Committee to recommend an annual krill catch limit, which is expressed as a proportion (??= 0.116) of a survey biomass estimate. This approach takes the needs of predators into account in only a crude way by assuming that a median krill escapement of 75% of its unexploited biomass would be sufficient to meet the needs of predators. A krill-predator modeling procedure is presented that could be used to directly assess the impact of krill harvesting on krill predator populations and therefore to revise this recommended harvesting level (?) for Antarctic krill. Application of a deterministic form of this model to an Antarctic fur seal (Arctocephalus gazella) data set from Bird Island, South Georgia, Antarctica, indicates that the level of krill fishing intensity (?) that would reduce this population to half the equilibrium size in the absence of krill fishing (?half) lies between 0.03 and 0.18, which includes the level recommended by CCAMLR. This large range results primarily from the sensitivity of the model to the maximum growth rate parameter, for which a range of 5-15% yr is investigated. A plausible range of values for this parameter (5-15% yr) results is estimated ?half values from 0.04 to 0.23. Stochastic calculations (which take account of interannual fluctuations in the abundance of the krill population due to recruitment variability) yield higher estimated ?half values than the less realistic deterministic calculations. However, simulation tests indicate that the estimated ?half values are biased upward; this modeling approach is therefore likely to yield ?half values that would lead to a depletion of the Antarctic fur seal population to more than half its pristine size.

Euphausia superba Dana (Antarctic Krill) has been recognized as a key forage species in the Antarctic ecosystem. This species serves as prey for many organisms in the ecosystem and has also been the target of an small industrial fishery since the mid 1970s. New quotas have recently been set but there is concern that the reduction in krill biomass due tome fishery may have impacts on other krill predators such as penguins, seals and whales.
In order to evaluate the effects of krill fishing on the trophic web, it is necessary to have better knowledge of the ecosystem structure and dynamics. This can be achieved by studying community interactions, such as those between predators and preys, as well as competitors for a common resource. In this context we aim to investigate whether the krill fishery and the top predators are competing for krill biomass. This is a cooperative pilot project led by University of Concepcion, Chile with the Fisheries Centre at University of British Columbia, Canada.
In a pilot study Ecopath with Ecosim 4.0 is being used to develop two mass-balance models of the Antarctic ecosystem, one for CCAMLR area 48.1 and another for areas 48.2 and 48.3 combined. Organisms in the system were combined into groups (of one or more species) on the basis of their feeding behavior, growth rate and their present or potential fishing importance, in order to simulate the trophic interactions of the system. Both models are being constructed with the same structure to allow comparisons between the two. Although this modeling tool has some limitations and several assumptions, the construction of these models is a step towards investigating and identifying major gaps in knowledge and potential impacts of krill fishing upon the ecosystem.

The paper submits the design of the acoustic survey that should be carried out in the next Italian expedition to the Ross Sea (2002), for eventual changes, improvements and suggestions.