CCAMLR

Despite much research on Euphausia superba, estimates of their total biomass and production are still very uncertain. Recently, circumpolar krill databases, combined with growth models and revisions in acoustics have made it possible to refine previous estimates. Net-based databases of density and length frequency (KRILLBASE) yield a summer distributional range of ~19 x106 km2 and a mean total abundance of 8x1014 postlarvae with biomass of 379 million tonnes (Mt). These values are based on a standardised net sampling methodology but they integrate over the period 1926-2004, during which krill abundance has fluctuated. To estimate krill biomass at the end of last century we combined the KRILLBASE map of relative krill density around Antarctica with the most recent, acoustics-derived, value for the CCAMLR Synoptic Survey of the Scotia Sea area (37.3 Mt). Thus the CCAMLR 2000 survey area contains 28% of the total stock, with total biomass of ~133 Mt in January-February 2000. Gross postlarval production is estimated conservatively at 342-536 Mt y-1, based on three independent methods. These are high values, within the upper range of recent estimates, but consistent with the concept of high energy throughput for a species of this size. The similarity between the three production estimates reflects a broad agreement between the three growth models used, plus the fact that, for a given population size, production is relatively insensitive to the size distribution of krill at the start of the growth season. These production values lie within the envelope of what can be supported from the Southern Ocean primary production system and what is required to support an estimated predator consumption of 128-470 Mt y-1. Given the current debate over acoustic methodology, plus the need for precautionary management of the developing krill fishery, our net-based data help to set a conservative estimate of total krill biomass.

1. We used the CCAMLR 2000 synoptic survey acoustic dataset to compare pelagic and shelf SSMUs in terms of the frequency of 1nm integration units with krill densities above and below a range of threshold values. 2. In general pelagic SSMUs had markedly lower frequencies of fishable integration units where the threshold density for fishing was set at 100 gm2 following Kasatkina (2003). 3. This was also true with other threshold values in the range 25 to 200 gm2 although the difference was smaller for higher thresholds. 4. The contrasting probability of encountering fishable concentrations in pelagic and shelf SSMUs suggests that the fishery will be less efficient and, perhaps, less economically viable in pelagic SSMUs. This is despite the fact that the absolute abundance of both krill and fishable concentrations of krill is higher in pelagic than in shelf SSMUs. 5. We also derived empirical relationships between SSMU-scale krill density and the frequency of fishable integration units for the full range of threshold levels. These relationships will be useful for linking the scale represented in operating models with those that affect the behaviour and performance of the fishery.

The “CCAMLR-IWC Workshop to review input data for Antarctic marine ecosystem models” will be held at the CCAMLR Headquarters in Hobart Australia on 11-15 August 2008. This paper provides an update on progress towards the holding of this workshop at the CCAMLR Secretariat . A revised budget is presented for consideration primarily to take account of the review materials being produced without expenditure from the budget, the re-costing of hosting the workshop by the CCAMLR Secretariat and the possible cost of publication. This has enabled the funding of more experts to attend the workshop. Coordinators have been appointed for all the data groups with the exception of the flying birds group, the work for which is being discussed with scientists involved in ACAP. An additional expert group has been added early in 2008 to review the state of the datasets on the exploitation of Southern Ocean species, including seals, whales, finfish and krill. A metadatabase has been established. The groups of experts have been assembled and work has been progressing within the individual groups. It is expected that all groups will have papers ready for consideration at the workshop, except for flying birds. The JSG agreed that the synthesis work will occur at the workshop rather than being attempted prior to the workshop. The workshop is open to members of the SC-CAMLR and SC-IWC and their working groups. Many relevant experts have been invited to attend with funding limited to one expert from each group, some experts that cover a number of groups and a group of experts familiar with statistics, assessments and ecosystem modelling. Originally, the outcomes of the Workshop were envisaged to comprise a paper from each of the expert groups, the metadatabase and a short report summarising the workshop and outcomes. When the material is outlined as a complete set the contents reveals itself to be a potentially exciting volume in parts and in total. It is apparent that such a volume could have appeal as book that could be incorporated into library collections by scientists, universities and others interested in the Southern Ocean and the issues faced by the CCAMLR and IWC. The paper describes how such a book might be organised. It also provides commentary on what might be included in the papers and a workshop report. In the case of the latter, it suggests that the workshop report be divided into a number of general categories on the different estimation and modelling tasks. SC-CAMLR (through WG-EMM) and SC-IWC are asked to consider and comment on the progress being made by the expert groups, the issues considered in the paper by the JSG and surrounding publication of the outcomes and whether a book would be a suitable outcome from this work.

The amount of notified catch of krill fisheries is increasing above the trigger level recently, but the reported catch has remained about 100,000 tons. To address this problem, Japan proposes a revision of Conservation Measure 21-03 (2007) Notification of intent to participate in a fishery for Euphausia superb.