CCAMLR

In this work the characteristics of krill transport across the SSMUs determined on the basis of long-term Russian research in Area 48 are considered. Estimates of mean current velocities based on the long-term data from 3012 stations and respective time intervals when the water mass in the study area was totally replaced are presented. It is shown that in SSMUs the multiple total replacement of water masses is possible during one fishing season. These processes of water mass replacement will be accompanied with krill biomass transport across the boundaries of the SSMUs. Our estimates of krill flux out SSMU during fishing season appeared incomparable neither with the historical annual catch within SSMU, nor with the total catch from the Scotia Sea for any fishing season during the latest 20 years. It is shown that total krill biomass of 3.392 mln.t. transported by water mass out three SSMUs is comparable to the total precautionary yield value in the Scotia Sea comprising 3.17 mln.t. It is concluded that krill transport estimates should be taken into consideration in the scheme for allocating the krill catch limit among SSMUs in the Scotia Sea developing by CCMLR. This is primarily referred to the fourth option of the schemes (Hewitt, et al, 2004)

In 2004, the Commission tasked the Secretariat to discuss with the Committee on Environmental Protection (CEP) the nature of available data from the Antarctic Site Inventory, and to invite consideration by appropriate Working Groups of whether the data would be of value to CCAMLR. Information about the data is presented for consideration by WG-EMM.

At Marion Island, there was considerable correlation in numbers of adults breeding at study colonies for both Macaroni Eudyptes chrysolophus and Eastern Rockhopper E. chrysocome filholi Penguins, over 26 and 22 years respectively, suggesting over-wintering conditions may influence the proportions of birds breeding. For both species the time of arrival of females for breeding, and for Rockhopper Penguins the mass of females on arrival, was significantly related to breeding success. Therefore, over-wintering conditions may also affect breeding success. Trends in breeding success at study colonies were more strongly correlated for Macaroni Penguins than Rockhopper Penguins. Macaroni Penguins have a greater foraging range than Rockhopper Penguins when breeding, and may be more influenced at this stage by wider-scale environmental phenomena. For Macaroni Penguins, breeding success was significantly correlated with mass of chicks at fledging. For both species, mass on arrival of males was significantly correlated with that of females. Although both species had low weights on arrival after the El Niño Southern Oscillation event of 1997/98, there was no significant correlation in mass on arrival between the two species. It is likely that at Marion Island their over-wintering grounds are different.

At Marion Island, an outbreak of Avian Cholera Pasteurella multocida killed about 2 000 Macaroni Penguins Eudyptes chrysolophus at the colony at Kildalkey Bay during November 2004. Other colonies of Macaroni Penguins and other species of seabirds were not affected. In March 1993, an unknown disease killed several thousand Macaroni Penguins at Bullard Beach, but also did not affect other colonies or other species of seabird.

The target strength (TS) of Antarctic krill, Euphausia superba, is a scaling factor to convert the acoustic backscattering strength into the population density. Therefore, it is important to improve the accuracy and precision of the TS value. Since in situ and experimental TS measurements of small animals like krill are difficult, the theoretical scattering models are used to predict the characteristics of the TS. For the calculation by the acoustical scattering model, the information of size, morphology, orientation, and material properties of krill are required. There are two important material properties: one is the ratio of the density of the animals to that of the surrounding water (density contrast) and the other is the ratio of the sound speed in animal to that in the surrounding water (sound-speed contrast.). Although these parameters are inevitable for the model calculation, the reports of them are still few. During Antarctic surveys of the Japanese R/V Kaiyo Maru in 2000 and 2004/ 2005, the measurements of sound-speed and density of krill were carried out. We report on those preliminary results. The mean total length and mean density were 43.5mm and 1.0562gcm-3, respectively in 2000 survey, and were 41.7mm and 1.0720gcm-3 in 2005 survey. The corresponding sound-speed contrasts of mean total length 25.1mm and 48.6mm were 1.0442 and 1.0348, respectively.

The work of the Scientific Committee is expanding with a duplication of some functions in different working groups. There is also a need to give time to emerging issues for which there is insufficient time at present in the existing working groups, such as consideration of marine protected areas in a CCAMLR context. It is proposed that the working groups of the Scientific Committee be revised to streamline the work and to help reduce the number of groups needing to be attended by our experts. The Working Groups are proposed to be:
i) Biology, ecology and conservation – to discuss the broad issues and ideas about how the Antarctic marine ecosystem works and general conservation requirements, including the use of marine protected areas in the CCAMLR context,
ii) Development of assessment methods – to develop methods for (a) assessing fish, krill and bycatch populations, (b) status of predator and other populations and habitats, (c) ecosystem monitoring, and (d) estimation of yield as well as (e) methods for evaluating management systems, and
iii) Assessments – to use approved and evaluated methods to assess (a) fish, krill and bycatch populations, (b) status of predator and other populations and habitats, (c) status of the ecosystem, and (d) yield.
The ad hoc Working Group on Incidental Mortality arising from Fishing could be spread across all three with a more dedicated report in the Assessment working group as is the current practice.

The history of human harvests of seals, whales, fish and krill in the Antarctic is summarized briefly, and the central role played by krill emphasized. The background to the hypothesis of a krill surplus in the mid 20th Century is described, and the information on population and trend levels that has become available since the postulate was first advanced is discussed. The objective of the study is to determine whether predator-prey interactions alone can broadly explain observed population trends without the need for recourse to environmental change hypotheses. A model is developed including krill, four baleen whale (blue, fin, humpback and minke) and two seal (Antarctic fur and crabeater) species. The model commences in 1780 (the onset of fur seal harvests) and distinguishes the Atlantic/Indian and Pacific sectors in view of the much larger past harvests in former. A reference case and five sensitivities are fit to available data on predator abundances and trends, and the plausibility of the results and the assumptions on which they are based is discussed, together with suggested further areas for investigation. Amongst the key inferences of the study are that: i) species interaction effects alone can explain observed predator abundance trends, though not without some difficulty; ii) it is necessary to consider other species in addition to baleen whales and krill only to explain observed trends, with crabeater seals seemingly playing an important role and constituting a particular priority for improved abundance and trend information; iii) the Atlantic/Indian region shows major changes in species abundances, in contrast to the Pacific which is much more stable; iv) baleen whales have to be able to achieve relatively high growth rates to explain observed trends; and v) Laws’ (1977) estimate of some 150 million tons for the krill surplus may be appreciably too high as a result of his calculations omitting consideration of density dependent effects in feeding rates.

An ecosystem, productivity, ocean, climate (EPOC) model has been developed in the R statistical language to help explore topical issues on Antarctic marine ecosystems, including impacts of climate change, consequences of over-exploitation, conservation requirements of recovery and interacting species, and the need to evaluate whether harvest strategies are ecologically sustainable. As such, it can be used to facilitate the development of plausible ecosystem models for evaluating management procedures for krill following the recommendations of the workshop held by WG-EMM in 2004. EPOC has been designed as an object-oriented framework currently built around the following modules: (i) Biota, (ii) Environment, (iii) Human activities, (iv) Management, (v) Outputs, and (vi) Presentation, statistics and visualisation. Each element within a module is an object carrying all its own functions and data. EPOC is designed to be a fully flexible plug-and-play modelling framework. This is because of the need to easily explore the consequences of uncertainty in model structures but, more importantly, to enable ecosystem modelling to proceed despite widely varying knowledge on different parts of the ecosystem and avoiding the need to guess model parameters for which no information exists. EPOC provides these opportunities as well as examining the sensitivity of outcomes to changes in model structures, not only in the magnitude of parameters but in the spatial, temporal and functional structure of the system. A case study for Antarctic krill is presented as an example.

Wide-scale monitoring of the status of Antarctic krill resources had been previously conducted by the USSR and its results still allow scientist to prepare forecasts of changes in the ecosystem. However, at present such monitoring seems difficult. Taking into account these points, Ukrainian scientists requested that draft amendments to a number of CCAMLR Conservation Measures be considered to make the System of International Scientific Observation compulsory in Antarctic krill fisheries. Indeed, a widespread introduction of scientific observation on krill fishing vessels can help to ease the existing deficit of fishery-independent krill surveys.

Preliminary analysis of data from the questionnaires of krill fishery behavior in CCAMLR observer manual was undertaken. The analysis revealed possible inconsistency in definitions of the event codes among different skippers. Some suggestions were made to improve the quality of questionnaire format to better understand the nature of the fishery.