CCAMLR

This report summarises the results of krill studies from a large-scale surveys of the Italian Antarctic Oceanographic Cruises conducted in December 1997-January 1998 and January-February 2000. A midwater sampler-trawl (Hamburg Plankton Net) was used to collect zooplankton and fish larvae. Net samples data on Euphasiids were analysed at the aim of: 1) obtain a general picture of interannual and seasonal variability of distribution pattern and abundance of Euphausia superba and Euphausia crystallorophias in the western Ross Sea (Antarctica) in relation to ice cover. 2) Explore the population structure of E. superba and its possible spatial and temporal variations across the investigated area.
The present paper has demonstrated that, in the Ross Sea, during the late spring (1997-98), E. superba and E. crystallorophias had common spatial distribution. Juveniles of E. superba were concentrated in a delimited area in Shelf waters and in general, the maturity stage of this species increased with decreasing of latitude (from 76° to 71°S). On the contrary, during the summer period, the two species inhabited different areas and there weren’t particular spatial distribution patterns in the biological characteristics of E. superba.
For both the periods, the analysis of the biological parameters seems to indicate statistically significant differences in biological characteristics among the hauls (aggregations), while within each haul the parameters are homogeneous.

In the paper these have been discussed the results of acoustic estimation of distribution nectonic organisms, non-krill zooplanctonic fraction and krill as detected my multi-frequency echosounder in 48.4 Subarea.
It has been shown that myctophid fish species are dominated in nectonic fraction backscattering. Nectonic organism distributional pattern is evidently attributed, to a greater degree, to myctophid fish species.
There have been obtained differences between spatial distribution of different groups of pelagic organisms. One can reveal, basing on the results of surveying , the influence of water mass type on distribution of different pelagic organisms groups that form antarctic backscattering layers as follows: krill predominatingly contributes to the antarctic pelagic community within proving ground locations occupied by the Weddell Sea waters and Frontal Zone of Weddell Gyral waters; myctophid fishes prevail in northern proving ground within the Antarctic Curcumpolar Current waters; zooplankton is distributed in the Weddell Sea waters. Though krill and zooplankton major biomasses are concentrated in upper 80-90m layer, high densities of myctophid fish are observed within the whole depth range of 0-350m. At the depth of more than 90m principle backscattering recorders can be pertained to myctophid fish species.
A comparative analysis of mean stratum Sa values obtained for krill and myctophid fishes indicated that biomass of myctophid fish species could be considerable. The estimate of myctophid fish biomass which can be a part of alternative trophic chain in relation to krill is evidently of practical interest .

This paper presents a summary of the recent workshop held in Cambridge, UK, which was convened by Dr JL Watkins to assess the status of papers arising from the CCAMLR-2000 Survey of the Area 48. Key actions and target dates for the publication process are highlighted. An outline of the proposed special volume content is given and synopses of the proposed papers are provided.

This paper describes evidence of antibodies against a virus related with Alphaherpesvirinae sub-family, potentially a phocine herpesvirus (PhHV-1) that affect Antarctic Fur Seals (Arctocephalus gazella) from Cape Shirreff, Livingston Island, Antarctica.
Body fluid samples of 54 A. gazella were collected from 48 live animals and 6 from dead ones during December 1999-February 2000 fieldwork.
Blood, pleural, pericardic and peritoneal fluid samples were tested by microneutralization test using bovine herpesvirus-1 (BHV-1) strain.
Antibodies against BHV-1 were detected in four (7.4%) samples. The utility of the extra vascular fluid for serological research in this matter is suggested. It is also recognized the microneutralization test as sensitive method for this search. This finding also contribute with the knowledge confirming the extended distribution range of herpesvirus, affecting a large number of hosts including A. gazella.
It is strongly trusted the necessary to develop the scientific research on diseases in Antarctic wildlife, considering it interesting to be discussed in the WG-EMM agenda, as an important factor which may affect the population success. This also may provide information to be considered in the Antarctic Treaty System, in order to provide control tasks for regulate the possible disease transmission from or into the Antarctic environment.

Between november and february of the years 1993/94, 1995/96, 1996/97, 1997/98, 1998/99 and 1999/2000, one hundred and fifty three specimens of southern elephant seals, Mirounga leonina, were stomach lavaged at King George Island in order to analyse their diet. The two major prey types were cephalopods and fish which ocurred respectively in 98,1% and 14% of stomachs containing prey remains. The aim of the present paper was to report data on fish prey obtained from seal stomachs throughout the whole study period. One hundred and forty five sagittal otoliths were removed from 16 stomachs containing fish remains. Of these stomachs, 9 belonged to adult females, 6 to juvenile males and 1 to a subadult male. The identification of otoliths revealed the predominance of myctophids as fish prey of seals, representing 76,5% of the fish predated. The most frequent (75%) and abundant prey species was Gymnoscopelus nicholsi which constituted in number 69% of the otoliths found. This species was followed by the nototheniid Pleuragramma antarcticum which represented 11,7% in number and 31,3% in frequency of occurrence. Based on the great distances travelled by seals from their foraging grounds to their hauling sites and the differential rate of passage of fish and cephalopod remains through their gastrointestinal tract, an underrepresentation of the consumption of fish is highly probable. Moreover, according to the movements at sea of southern elephant seals tracked from King George Island we suggest that while myctophids may be their dominant fish prey in areas close to their hauling sites, they are probably replaced by the Antarctic silverfish P. antarcticum as seals migrate southward towards higher latitudes where this species is highly abundant.

The data on Soviet krill fishery in i977-1992 are presented. The fishing effort (FE) developed in 1977-1991 was 50086 fishing days in total. According to the pictures presented FE was distributed between subareas 48.1, 48.2 and 48.3. Monthly FE distribution between subareas revealed the three types of FE distribution in subsequent groups of years: Type I: 1981 and 1982, partly 1979/1980: FE was concentrated in subarea 48.1 in January-April, then moved to 48.3 via 48.2. Type II: 1983, 1984, 1985, and 1986: FE was developed mostly in subarea 48.2, since 1985 the role of 48.3 is increasing. Type III: 1987, 1988 and 1989. FE was developed mostly in 48.3, from March-April to September-November. There are discussed several groups of factors influencing FE distribution, it is very difficult to determine the key one between them. However, it was revealed that the determined types of FE distribution well correspond to spatial and temporal variability of the zonal and meridional atmospheric processes. The prerequisites for the main fishing effort development exist in the subarea where Southern transfers are maximally developed for the moment. The phenomena occur in subareas 48.1 and 48.2 under increase of the zonal western transfers and in subarea 48.3 under their decrease.

The study aimed to test the utility of instruments deployed on marine mammals for measuring physical oceanographic variation and, using this method, to examine temperature variation in the coastal waters around South Georgia. There was a significant correlation between temperature measurements made using a towed undulating oceanographic recorder (UOR) and concurrent measurements from time-depth recorders (TDRs) fitted to lactating Antarctic fur seals foraging from the coast of South Georgia. Congruence was found at horizontal spatial scales from 0.01° X 0.01° to 0.5° X 0.5° (degrees of latitude and longitude), and at a vertical scale of 10 m. However, there was no significant correlation between temperature measured by TDRs in the top 5 m and sea surface temperature (SST) measured by satellite remote sensing. TDR data provided information about temperature variation vertically through the water column, and through time. The UOR data were used to recalibrate the TDR data in order to correct for the slow response time of the TDR thermistor relative to the speed of seal movements through the water column. Seasonal temperature variation was apparent, and temperatures also varied between regions, and with bathymetry. These results were consistent with the current interpretation of the coastal oceanography around South Georgia. In particular, the relationship between on- and off-shelf waters showed larger amounts of warmer surface water in a region in which more run-off was to be expected. The study also showed that Antarctic fur seals concentrate their activity in regions of colder, and presumably oceanic, water. Such instrumented animals could provide near real time data for assimilation into ocean models.

At last year’s meetings WG-EMM and Scientific Committee expressed an interest in summarized information on seabird demography, particularly in relation to generation time and productivity. this represents a substantial task with not inconsiderable resource implications. However, as an initial step, this paper attaches a tabulated review of most of the relevant data up to 1981 (Croxall, 1982). The most important subsequent demographic studies are referenced in the recent report of the SCAR Bird Biology Subcommittee (WGEMM- 00/16). The meeting is invited to consider how it wishes to proceed in respect of such data.

GOOS (Global Ocean Observing System) is a permanent global system for observations, modelling and analysis of marine and ocean variables to support operational ocean services worldwide. It is sponsored by IOC, WMO, UEP and ICSU (see website is http://ioc.unesco.org/goos/).
In December 2000, Dr Angus McEwan, GOOS representative, met with the Data Manager and Science Officer to briefly discuss possible collaboration between GOOS and CCAMLR. It was agreed that any proposals for collaboration received from GOOS would need to be considered by WG-EMM and SC-CAMLR.
This document presents the follow-up letter from Dr McEwan, together with extracts from GOOS’s strategic plan for tracking changes in marine ecosystems.

Variability is a key feature of the pelagic ecosystems of the Southern Ocean and an important aspect of the variation is fluctuation in the abundance of krill, the major prey item of many of the higher predators. Direct impacts of variability in the large-scale physical environment, such as changes in ocean circulation, have been suggested as the main factor generating the observed fluctuations. So far, however, there has been little quantitative assessment of the importance of krill population dynamics in the observed variation. Here, analyses of a model of krill population development and predator diet data from South Georgia were used to examine seasonal changes in the population structure of krill. The krill population model was combined with a size-based selection function and used to generate expected length-frequency distributions in the predator diet through a summer season. Comparison of the model solutions with the predator diet data indicates that the model can reproduce the observed pattern of variation and emphasizes that adult population changes are a key aspect of the interannual fluctuations observed during some years. Low krill abundance was associated with reduced representation of the 3+ age group, whereas when krill were abundant the 3+ age class was the major age group present. The seasonal changes in the population structure in the predator diet involve a complex interaction of relative year class strength, timing of immigration, fluctuations in growth rates and dynamic predator selective effects. Development of the model to examine the interactive effects of changing krill growth and mortality rates will be a valuable next step. The dominance of the changes in krill population age structure underlines the fact that to understand the variability of the South Georgia ecosystem we must identify the major factors generating variability in population dynamics throughout the Scotia Sea.