CCAMLR

The influences of abiotic and biotic parameters on the occurrence of Antarctic krill (Euphausia superba) concentrations were studied in the waters north of the South Shetland Islands, a major krill fishing ground in the Antarctic, during the 1990/1991 austral summer. From early to mid-summer krill density increased and showed distinct offshore-inshore differences in abundance and maturity stages. In mid-summer, krill density was low in the oceanic zone (8 g m –2, and higher in the slope frontal zone (36 g m –2), being highest along the shelf break (131 gm–2) in the inshore zone. Krill were in the reproductive stage in the oceanic and frontal zones, but non-reproductive in the inshore zone. Water circulation, food and frontal features were considered important environmental factors determining the occurrence of high krill concentrations in these waters. Drifting buoys indicated that the surface water circulation in areas of krill concentrations was characterized by a sluggish current with eddies along the shelf break in the inshore zone and a shear current in the frontal zone, thus enhancing the residence time for krill. Diatom abundance in both the frontal and inshore zones increased from early to mid-summer, improving krill feeding conditions. Gravid females were closely associated with the frontal zone, showing that the latter may also be a favored spawning area because of the higher probability of survival for embryos and larvae, in addition to enhanced opportunities for their transport to nursery grounds by prevailing currents. In the waters north of the South Shetland Islands, krill appeared to be highly adapted for exploitation of the rich food resources of the frontal/inshore zone, taking advantage of oceanographic features that led to their retention in these zones.

Little is known of what happened after the exploitation period with the population of Antarctic fur seal (Arctocephalus gazella) on the Antarctic peninsula region, specifically on the South Shetland archipelago. We compiled historical information for Cape Shirreff and San Telmo islets located on the northen tip of Livingston island, where the most important colony of this species on the South Shetland breeds. From 1991 onwards an ecosystem monitoring program started to develop and detailed population data has been obtained as well as other relevant information. Counts have been developed each season diferentially counting sex and age categories to assess total population. We present the up to date logistic model that describes pup population increase from 1965/66 to 1997/98.
During this last season, a notable population decrease was observed and reasons for this occurrence seem unclear since observed pup mortality was lower than previous seasons, and leopard seal (Hydrurga leptonyx) predation was also lower than last year. We hipothesize that large scale fluctuations in physical oceanographic features (like the current El Niño Southern Oscillation event and related sea-ice extent influence) might be changing krill abundance and distribution, in turn affecting local predator reproductive performance. Hucke-Gaete et al. (1998) report that pup growth rates for 1997/98 season do not reflect an El Niño event, although lower mean weights are reported. Nevertheless, we expect to see during the following split season (1998/99), a further decrease in pup production, lower weights in pups, and considerable decrease in total population due to emigration to better foraging areas.

We investigated the diet and aspects of foraging effort among Adélie Penguins Pygoscelis adeliae breeding at three colonies on Ross Island, in the southwestern Ross Sea -- Capes Royds, Bird and Crozier -- during the chick provisioning period of three austral summers, 1994-95, 1995-96 and 1996-97. During the study period, pack-ice cover differed in waters offshore of these colonies, by colony, seasons and year. Diet differed among colonies only slightly. The fish Pleuragramma antarcticum was the most important prey, especially during years or periods within years when little pack ice was present. With respect to krill, which composed the remainder of diet, juvenile Euphausia crystallorophias were consumed predominantly in a year of heavy pack-ice cover; more adult krill were consumed in two years when pack ice was sparse. Foraging trip duration differed by colony, season and year and was related directly to distance from the colony to the nearest pack ice. The amount of food brought to chicks increased as trip duration increased, to a point (2 d), but then decreased as duration increased further (up to 4 d). On the basis of data on mass of parents and of meal sizes to chicks, it appeared that on longest trips more of the food gathered by parents was used for self maintenance; on longest trips, parents lost body mass. Successful foraging during chick rearing, the period when adult foraging is most intense, appears to depend on the proximity of pack ice to nesting colonies for this penguin species.

The paper presents a program of application of satellite and ship monitoring data on dynamics of the sea surface temperature (SST) in fishing areas For various time intervals (week, month, year, etc.). Sample monitoring of fishing areas in the south-western Atlantic and the southeastern Pacific includes: a set of maps of weekly mean SST and monthly mean SST; resulted maps of gradients, tendencies, difference, and anomalies of SST; analysis of these maps during studying of monthly mean and interannual variability of SST; results of comparison of maps of monthly mean SST in various years and mean long-term SST data for the respective periods. Applications of all kinds of SST maps and results of their analyses in the process of estimation and development of the forecast of fishing conditions are determined.

In March - early April 1997 biological, oceanographic and geological operations were carried out on the Ukrainian scientific research vessel "E. Krenkel" in subarea 48.2. The similar observations, but in much less amount, were carried out in subarea 48.1.
The preliminary results of biological studies make possible to characterize the krill population state, other functionally significant components of the plankton community.

In 1997 it was 30 years from the moment of launching YugNIRO fisheries studies in the Antarctic.
Two essential points should be emphasized in the ideology and methodology of the studies carried out. Firstly, complex monitoring is their basis: in addition to the determination of the commercial potential of fish species and krill, study of the Antarctic ecosystem with its non-biological part was given an important place. Secondly, development of scientific grounds for the rational fisheries was their essential part.

There have been numerous human intrusions in the Antarctic Peninsula and west of the Peninsula. The region is where many Antarctic research stations are situated, and also where the bulk of Antarctic shipboard tourism takes place. A brief summary of this human history in Antarctica reveals a wide range of real and possible disturbances. Potential impacts from human activities continue to exist–and are expected to increase–because of the growing number of expedition tour operators and of the number of trips being offered. In this context, the soon-to-be-effective Antarctic Environmental Protocol is intended to provide a new measure of protection by ensuring that tourism, science, and all other human activities do not have adverse impacts on the Antarctic environment, nor on the value of Antarctica and its associated and dependent ecosystems for the conduct of scientific research. The Protocol requires environmental assessments to be prepared before any such activities take place, and efforts have begun to create a database and inventory of information that assists in both the preparation and the evaluation of these assessments.