CCAMLR

CPUE values of the Soviet krill fishery in 1977-1992 in subareas 48.1, 48.2 and 48.3 are standardized by vessel types, regional fishery associations, months, years and subareas. The causes which determine CPUE variability are revealed.

The paper describes moves towards accounting for the food requirements of some of southern Africa’s seabirds in management of pelagic fish stocks. It also considers moves towards establishing target populations for seabirds in South Africa, especially those of conservation concern. It describes anomalous breeding by several species of seabird at Marion Island in 1997. These are assumed to have resulted from an environmental anomaly that may have been related to the strong ENSO of 1997/98.

The development of the krill fishery can be monitored and predicted using a number of different sources of information. Information on current catches and scientific information on the krill stocks is of limited value in plotting trends in the fishery at its current level. Predictions by Members of their future plans are also of limited use because they ultimately depend on the underlying economics of the fishery. We have analysed predictions made by Members of their future activities and have found that they are generally less accurate than will be necessary to detect trends in the future. Economic information on the krill fishery has been difficult to access in the past but will be necessary to provide reliable predictions of future harvesting trends. Sources of such information are now available but the interpretation of economic and marketing information requires specialised skills which are not generally available in the Scientific Committee. Technological information may provide early warnings of developments that could later herald an expansion in krill fishing. Information on new products from the krill fishery, and new krill processing technology is widely available once patents have been lodged. We have examined patent databases to find information on products and processes involving krill and have found 376 recorded patents. These patents reveal some trends in the development of products using krill. Complete interpretation of technological and market data requires specialist skills which would have to be harnessed if full use is to be made of these sources of information. An expansion in krill fishing to relatively high levels may occur over a short (

The Fourth World Fisheries Congress will be held in Vancouver, Canada 2-6 May 2004, with the theme “Reconciling Fisheries with Conservation” (See www.worldfisheries2004.org). There is an opportunity for CCAMLR scientists to participate in a session focussing on the Antarctic. It is proposed that CCAMLR might wish to nominate co-leaders for this session and that CCAMLR should publicise the existence of this session and venue as an important opportunity to present CCAMLR science in a global context.

1. Estimating food consumption is central to defining the ecological role of marine predators. This study developed an algorithm for synthesizing information about physiology, metabolism, growth, diet, life history and the activity budgets of marine predators to estimate population energy requirements and food consumption.
2. Two species of marine predators (Antarctic fur seal Arctocephalus gazella and macaroni penguin Eudyptes chrsolophus ) that feed on krill in the Southern Ocean were used as examples to test the algorithm. A sensitivity analysis showed that estimates of prey consumed were most sensitive to uncertainty in some demographic variables, particularly the annual survival rate and total offspring production. Uncertainty in the measurement of metabolic rate led to a positive bias in the mean amount of food consumed. Uncertainty in most other variables had little influence on the estimated food consumed.
3. Assuming a diet mainly of krill Euphausia superba , annual food consumption by Antarctic fur seals and macaroni penguins at the island of South Georgia was 3•84 [coefficient of variation (CV) = 0?11] and 8?08 (CV = 0•23) million tonnes, respectively. This was equivalent to a total annual carbon consumption of 0?35 (CV = 0?11) and 0?72 (CV = 0?23) G tonnes year –1 . Carbon expired as CO 2 was 0?26 (CV = 0?06) and 0?65 (CV = 0?19) G tonnes year –1 for fur seals and macaroni penguins, respectively. The per capita food consumption varied depending upon sex and age but, overall, this was 1?7 (CV = 0?22) tonnes year –1 for Antarctic fur seals and 0?45 (CV = 0?22) tonnes year –1 for macaroni penguins.
4. The algorithm showed that the seasonal demand for food peaked in both species in the second half of the breeding season and, for macaroni penguins, there was a second peak immediately after moult. Minimum food demand occurred in both species during the first half of the breeding season.
5. As both Antarctic fur seals and macaroni penguins compete for krill with a commercial fishery, these results provide an insight into the seasons and stages of the life cycle in which competition is likely to be greatest.

The Antarctic fur seal (Arctocephalus gazella) and macaroni penguin (Eudyptes chrysolophus) are sympatric top predators that occur in the Southern Ocean around South Georgia where they are, respectively, the main mammal and bird consumers of Antarctic krill (Euphausia superba). In recent years the population of fur seals has increased whereas that of macaroni penguins has declined. Both species feed on krill of similar size ranges, dive to similar depths and are restricted in their foraging range at least while provisioning their offspring. In this study we test the hypothesis that the increased fur seal population at South Georgia may have resulted in greater competition for the prey of macaroni penguins leading to the decline in their population. We used: (1) satellite-tracking data to investigate the spatial separation of the Bird Island populations of these two species whilst at sea during the breeding seasons of 1999 and 2000 and (2) diet data to assess potential changes in their trophic niches between 1989 and 2000. Foraging ranges of the two species showed considerable overlap in both years but the concentrations of foraging activity were significantly segregated spatially. The size of krill taken by both species was very similar, but over the last 12 years the prevalence of krill in their diets has diverged with nowadays less krill in the diet of macaroni penguins than in that of Antarctic fur seals. Despite a significant degree of segregation in spatial resource use by the study populations, it is likely that the South Georgia populations of Antarctic fur seal and macaroni penguin exploit the same krill population during their breeding season. For explaining the opposing population trends of the two species, the relative contributions of independent differential response to interannual variation in krill availability and of interspecies competition cannot be resolved with available evidence. The likely competitive advantage of Antarctic fur seals will be enhanced as their population continues to increase, particularly in years of krill scarcity.

The present contribution uses data from German surveys in the 1980’ies and the US LTER programme which continuously collected krill demography data since 1993 during the austral summer season in the upstream area of the Elephant Island mesoscale survey. The intention was to compare the recruitment indices derived from these two mesoscale surveys and analyse whether results from mesoscale surveys are representative for a wider region Generally the proportional recruitment indices for one (R1) and two-year old (R2) krill differ substantially between years. However, results were in conformity with the results from other scientific surveys. Recruitment indices showed a significant correlation for age-one-old krill between scientific surveys from the northern Bellingshausen Sea, the Elephant Island area and South Georgia. The correlation becomes weaker for R2 recruitment indices. No correlation was detectable between the krill recruitment of Atlantic and Indian Ocean survey sites. Problems of single-year outliers from Elephant Island are discussed as well as the problem of ‘undersized’ length classes of the age-one-group which occur in the samples of some years.

In marine ecosystems, characterisation of the foraging areas and habitats of predators is a key factor in interpreting their ecological role. We studied the foraging areas of the macaroni penguin Eudyptes chrysolophus at Bird Island, South Georgia, throughout the breeding seasons of 1999 to 2001 using satellite tracking. We investigated differences in foraging ranges and characteristics between different stages of the breeding season, between sexes, between years and between individuals. During incubation, on foraging trips of 10 to 26 d, both sexes travelled long distances from Bird Island (male average = 572 km; female average = 376 km) in a north-westerly direction towards the Maurice Ewing bank; some individuals, particularly males, travelled to forage in the Polar Frontal Zone. In contrast, during the chick-rearing period, both sexes mainly foraged relatively close (average 62 km) to South Georgia over the continental shelf. Foraging trip characteristics differed between males and females during chick rearing: females travelled further on average and on more direct trips. During chick rearing, males and females on longer foraging trips covered greater distances and travelled further from Bird Island. There were no interannual differences in characteristics of foraging trips, although sex differences in some parameters varied between years. The bearings of chick-rearing foraging trips were non-random and most were in a north-westerly direction. Variation, both intra- and inter-individual, in bearings of foraging trips was high. Travel speeds were slower during foraging trips in the chick-rearing period than during incubation, probably relating to the differences in distances travelled. The stage of the breeding season, associated constraints on the penguins at different stages, and sex were important in determining variation in foraging range and characteristics in macaroni penguins, but year and individual effects were relatively unimportant.

Long-term data on the reproductive performance of krill predators at Bird Island, South Georgia where used to produce Combined Standardised Indices (CSI) that reflect processes operating over different time-scales. The output from all three CSIs indicated that in 2002 there were no indications of predators being unable to find sufficient food to provision themselves or their offspring.