CCAMLR

Our long-term seabird research at Admiralty Bay has documented annual variability in the life history parameters of the breeding biology and ecology of Adélie, gentoo, and chinstrap penguins. Long-term data acquired on these species including: survival and recruitment, population size and breeding success, diets and foraging ecology, provide clear evidence linking offshore biological and physical processes to their effects on dependent predators in the Southern Ocean. Our most recent results present a conceptual model linking increasing temperatures and decreasing sea ice cover in the Antarctic Peninsula region to declines in krill and penguin populations. Winter temperatures in the Antarctic Peninsula region have increased 4-5°C over the last 50 years (Smith et al. 1996, 1999), affecting the periodicity of sea ice cover in the region. This climate change, and the associated reduction in winter sea ice cover, has profoundly impacted the Antarctic, krill-based food web (Loeb et al. 1997, Smith et al. 1999, Trivelpiece and Trivelpiece, in prep.).

This information paper is a compilation of websites and publications on Marine Protected Areas (MPAs). The paper is intended as an educational guide and contains an array of national, international, academic, governmental, and non-governmental sources. The list is not exhaustive and should be considered as a starting point for further research.

This paper presents vertical distribution of temperature, salinity, density and flow across the Drake Passage. The seventh Antarctic Ocean Survey cruise by the R/V Kaiyo Maru of the Japanese Fisheries Agency was conducted in the waters around the Antarctic Peninsula in 199/95 austral summer season. In the survey, oceanographic observations were carried out along the north-south line from 56-21 S, 66-37W to 61-49S, 58-28W across the Drake Passage from 1 to 9 December 1994. The Polar Front recognized by a steep gradient in temperature was located between 58-00S and 59-00S. The Antarctic Surface Water, defined as water temperature 0°C or less, was distributed from 58-40S to the southernmost station, 61-49S. The flow across the line was eastward through the whole except the weak flow through some sections. The maximum speed of the flow was approximately 30cm/s corresponding to the Polar Front zone. Upwel1ing of the Warm Deep Water was suggested in the costal water north of the South Shetland Islands.

CCAMLR Conservation Measure 32/X sets a 1.5 million metric ton precautionary catch limit on krill (Euphausia superba) in Statistical Area 48. The measure also implies the application in future of precautionary limits could be applied to subareas or local areas. Nine alternative methods of determining subarea or local area krill catch limits are evaluated relative to six criteria: (i) the degree to which information on biological relationships is considered, (ii) the cost of data collection, (iii) the reliability of required information, (iv) the ease of enforcement, (v) the effects on current fishing patterns, and (vi) the potential for delay in implementing the alternative. An alternative is less likely to adversely impact dependent species (e.g. penguins and seals) if the ecological relationships between krill and their predators are explicitly considered and the potential for delayed implementation is low. Therefore, we consider the following tradeoff to be important: choosing a biologically explicit alternative and delaying implementation, or choosing a biologically unrealistic alternative and implementing a management scheme immediately. We recognize that other tradeoffs may be equally important. Alternatives that allocate the 1.5 million ton limit by evenly dividing the catch among subareas or by using historical catches to set limits can be categorized as having a low potential for delaying implementation, but they ignore information on biological relationships. Alternatives based on protective zones, critical periods, predator censuses, and predator-prey models include large amounts of biological information, but may not be practical in the near future. Alternatives based on continental shelf area, simple pulse fishing, and krill surveys are not biologically explicit and result in delayed implementation. None of the alternatives are categorized as being both biologically explicit and immediately available for implementation. However, two of the alternatives (i.e. protective zones and critical periods) are unsatisfactory only because they would alter current fishing patterns. These two alternatives could be implemented immediately if the CCAMLR Member nations to are willing to tolerate changes in current fishing patterns.

One of the important problems in interpreting CCAMLR-2000 results is how they reflect the krill biomass status, is it high, medium or low at the present time. The comparative analysis of krill biomasses derived from trawl catches was carried out; retrospective data of three Soviet surveys, covering the main part of the CCAMLR-2000 area, were used: RV “Argus” (27.01.84-16.03.84) and RV “Evrika” (11.10.84-14.12.84 and 20.01.88-09.03.88). There were used similar gear (Isaak's Kidd Midwater Trawl) and methods of sampling, but sampling was carried out in the 0-100 m water layer instead 0-200 m in CCAMLR-2000. Krill biomass index calculated for the whole area of Soviet surveys doesn't reveal any significant changes, being in the limit of 15.3-20.3 g/m2. When assuming that changes of average weight density reflect biomass variability, it may be suggested that value of the total krill biomass in the area 48 is quite stable during last seventeen years. It is to be noted however that due to difference in layers sampled during CCAMLR-2000 and Soviet surveys, krill biomass derived from data collected in 80-s may be considered as overestimated comparing CCAMLR-2000 results, the rate of overestimation is unclear. If it is true and level of overestimation is considerably high, we have to admit increase in krill biomass since 80-s, however rate of this increase is impossible to determine on the present stage.

The oceanography of the South Georgia region is principally that of the Southern Ocean rather than the South Atlantic. A combination of factors, including advection, local bathymetry and high local productivity, leads to relatively large concentrations of krill (Euphausia superba) in the region and this is a food source for large populations of penguins and seals that breed at South Georgia. A history of over-exploitation of the marine resources of the region has led to the development of ecosystem approaches to management. The current system for managing krill harvests includes precautionary features that account for interannual variability in krill populations and the food requirements of natural predators. However, in future it may be possible to use information from the natural krill predators to set reasonable levels of krill exploitation.

The study tested the hypothesis that the distribution of critical habitat for foraging by female Antarctic fur seals breeding at the island of South Georgia was influenced by physical gradients in the oceans and also by the need to avoid local competition for food. It also tested the hypothesis that fur seal predation was capable of causing local depletion of prey species. When foraging in support of dependent offspring, fur seals travelled down physical gradients defined by the bathymetric features of the continental shelf around the island of South Georgia. Fur seals foraging from different sites followed the same pattern of travel. There was no detectable difference in this behavior among years when there were different amounts of prey available. Females were constrained to forage mainly within 100 km of the location at which the offspring was being raised. When this constraint was removed at the end of lactation, females foraged to much greater ranges and there was evidence that they dispersed to specific regions associated with the continental shelf east of Patagonia (>1000 km) and to the northern edge of the Antarctic pack ice (500 km). A model of the spatial distribution of foraging by lactating female fur seals predicted spatial distributions that were consistent with past observations from ship-based surveys. The model also allowed estimation of the spatial impact of fur seals on krill. This suggested that, in extreme cases and assuming that krill influx is limited, female fur seals could eat most of the krill present in some regions where they forage intensively. However, mean consumption was about one-tenth of the mean density of krill.

1. This study examined the changing status of the marine ecosystem at the island of South Georgia (Southern Ocean) using up to 27 variables measured over 22 years from 3 upper trophic level predators that specialise in foraging upon krill (Eupuasia superba Dana). These variables included population size, breeding performance, offspring growth rate, foraging behaviour and diet. A method was developed for reducing these multivariate time-series to a single vector, called a combined standardised index (CSI).
2. Sensitivity analyses showed that missing values had a large effect upon the accuracy of the CSI but this effect was reduced if the individual variables were highly correlated. The level of correlation and proportion of missing values within the empirical data set were within the acceptable range. Individual variables had widely varying influence upon the CSI but, in general, those with longer time series had the greatest influence.
3. Principal components analysis showed that variables representing offspring growth tended to explain the greatest proportion of the variability in the CSI and this was followed by variables representing diet.
4. There were 3 years in which the CSI showed extreme and significantly low values. There was a significant non-linear functional response (similar to the Holling Type II functional response) between the overall CSI and krill biomass and a similar relationship existed when the CSI was calculated for each species individually.
6. Separate analysis of variables that were likely to be representative of changing population size showed the presence of a significant decline between 1977 and 1998. There was no trend in the CSI from variables representative of foraging conditions during the summer breeding season. The study has shown that the marine ecosystem at South Georgia shows acute but transient variability that is amplified in the response of upper-trophic level predators. There is less certainty that trends in populations are a consequence of shifts in the degree to which the ecosystem can support krill-feeding seals and penguins.

This paper describes current research plans to estimate the size of land-based marine predator populations breeding at South Georgia with a view to providing critical data about interactions with commercial fisheries. The research will also develop methodologies that reliably assess trends in the abundance of these populations. The research will focus upon predator species that depend upon marine resources that are also harvested by commercial fisheries, principally Antarctic krill. It will concentrate upon those species where there is a high probability of interaction with fisheries and significant potential for resource competition under existing fisheries management policies. The research will also develop new methods that reliably estimate predator population sizes whilst minimising the level of disturbance associated with data collection.