CCAMLR

With the intent of stimulating discussion, we present four options for subdividing the precautionary catch limit of krill for Area 48 into the small-scale management units (SSMU) adopted at CCAMLR-XXI. The first three are static allocations: the first is proportional to estimated predator demand in each SSMU; the second is proportional to the estimated standing stock of krill in each SSMU; and the third is proportional to the standing stock less predator demand in each SSMU. The fourth option is a dynamic allocation based on land-based predator monitoring conducted just prior to or early in the fishing season.

The various CPUE indices used in Soviet krill fishery statistics and their main sources and primary data for their calculations were considered. The main CPUE indices were catch per fishing day (CFD), catch per extended fishing day (CEFD) and catch per hour (CH). The primary data for all the calculations were catch per haul and haul duration. There is rather high correlation between mean monthly values of CFD and CEFD, and CFD and CH. Instead, correlation between daily values is rather low, due to high fluctuations in hauls duration caused by fishery strategy directed to different final product of fishery: human consumption, krill meal and frozen krill. When considered separately for different strategies and so hauls duration, mean daily CFD and CH are well correlated. Depending on the strategy, number of hauls per day ranged from 1 to 15, mainly 2-4, hauls lasted from 0,1 to 16 hours, mainly 3-8 hours. The higher requirements for the final product quality, the shorter haul duration and so the higher number of hauls per day. The histograms of distribution of various CPUE, hauls duration, number of hauls per day and linear regression equations allowing mutual conversion of the CPUE indices are presented.

1. Changes in species’ abundance and distributions caused by human disturbances can have indirect effects on other species in a community. Although ecosystem approaches to management are becoming increasingly prevalent, they require a fuller understanding of how individual behaviour determines interactions within and between species.
2. Ecological interactions involving krill are of major importance to many species within the Antarctic. Despite extensive knowledge of the ecosystem that they occupy, there is still incomplete understanding of the links between species and the effect of environmental conditions on these interactions. In this study, we extended a behavioural model used previously to understand the interactions between penguins and krill to determine the indirect effect of krill fisheries on penguin foraging success and behaviour in adjacent breeding sites.
3. Increased fishing pressure offshore is predicted to reduce penguin food intake. Given the documented links between krill and penguins, this also leads to a prediction of decreased penguin survival and reproduction. Krill behaviour is predicted to cause stronger effects of krill fisheries than explained solely by the percentage of biomass removed. Environmental conditions that decrease krill growth rates or cause krill to spend time in deeper water are also predicted to increase the magnitude of the effect of fishing on penguin success. We show that changes in penguin foraging behaviour can be used to assess the impact of local fisheries on penguin reproductive success.
4. Synthesis and applications . These results demonstrate that an understanding of predator–prey interactions, indirect effects between species, and individual behaviour is imperative to our ability to manage populations. We describe a general method to use what is known about ecological and evolutionary processes with species-specific information to predict the response of organisms to novel situations. We further show how individual behaviour can be used to assess the impact of human disturbance on ecosystems.

The distribution and abundance of organisms are affected by behaviors, such as habitat selection, foraging, and reproduction. These behaviors are driven by interactions within and between species, environmental conditions, and the biology of the species involved. Although extensive theoretical work has explored predator–prey dynamics, these models have not considered the impact of behavioral plasticity and life-history trade-offs on predicted patterns. We apply a modeling method that allows the consideration of a spatial, dynamic ecological game between predators and prey using a life-history perspective. As an illustrative example, we model the habitat selection of Antarctic krill and penguins during the time when penguins are land-based for reproduction. Although environmental conditions and the life-history constraints of each species have both direct and indirect effects on both species, the penguin’s foraging rule (whether food-maximizing or time-minimizing) has the greatest effect on the qualitative distribution pattern of both species. Size-dependent diel vertical migration of krill also strongly affects penguin foraging patterns. This model generates suggestions for future research and qualitative predictions that can be tested in the field. The application of this method to a specific problem also demonstrates its ability to increase our understanding of important ecological interactions in general.

Infectious diseases have the potential to cause rapid decline and extinction in vertebrate population and are likely to be spreading with increased globalisation and climate warming. In the Southern Ocean and in Antarctica no major outbreaks of infectious diseases have been reported, perhaps because of isolation and cold climate, although recent evidence suggest their presence. The major threat for the Southern Ocean environment is today considered to be fishing activities, and especially controversial long-lining that is assumed to be the cause for the major decline of albatrosses and petrels observed recently. Here we show that two highly pathogenic diseases (worldwide spreading avian cholera, Erysipelas bacteria) are the major cause of the decline on Amsterdam Island of the large yellow-nosed albatross population that was previously attributed to long-line fishing. The diseases are affecting mainly chicks during their first weeks of life with a cyclic pattern between years, but also adult birds that can be found dead on the colonies. The outbreak of the disease occurred probably in the mid 1980s when the population started to crash at the same time that chick mortality increased and adult survival declined. The diseases could today threatening of complete extinction the very rare Amsterdam albatross, and are probably also affecting sooty albatrosses. The spread of diseases in the remotest areas of the world raises major concern for the conservation of the Southern Ocean environment.

We made an attempt to estimate krill commercial biomass density within the fleet operation areas and compare it with critical density values for marine animals feeding on krill. The results of acoustic investigation obtained in the Soviet trawler operation areas in Subareas 48.1-48.4 were used. We also analyzed commercial statistics data, including haul by haul data from Soviet trawlers numbering 22000 hauls for the period of 1986-1990 and those from Ukrainian trawlers for the period of 2001 and 2002 (2380 hauls).
In the course of the recent twenty years, krill has been fished in the areas with biomass density of at least 100 g/m2. This threshold value of krill commercial biomass considerably exceeds a critical value of krill density for aquatic animals feeding on krill and has been estimated at 24 g/m2 (Boyd, 2001). As is evident from comparison of above density values, the fleet and dependent predators will have different density niches.

Presented are the results of krill acoustic survey carried out by Russian RV Atlantida on the South Georgia shelf within the 500-m isobath. The survey was made during the period from February 14 to March 5, 2002. Average krill density in the survey area was estimated at 45.45 g/m2 and total biomass at 1,898,492 ton. The analysis of krill aggregation distribution was made for identification of potential fishing grounds. Also presented are the results of density assessment on potential fishing grounds and a map of their location. Location of potential fishing areas is still another evidence of the fact that no sustainable commercial aggregations are formed during critical period for animals feeding on krill in the area of the South Georgia western extremity where main feeding grounds serving their needs for food exist.

Given the importance and interdependence of diet studies to monitoring work, we compared data on the stomach contents and food load masses among three species of Pygoscelis penguins during chick rearing over the 20-year period from 1981 to 2000. All three penguin species were largely dependent on Antarctic krill (Euphausia superba), which accounted for over 93% of each species’ diet by frequency of occurrence and mass. Gentoo penguins ate significantly more fish than either congener, specifically the benthic Nototheniid species, while Adélie and chinstrap penguins largely ate two species of pelagic fishes, Pleurogramma antarcticum and Electrona antarctica. All species exhibited significant inter-annual variability in mean food load sizes during chick rearing and there was a high degree of coherence among the three species in the years of high versus low food loads. Adélie and chinstrap penguin adults experienced significant declines in body weight during the chick provisioning period in several of the latter years of the study, suggesting food availability may have declined significantly between the earlier 1980s and the more recent 1990s periods. This conclusion is supported by annual US Antarctic Marine Living Resources (AMLR) marine surveys in the area. Finally, we examined the digested portion of the stomach contents and noted a significant increase in the proportion of digested versus fresh stomach contents as the season progressed and as chick food demands increased. We propose that the digested contents of a penguin’s food load has more than twice the caloric value of a comparable mass of fresh krill in the same bird’s stomach. This allows Pygoscelis penguins to significantly increase the caloric value of food brought to their chick per foraging trip. We discuss the energetic consequences of this hypothesis to the energy balance of the birds provisioning chicks and we point out the implications of this finding for past and future studies of penguin energetics using the Doubly-labeled water technique.

A compilation of information and work pertaining to the krill fisheries in CCAMLR waters in presented, including:
• A report on catches for the last, complete season (2001/02) and an update on catches in the current season (2002/03);
• Further development of measures of overlap between the krill fishery and krill predators;
• An updated plan for the krill fishery in Area 48;
• information on the potential of krill products as aquafeeds.

As part of the preliminary analyses undertaken in preparation for the CEMP Review Workshop, the Secretariat has documented serial correlation in time series of CEMP indices. The values input to the serial correlation analysis were the ‘transformed’ annual index values reported in WG-EMM-03/24.
Serial correlation in biological indices occurred in 4, 10 and 33 % of the time series at alpha levels of 0.05, 0.10 and 0.20 respectively. Generally, serial correlation appeared more prevalent in time series from black-browed albatross and Antarctic fur seal, and from the CEMP Indices A1, A3, B1a and C2b.
Serial correlation in environmental and fishery indices occurred in 23, 38 and 55 % of the time series at alpha levels of 0.05, 0.10 and 0.20 respectively. Generally, serial correlation appeared more prevalent in time series from CEMP Indices H3b and F2c.