CCAMLR has been using the total catch of krill taken within 100 km of penguin colonies in their breeding season (December to March) as an index of overlap between the potential foraging areas of penguins and the distribution of the krill fishery in Subarea 48.1 (South Shetland Islands). As this index has proven unsuitable for a number of reasons, an alternative method of calculating an index of fishery-predator interaction has been developed. The new index reflects the functional interaction between these two utilisers of the krill resource and is based on a detailed model of penguin foraging patterns combined with catch positions. This analysis shows that the overlap between the fishery and chinstrap penguins is much greater than for other penguins, and that this overlap has been decreasing since 1988.