Krill have been called the ‘cornerstone’ of the Antarctic ecosystem. They are the world’s most abundant crustacean. Krill form the staple diet of many animals including seals, whales, fish, squid, penguins and other seabirds.

How much krill is in the Southern Ocean, and how the population fluctuates, are major questions to address in considering the protection of the Antarctic environment.

Krill have been fished commercially for nearly 50 years. The Southern Ocean krill fishery started in the Indian Ocean sector and then spread around the continent. In the 1990s, the fishery began to concentrate in the Southwest Atlantic Sector. The fishing grounds within this sector further concentrated to only a few small locations. This fishery has regained commercial interest due to recent technological developments in harvesting and processing, resulting as an increase to nearly 400,000 tonnes per year over the last decade.

Waters off the Australian Antarctic Territory (AAT) have been regularly fished between 1975 and 1995, with the annual krill catch reaching a maximum of 155,000 tonnes in 1981. Krill fishing in the late 1990s, however, has been between 80,000 and 100,000 tonnes per year. More recently, after a long hiatus, krill fishery started to redevelop off AAT since 2016 although the level of catch is still very small (less than 600 tonnes per year).

Scientists at the Australian Antarctic Division have developed sophisticated echo sounder technology and software to provide the best estimates so far of krill abundance and distribution in the Indian Ocean sector of the Southern Ocean. This information has been used by the international body that regulates the fisheries of the region — the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) — to set conservative, or 'precautionary', fishing limits that allow for the needs of all the other animals in the ecosystem.

Managing the krill fishery needs more than an estimate of how much krill is out there. In ship-based studies and at the Australian Antarctic Division’s unique cold-water krill research aquarium at Kingston, scientists are examining aspects of the biology of krill that will contribute to the sustainable management of the krill resource. Such studies focus on krill growth, ageing and production. These are all important inputs to the mathematical models used to manage the fishery. The combination of survey work, experimental research and theoretical analysis provides a comprehensive and world-leading approach to the study of krill and is an important contribution to the goal of protecting the Antarctic environment.