Antarctic krill Euphausia superba. (Photo: Somas.stonybrook.edu)

Antarctic krill biomass high in nearshore waters

Researchers from Stony Brook University and the Southwest Fisheries Science Centre (SWFSC) conducted the first multi-year survey of the Antarctic krill (Euphausia superba) population in coastal waters near Livingston Island in Antarctica. They discovered significantly higher krill biomass density in nearshore waters than in offshore waters.

They used smaller vessels that allow access to shallow, nearshore waters, and also found that these had less interannual variation than offshore waters. The findings were published in the July issue of the Canadian Journal of Fisheries and Aquatic Sciences.

Antarctic krill – the minute shrimp-like animals that make up an essential part of the Southern Ocean food chain -- comprise an important food source for penguins, seals and certain whales in the Southern Ocean. Krill are also fished to be used in aquaculture feed and human dietary supplements.

Using a small boat, researchers were able to measure the amount of krill in shallow, close to shore areas near fur seal and penguin colonies on Livingston Island. (Photo: Joseph Warren, Stony Brook University)

"Nearshore krill biomass is generally most accessible and attractive to land-breeding predators as well as to human fishers competing for this valuable resource," said Dr Joseph Warren, assistant professor in the School of Marine and Atmospheric Sciences (SoMAS) at Stony Brook University.

Previous population surveys of Antarctic krill were limited to offshore sampling because large research vessels cannot safely make their way in shallow nearshore waters. But with the funding offered by the National Science Foundation Office of Polar Programmes and the US Antarctic Marine Living Resources programme, Warren and Dr David Demer, leader of the Advanced Survey Technologies Programme at the SWFSC, ran six acoustic surveys from small boats in the shallow waters north of Livingston Island.

Warren and Demer studied the abundance and distribution of Antarctic krill in coastal waters across several mi of shore from 2000 through 2007. They deployed their equipment from a 6 m inflatable boat and thus were able to conduct their measurements in waters ranging from 500 to just 2 m in depth.

The scientists compared their observations made in the waters both nearshore and offshore the western Scotia Sea carried out during the same year.

"Although the spatial area of our nearshore survey is quite small when compared with that of the entire Scotia Sea, the high and stable densities of krill in shallow water may be more important ecologically than the offshore krill," said Warren.

The School of Marine and Atmospheric Sciences is the State University of New York's centre for marine and atmospheric research, education and public service. It has more than 85 faculty and staff and over 500 students and is at the forefront of advancing knowledge and discovering and resolving environmental challenges impacting the oceans and atmosphere.

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