Krill found in waters around the Antarctic Peninsula and Scotia Sea, which sits between Antarctica and South America, are worth an estimated $US15.2 billion ($A24b) each year in carbon storage, according to a World Wide Fund for Nature report.

The carbon capture comes from the prawn-like crustaceans, which are typically 6cm long and weigh about one gram, dropping their faecal pellets and outer skeletons to the bottom of the ocean.

This process was worth the equivalent of sinking 23 megatonnes of carbon annually into the deep ocean, where it could be stored for 100 years, the report said.

In comparison, the annual value of Antarctic krill fishing was $US250 million ($A400m), about 60 times less than the carbon value.

The value of the krill as a carbon sink was calculated based on the estimated "social cost of carbon", or the price in US dollars of emitting an extra tonne of carbon dioxide after factoring in the net damages from its impact on global climate change.

WWF Antarctic conservation manager Emily Grilly said the report showed krill were worth more to nature and humans in the ocean than if they were removed.

"Krill are individually small but collectively mighty. That certainly applies to their ability to store carbon and help maintain stable climatic conditions that are beneficial for humanity," she said.

The conservation organisation says the report highlights the need to prioritise better protection for Antarctic krill, rather than expanded industrial harvesting of the crustaceans.

But the organisation that oversees Antarctic krill harvesting, the Hobart-based Commission for the Conservation of Antarctic Marine Living Resources, says the annual catch of the crustaceans represents a tiny fraction of the total population.

Commission executive secretary David Agnew told AAP previous surveys showed there were about 60 million tonnes of krill in the region, while the annual harvest limit was 620,000 tonnes - about one per cent of the total.

"Preserving the key role of krill in the ecosystem, maintaining the ecological relationships between harvested, dependent and related species, and preventing changes to the Antarctic marine ecosystem, are fundamental objectives of the (commission)," he said.

Antarctic krill are the main diet of whales, penguins and seals, and are considered one of the richest concentrations of animal biomass in the sea.

A British Antarctic Survey study published in 2020 found krill transferred 0.3 million tonnes of carbon daily into the ocean, the equivalent of the UK's entire domestic emissions each day.

When harvested commercially, krill are used to make aquaculture, livestock and pet feeds, as well as for supplements for humans.

Australian Associated Press