Krill

Antarctic krill, Weddell Sea, Antarctica

Krill species bio

Common Name

Antarctic krill

Scientific Name

Euphausia superba

Stats

Length: up to 6cm

Weight: up to 1g

Status

Listed as Least Concern (IUCN Red List)

How much krill is in the Southern Ocean?

Scientists estimate that there are over 700 trillion Antarctic krill adult individuals in the Southern Ocean – reaching an estimated collective biomass between 300 to 500 million tonnes – greater than the weight of all humans on Earth!

What do krill eat?

Antarctic krill eat microscopic phytoplankton, single-celled marine plants that drift up near the ocean’s surface. In their larval or juvenile stages of life, krill feed on the green algae that grows on the underside of sea-ice.

Which animals eat krill?

Krill are a critical food source for many of the larger species at the top of the marine food chain. In one day, a single blue whale can consume 3.6 million krill, a single crabeater seal can consume 11,000 krill and an Adélie penguin can consume 1,200 krill. That’s a lot of krill in one day!

What are krill swarms?

Krill are often found in large groups or swarms, ranging from several hundred individuals to millions of individuals. Antarctic krill can form super-swarms that span tens of kilometres wide and can even be seen from space!

What is the average lifespan of Antarctic krill?

It is estimated that a single krill can live between 5 to 10 years. Adult krill can live in diverse environments throughout the Southern Ocean – from the water’s surface to the seafloor.

However, their early life cycle phases as larval and juvenile krill rely deeply on sea-ice habitats, living underneath the ice to feed on algae and hide from predators. Warming temperatures in the region are resulting in the decline of these critical sea-ice habitats and are threatening krill populations.

What is krill often used for?

Harvested krill is mainly used for the production of krill meal and krill oil, which in turn is used for animal feed and direct human consumption through health products.

On average, it takes about 6.5 tonnes of krill to produce 1 tonne of krill meal, although this ratio depends on the size of the krill and the time of year.

Antarctic krill are central to the Southern Ocean food web

Antarctic krill are the primary food source for countless species within the Southern Ocean, such as whales, seals, fish, penguins and other seabirds. Without them, the entire marine ecosystem could collapse.

Krill (Thysanoessa spinifera) underwater © naturepl.com / Visuals Unlimited / WWF

Antarctic krill are carbon-storing powerhouses

Antarctic krill store carbon in their bodies and transport it to the deep ocean through the release of faeces and moulting of their exoskeleton. Reports revealed that krill in the Antarctic Peninsula and Scotia Sea can sink an estimated 23 megatonnes of carbon annually, which is then stored in the deep ocean for at least 100 years.

Antarctic krill also play an essential role in regulating and storing atmospheric carbon – helping to maintain stable levels of carbon dioxide in our atmosphere.

Climate change

Climate change is bringing unprecedented change throughout the Antarctic region. As water temperatures continue to rise, the sea-ice habitats that protect krill nurseries will melt, further shortening the suitable season for krill growth and reproduction. As the primary food source for many species, this could have widespread ecological impacts for the entire Southern Ocean ecosystem.

Krill industrial fishing

A large-scale industrial krill fishery operates around the Antarctic Peninsula. The market for krill oil as a pharmaceutical food supplement, like Omega-3 dietary supplements, is predicted to grow by 10% per annum from 2021 to 2031 – an increase that would require current catches to almost double.

Krill fishers tend to return to areas where they have successfully fished before, creating a concentrated fishery that overlaps with important feeding grounds for krill predators, like humpback whales and Adélie penguins. This method of fishing causes localised depletion of krill.

Researchers prepare to fly a drone over a humpback whale © Duke University Marine Robotics and Remote Sensing Lab. Research conducted under permit by NOAA.

Working to further our understanding of Antarctic krill

WWF works alongside researchers from national Antarctic programs and leading universities to further our understanding the role of Antarctic krill in the global carbon cycle and identify solutions to minimise the threats krill face.

We are also researching the impacts of climate change and fishing on krill populations – and how it can further impact krill predator species like whales, penguins and seals.

This research will go on to inform robust conservation policy that better protects wildlife and wild places in Antarctica.

Protecting important Antarctic krill habitat

WWF is working alongside various stakeholders and governments across the globe to advocate for establishing a network of Marine Protected Areas around Antarctica – providing greater protections for krill and the many species that depend on them.

We also advocate for precautionary ecosystem-based fishery management. This approach looks at the broader interactions within a marine ecosystem to identify management strategies that can help sustain healthy marine ecosystems, the fisheries they support and the broader ecosystems they impact.