Antarctic krill

Antarctic krill
Antarctic krill (Photo: Stephen Brookes)
Euphausia superba reared in the aquarium viewed through a microscope.Krill swarmAntarctic krillEarly stage of krill larvae after hatchingThe krill aquarium facility at the Australian Antarctic Division headquarters in Kingston, Tasmania.

‘Krill’ is a general term used to describe about 85 species of free-swimming, open-ocean crustaceans known as euphausiids. Antarctic krill is one of the 85 species of krill that lives in the Southern Ocean.

Scientific name

Euphausia superba

Physical description

With their large black eyes, krill are mostly transparent, although their shells have a bright red tinge from small pigment spots. Their digestive system is usually visible and this is often a vivid green from the pigment of microscopic plants they have eaten. Adult Antarctic krill are approximately six centimetres in length and weigh over a gram.

Distribution and abundance

Antarctic krill are one of the most abundant and successful animal species on Earth. Scientists estimate there are about 500 million tonnes of Antarctic krill in the Southern Ocean. The biomass of this one species may be the largest of any multi-cellular animal species on the planet.

As krill come to resemble adults they begin to aggregate into huge schools or swarms, sometimes stretching for kilometres in every direction, with many thousands of krill packed into each cubic metre of water, turning the water red or orange.

Most of the time the schools stay deep in the water during daylight hours and only rise to the surface at night. It is not known why swarms are occasionally seen at the surface during broad daylight.

Fishery

Commercial krill fishing began in the early 1970s and the prospect of a free-for-all fishery for Antarctic krill led to the signing of a unique fishing treaty in 1981. The Convention on the Conservation of Antarctic Marine Living Resources is designed to protect the Antarctic ecosystem from the consequences of rapidly-expanding fisheries, and to aid recovery of the great whales and some of the overexploited species of fish.

The fishery is managed through an international body (CCAMLR) which sets limits on the krill catch taking into account the needs of other elements of the ecosystem.

Scientists at the Australian Antarctic Division study krill to provide a better understanding of krill life cycles so that the fishery can be better managed.

Breeding

Female Antarctic krill lay up to 10,000 eggs at a time, sometimes several times a season.

Diet and feeding

Antarctic krill are mainly herbivorous, feeding mostly on the phytoplankton (microscopic suspended plants) of the Southern Ocean and, to a lesser extent, planktonic animals (zooplankton).

In winter, they have to use other food sources such as the algae which grows on the underside of the pack ice, detritus on the sea-floor or the other animals in the water. Krill can survive for long periods (up to 200 days) without food and can shrink in length as they starve.

Most of the larger Antarctic animals, the seals, whales, seabirds, fish and squid, depend directly or indirectly on Antarctic krill.

The Convention on the Conservation of Antarctic Marine Living Resources is designed to protect the Antarctic ecosystem from the consequences of rapidly expanding fisheries, and to maintain ecological relationships of the Southern Ocean ecosystems including aiding in the recovery of some of the over-exploited species of fish. The fishery is managed through an international body (CCAMLR) which sets limits on the krill catch taking into account the needs of other elements of the ecosystem.

Scientists at the Australian Antarctic Division study krill to provide a better understanding of krill life cycles so that the fishery can be better managed, and to understand the impact of environmental changes such as ocean acidification on the ecosystem.

Take a tour of the Antarctic krill aquarium

[Video]

Take a tour of the Antarctic krill aquarium

Video transcript

Nick
Good morning everybody, and welcome to a very wintry day in Hobart, the Antarctic Gateway city down to Antarctica. We're at the Australian Antarctic Division Headquarters here in Kingston, and we're here to celebrate Science Week. I'm Nick Gales, and with me is my friend and colleague, Rob King, who's our krill expert. I'm the Director here at AAD, and as part of Facebook Live today in Science Week, we're going to take a walk through the Division and end up down in our Krill Aquarium. On the way, we're going to talk about why krill is really important, we're going to talk about the work we do on it, and we're going to meet some of the scientists and other people who work here, and let you know all about krill. So, Rob, how long have you been working on krill for here at the AAD?

Rob
I've been working on Antarctic krill now for 25 years, and that's on one species of krill. But you know, there are 85 species of krill around the planet, but this one species, Euphausia superba, is the linchpin in the Southern Ocean eco-system. All of the big stuff that people know about, the whales and the seals and the penguins, rely on that krill being there in vast swarms. That's why there's at least 25 years more work to do on Antarctic krill.

Nick

There's always more work. So, before we go down and see the krill, we're going to do a couple of things, and the first thing is to have a look at a map of Antarctica, and just orient you about where we do the work, and where these types of krill live. So, this is a strange map for a lot of people – we've got Antarctica down here at the very south of the globe, sitting in the middle of the map, and right up in the north, in the top corner here, you can see Hobart and Tasmania, and the red lines coming down here are the ways we travel on our ships to get down to our three Antarctic research bases, at Casey and Davis, and furthest west out at Mawson. And Rob, where is it we do most of the krill research?

Rob

So, while we're coming into those bases, we're also travelling over the prime krill territory really, which is all of this around east Antarctica, south of 60 degrees, is teaming with krill. And last year we sailed across one school of krill that was 200,000 tonnes in one school, about a nautical mile wide. That's why whales swim all the way from Australia to Antarctica each year, to each krill, there's so much there.

Nick

So, the work you've done so far has been on the Aurora Australis, but of the course the exciting news, as much as we love Aurora, is that she's getting a little old now, and we're about to start building a new Icebreaker. In fact, construction has started on this wonderful new ship already, and Rob, I know you've had a lot to do with the design of the ship to enable it to really be the foremost ship for krill research. What kind of things have made this ship special for krill work?

Rob
It's really exciting to be building a ship like this, and the bits that I'm most interested in are welded together now. Because it's this wet well and moon pool in the base of the ship. When we go to Antarctica, the sea is frozen over with solid ice. You can't get to the water to sample it, to get krill out of. This ship has doors that open in the bottom of the hull, so you can lower equipment, remote controlled vehicles, nets, and all sorts of things, into the water and take samples. Plus, we have a wet well where five tonnes of water every minute will flow through pipes into there, to filter out krill and plankton. So, this is a feature that no other vessel has ever had, so we're really excited to work there.

Nick
And for those just joining us, I'm Nick Gales, I'm the Director of the Antarctic Division, and with me is Rob King, and we're taking a tour – a Facebook Live tour – of our facilities, with a big feature on our Krill Aquarium and krill. We've just been looking at our new Icebreaker, and one of the exciting things we're doing with the Icebreaker is we've been looking for a new name. We've had a big competition, where school kids all around Australia have contributed, and we'll be getting close to announcing a new name, and the schools who have contributed the winning name will be able to send some kids with us, this coming summer, down to Antarctica. So, we're really looking forward to announcing the new name of the ship and seeing it steam up the Derwent River in Hobart, in just a few years'time.

So, if any of you have any questions as we go through, please send them through. We'll do our best to answer them as we go, and I know Rob will go online after we're finished going live here, and answer some more of your questions. One of the really interesting things around krill is that a lot of animals depend on eating them for their own lives. And here at the Antarctic Division, we have scientists working on krill and also on the very largest of animals who eat them. So, Dr Elanor Bell is one of those people.

Elanor

Hi Nick, Hi Rob.

Nick

Do you want to tell us a little about the work you do, and especially how it is you get an insight into how whales live in the Southern Ocean and interact with the krill?

Elanor

Absolutely, Nick. Well, as you've just said, whales are the largest creatures on the planet, and one of the biggest species we work with is the Antarctic Blue Whale, which can grow up to 30 metres long, and they can eat up to three tonnes of krill in one day. So, Rob, your krill are in big trouble.

Rob

That's what they're there for.

Elanor

What one of the exciting things we do is, we can use technology, such as satellite tagging, to track whales and work out where they're going to find their food, how deep they dive, how often they dive, what type of krill they're targeting. So, I was very lucky recently, to work in the West Antarctic Peninsula, which is a part of Antarctica, below South America. And we were putting out satellite tags on the Minke whales, and again, looking at information about how they were using the krill, where they moved to get it. But the most exciting tag we put out was a video suction cup tag. Now, in the Antarctic, around the peninsula, the humpback whales in particular, eat so much krill that they're fat and they're lazy, and they're completely gorged, and they just sleep around the surface in the day, so we can creep up to them in small boats, slap video suction cup tags on their backs, and those video suction cup tags give us a whale's eye view of what the whales are feeding on. So, we can watch them with their huge mouth engulfing swarms of krill, swallowing the krill down, and then we also get information about then how they're interacting with other whales and the environments. It's very, very exciting stuff.

Nick

Now, that's fantastic, because they spend most of their time under water, so it's pretty amazing to get those insights.

Elanor

We don't normally see that and you can find it all on our website, there's lots of footage and lots more information about the research we do.

Nick

Fantastic. Thanks so much Elanor.

Elanor

Bye, Nick.

Nick

For those of you have just joined us now, I'm Nick Gales, and this is Rob King, and we're at the Australian Antarctic Division Headquarters in Kingston, in Hobart Tasmania, and we're taking you on a tour around the facilities, finishing off in not too much time with the Krill Aquarium down the road. So, if you have any questions, please send them through and we'll be doing our very best to answer them. On our way to the Krill Aquarium, we're going to be talking a bit around how krill fit into the whole marine system. And we're next going to talk to somebody who's a real expert on that, and find out what role krill really play in the great Southern Ocean. So, Rob, you've had a lot to do with this sort of work over the years yourself.

Rob

Yeah, I mean the work we're doing in the lab that we're going to see shortly, is all about getting data to put into things called models, and models are really how we predict the future.

Nick

Well, the specialist in this field is Jess Melbourne-Thomas. Welcome Jess.

Jess

Hi Nick, Hi Rob.

Nick

Do you want to start off, telling us a little bit about a word we use all the time – we talk about eco-systems all the time, and I'm not sure everyone really understands what an eco-system is, so can you just tell us a bit about that, and what role krill play in the eco-system in the Southern Ocean?

Jess

Yeah, definitely. So, Nick, the eco-system is literally everything. It's all of the component species, it's the way that they interact with each other, including who eats who, and it's also the way that they interact with their environment. And so, krill are particularly important in the eco-system, partly because so many things eat them, including whales, but also seals and penguins, and a whole range of other species. But also, because they play other roles – for instance when they form huge swarms, they can actually physically mix the water, because there's so many of them. They play a role in recycling nutrients that are then important to the phytoplankton that they eat. So, there's lots of ways that krill play a really central role in the Southern Ocean eco-system.

Nick

All right. And so, my understanding is then that you use models to try and work out all those interactions, and how they live in that environment. And again, it's one of those words people don't often understand exactly what a model is, so how do you go about developing models for krill in the Southern Ocean?

Jess

Yeah, that's a good question. So, a model is literally a simplification of reality. So, it's something that we can use to test our ideas about the way that the real system works. So, for instance, if you close your eyes and try to cross the living room, you've got a model in your head about where the furniture is so that you don't bump into it. And the kind of models that we use in our work are mathematical models that again, are simplifications of this really complicated real eco-system. And in fact, they're the only tools that we have available to try to peer into the future and ask questions about the way that eco-system might respond to changes in the environment, or to changes in the way that humans interact with it.

Nick

Okay. So, they're really important. So, you sit at your desk, you do all this clever work with these eco-system models, have you ever actually been down south on the ship and had a look at the krill, so you can see them in the wild?

Jess

Yeah, I have, and I think that's a really important part of – <video dropped out> 09:12.6 – 09:34.0.

Nick

We're dropping out a bit now, so for those of you who have just joined us, you're at the Australian Antarctic Division in Hobart in Tasmania. We're doing a tour of the – <video dropped out> 09:41.7 – 09:43.8.

Okay – for those of you, thanks for your patience, we're just having a couple of drop out problems, and we're at the Australian Antarctic Division here in Kingston in Hobart, having a tour of our facilities, and we're about to head down to the Krill Aquarium. We've got krill expert Jess Melbourne-Thomas and Rob King with us, and we'll be meeting another person before we get down to the krill. So, Jess, thanks so much for talking to us about your work.

Jess

An absolute pleasure. Have fun. Bye.

Nick

See you later. We've got fairly extensive buildings all through here, and the area we're going through now is where a whole lot of our very clever technical people work to develop all the kind of equipment and sensors that make our work in Antarctica possible, and that's a key part of the work we do here, isn't it Rob? You'd really heavily on it.

Rob

Yeah. I mean, these guys run when they see me coming because they're just so useful these people. This is an electronics engineers, instrument technicians, marine science gear offices, and together they build the gear that we can ask questions that have never been asked before. And then we bring the data back and analyse it. And it is such an exciting way to do research, because you're doing stuff that just hasn't been done, and you couldn't do until this gear was built. So, we really do rely on them.

Nick

Now, that's great. And remember everyone to please –

But we'll be getting to answer some of your questions in just a moment. We might just pause here in the corridor for a moment, because we've got some beautiful photographs, taken with a scanning electron microscope of tiny little animals. Do you want to tell us a bit about them, Rob?

Rob

Yes. So, some of these are the phytoplankton that form the base of the Antarctic food chain. So, this is what krill are eating. Maybe 250 different species of these floating around the Southern Ocean, photosynthesising and putting all that energy from sunlight into joining water and carbon dioxide together, to make complex organic molecules, and that is the start of the whole system. And what people probably don't realise is that they think of the big stuff in the Southern Ocean, they think of blue whales, and they think of seals and penguins and things, but really the biggest biomass in the ocean is this single-celled phytoplankton.

Nick

So, these are like the forests of the Southern Ocean.

Rob

They're the forests of the Southern Ocean.

Nick

And they feed the krill.

Rob

And they feed the krill, which means, this way shortly, when we go into the aquarium, you're going to see big bad cultures of these, because we're trying to feed krill exactly the same thing they'd be eating in the Southern Ocean.

Nick

So, earlier on, we were talking to Jess and we were talking to Elanor about the animals that eat krill, but we're also aware that people go down into the Southern Ocean and go fishing for krill, and it's quite an important fishery, and a growingly important one. So, we're here to talk to Gill Slocum, who's the Commissioner for CCAMLR. So, Gill, did you want to start off telling us what CCAMLR is, and why it's important for krill fishery and the management of it.

Gill

Sure Nick. So CCAMLR is the Commission for Conservation of Antarctic Marine Living Resources. I know it's a bit of a mouthful. And it's an international organisation that's made up of 25 member countries, and those 25 member countries get together here in Hobart every year, in October, and while they're here they're responsible for making really important decisions about how we can protect and conserve the Southern Ocean marine eco-system. And some of the most important decisions that we do make every year are around how we manage the fisheries, including the krill fishery, and make sure that the amount of krill that the fishing vessels take out of the marine environment, make sure that we allow for the needs of the penguins and the seals, and the whales, and all the other animals that rely on krill for their survival as well.

Nick

So, it's a really important function.

Gill

Absolutely.

Nick

And are there many countries roll up for these discussions?

Gill

Yeah. So, as I said, there are 25 member countries, and we have all of those countries turn up every year, and a whole bunch of other stakeholders as well, both the fishing industry and environmental organisations who are really passionate about the Antarctic environment.

Nick

Great, thanks Gill. We've got a question I see coming in from Sacred Heart in Geelong, and they want to know how do krill survive in water at such very low temperatures? Rob, you're the expert.

Rob

That's a great question. We don't survive in water like that. If we jumped in the water at that minus one degree temperature, we would find ourselves freezing to death within five minutes or so. Krill are ectotherms – that means they don't generate a bunch of heat and try and stay warm in that water, they're the same temperature as the water they're swimming in, and they've evolved over millions of years to work in those conditions. All their enzymes work best at that temperature. If you try and keep krill in an aquarium above about three or four degrees, they start to go downhill quite quickly. So, everything about them is adapted to that because they've made gradual adjustments through time and evolution. And one of the big interesting things for us is, with the rate the planet's changing at the moment, on scales not seen in the geological record, can krill keep up with that evolutionary process? We just don't know the answer yet.

Nick

Well, I think we might talk about that when we go and see the krill. So, thanks again, Gill.

Gill

No worries, thank you.

Nick

Cheers.

Gill

Bye.

Nick

Now, for those of you just joining us, you're at the Australia Antarctic Division's Headquarters in Tasmania, and we're doing a tour of our facilities, and we are about to go and see the krill, which is the highlight of the show. So, we got an aquarium set up here at the Antarctic Division Rob, and I know you've been involved with this pretty much from the start. Do you want to tell us a little about what we're about to see?

Rob

Yeah, so this aquarium replaces one that was really a rudimentary aquarium, that was just built into a cold room in the 1980s. That was when we were using the Nella Dan as our research vessel, so even before the Aurora. So those very first experiments we ran were in fridges, but this aquarium was purpose-built for krill and runs at 15 degrees for us, but –

So, we're going into the aquarium now Nick, and we'll go through the quarantine footpath, because we are running a little piece of Antarctica here, in Tasmania, so it's a quarantine boundary there that we're crossing through.

Nick

And this is only one of two aquariums in the whole world that's managed to run krill all the way through their whole life cycle.

Rob

Yeah, that's right. There's the Port of Nagoya Aquarium in Japan, and we send them krill periodically so they can conduct research with it and make some displays as well.

Nick

So, another question that's just come in as to why aren't krill kept just in Antarctica? Why do we actually keep them all the way up here in Hobart, so far from their normal area where they live?

Rob

Well, that's a very good question. You can do the best research in the field. Every scientist wants to work on their animal in the actual field where the animal lives. Unfortunately for humans, that's on top of a rolling ocean, which can be absolutely ferocious, where you can't do any research at all. So, what we do is bring the krill back here and have the best of both worlds. By bringing them here, we can have scientists fly in from anywhere in the world, land here, do research on krill, take their data and publish it. We can have a turnaround of a few weeks, from collecting data to sending off to a paper for peer review. If you try and do that in Antarctica, you're looking at a two to three year process.

Nick

Fantastic. And what are these amazing tubes, these great big – they look like a sports drink collection. What are these Rob?

Rob

Well this is a sports drink for krill. This is Antarctic phytoplankton - you're looking at two different species here. This one has chlorophyll A for the photosynthetic pigment that it's using to trap the energy from those lights, to make that first step in the food chain. Whereas this one has a different photosynthetic chemical in it and that's why it's a different colour. But we're growing this and taking maybe 30 litres of this out every day, to pour into the krill as their food.

Nick

So, these are live versions of what we just saw on the photographs on the wall down the corridor.

Rob

Exactly. This is a live culture of the Antarctic sea water.

Nick

A question has just come in from Christine, asking what about krill and climate change? Are they likely to be affected by climate change?

Rob

Yeah, we believe they will be because krill are living in one of the areas that is showing the greatest hot spots for warming that we've seen on the planet so far. And krill really do rely on having that ice and that phytoplankton where they're expecting it when they need it - when they hatch out from eggs and they need to start feeding when they get to the surface. So, it really is the big question for krill.

Nick

Okay. Well, here we are Rob, we are with the krill and do you want to tell us a tiny bit about what we're looking at here, because for people looking for the first time, they might look quite small. But in krill world, are they reasonably small animals?

Rob

No, these are actually enormous krill on the world scale. These are one of the biggest of the 85 species. But what's really staggering about krill is not just their size, the species, but the biomass, which we think is up around maybe 500 million tonnes.

Nick

What does biomass mean? I don't know what that means, Rob?

Rob

If you happen to weigh all of that krill material, that's how many tonnes of krill you have. And if you think about your average family car weighing a tonne, imagine 500 million cars weight of krill - staggering amount.

Nick

So, a question from St James School in Cygnet in Tasmania, is how many actual krill does that mean? Are you able to give an estimate of that?

Rob

Well, one krill is about one gram. So, I'm going to leave it for them to do the maths, rather than doing it on Facebook live and getting it wrong. But 500 million tonnes, and it's one gram per krill, for an adult krill.

Nick

And over here in the tank, we're looking down at a small darker brown pool over here. What is that and why are the krill interested in swimming around it?

Rob

Okay, so this is a 24-hour feeder. These krill have been feeding this morning. You can see their guts are quite dark in the middle, that's all the phytoplankton that they've concentrated out of the water with those front legs, filtering down to three micron. They're such efficient feeders, and they've thrown that all in there and they're packing it in tight. But this is extra food, because in the ocean you don't get fed at 10:00 each day, when the public servant comes in, you get fed all day long, if you can get access to the food. Krill actually swim down to depth during the day to escape visual predators, things like penguins and seals. And at night they come to the surface to eat the phytoplankton which is where the light is. We have some of those things happening here, all of the lights are in time with the Southern Ocean, and so forth.

Nick

Well of course, the public servants here at the Antarctic Division come in a lot earlier than 10:00 in the morning, Rob. But tell us a bit about the research you're doing with the krill here, and especially I think in relation to climate change.

Rob

Okay, so the main piece of climate change work we're doing isn't probably the bit most people think about. When most people think of climate change, they think of a warming planet, but there's also what's referred to as the other carbon dioxide problem. And that is that all of this carbon dioxide that we're putting in the atmosphere is dissolving down into the ocean. Now every year about nine billion tonnes of carbon dioxide dissolves in the ocean. When it does that, it reacts with water to form carbonic acid, so the sea is becoming more acidic, it's heading towards neutral, it's meant to be alkaline, and it's starting to drop. And what we've shown here in the lab by breeding these krill here and producing eggs in the lab, and exposing them to different levels of carbon dioxide - we've been able to show that if we did nothing to mitigate our emissions of carbon dioxide, by the end of this century only half the krill that hatched today would be hatching in the Southern Ocean in certain areas around Antarctica, and these are some of the hotspots for where krill reproduce and breed.

Nick

Now that's really important research and that's done here, and that's one of the real reasons we need a sophisticated aquarium facility to do that kind of work, I guess.

Rob

Yeah. Doing that sort of work on the ship is possible, but it's very difficult and you've got to meet the right krill on the right day, with time to stop and do it.

Nick

So, running an aquarium like this is a bit more challenging and sophisticated than the average home aquarium, and we're just going to walk through now into the plant room where the hard work goes on to circulate and clean up the water. What are we looking at here, Rob?

Rob

Okay, so all of this equipment is fairly standard aquaculture technology. The unusual bit of course is the water starts at zero degrees and then we heat it to 20 before we filter it. That gives us much better rates of gas transfer and ammonia removal. This is a foam fractionator or protein skimmer. What's happening here is we're introducing micro bubbles in here, which are attaching to dissolved organics in there, and dragging them out the top because they're buoyant. And this looks remarkably like the foam you'll see washing up on the beach, because it's exactly the same thing – when a wave breaks at the beach, it micro bubbles the water and it drags the natural organics out of there. So, this is just a means of recreating what is normally done by bacteria in the ocean, and the biogeochemical cycle, quickly in the lab, so we can keep more krill, feed them a sensible amount, in what is really a tiny volume of sea water – it's about 30 tonnes of water in here, every hour and a half run through here and re-surf.

Nick

So, it must be working pretty well because I know your krill live for a very long time here. What's the longest you've been able to keep individual krill alive for?

Rob

We've kept krill alive for up to ten years in the lab.

Nick

Ten years?

Rob

Yes. So, we think probably five to seven years is typical in the Antarctic, because something's going to eat them. If you get to be an adult krill, you're a lucky krill. From the moment they are spawned as eggs, they are prey for so much, and so many different creatures.

Nick

And I know you're very proud of this little thing we've got here – well, quite a large thing here. So, this is a special tank, I know you and the team here have designed to be able to show people krill and move it around. How does it actually work? It looks like it's just a great big lump of ice in a tube of water.

Rob

It's exactly how it works in fact. This ice in here is just standard party ice in a chamber in this tank, and it is keeping these krill cold. But the trick is that the centre core here is filled with a super salty brine. It's down at minus six degrees, so all of the heat that is getting dragged in through here –

Nick

Rob, I know that we've got some school children watching here at the Antarctic Division today, and – they're asking us, can krill shrink? And these kids obviously know quite a bit about krill. So, do you want to answer that question?

Rob

Yes, because I don't know many other animals that can shrink, so you're bang on there. Krill can shrink. If you take all food from krill, you can shrink it down from a large size back to a juvenile again. They'll also sexually regress – they'll lose their sexual characteristics and go back to looking like a juvenile. So, what krill are doing here is showing extreme adaptation to the loss of food in winter, because in winter the sun is not there, so the phytoplankton aren't growing. So, krill switch to chasing around zoo plankton and doing other things, but they can also shrink if they get really desperate. It means they're alive and well, and ready when that phytoplankton comes back, the sun's out, the phytoplankton goes off, and boom goes the eco-system, and off go krill coming in to eat it. So yes, shrinking is a trick, and it makes them the most successful crustacean in the Southern Ocean today.

Nick

So, Rob, a really tough question from Denise, what do krill taste like?

Rob

What do krill taste like? Well, I'm sorry krill, but you do taste pretty good. There's a big fishery for krill, it's the biggest Antarctic fishery now. 300,000 tonnes a year and you can buy krill in Australia in things like fish fingery-type products, and also krill oil is a big thing. But if you just get some krill straight out of the net, fry it up with some garlic, it's fantastic. By itself, it's fine but it's a bit plain. But they do have a high level of fluoride in the exo-skeleton, so if we just ate them non-stop, we'd actually get fluoride poisoning from the high level. Whales and penguins have an enzyme to break it down. So, be cautious about how many krill you eat.

Nick

Thanks Rob. And we're very cautious about how much is caught in the ocean because we want them to be there for a long time. Thanks for joining me on this tour. We're going to leave you now with our lovely krill tank here, and thanks so much for joining us here at the Antarctic Division.

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