Small crab, big crab : the Antarctic krill Euphausia superba is technically quite small (and not a real crab). But in the Antarctic food web, the animal is at the top. Virtually every other Antarctic species, from fish to penguins to blue whales to leopard seals, has the crustacean on its menu. In the meantime, humans (again) also belong to this group. To learn more about Euphausia, the Australian Antarctic Division has launched a months-long expedition to the Southern Ocean, using the latest camera technology to swim among swarms of krill.
“What really delighted us was to capture the individual in stereoscopic vision”
Rob King, Kril expert Australian Antarctic Division
From the Australian research vessel Investigator, the system consisting of several stereoscopic cameras was launched and brought down to a krill swarm. At a depth of between 30 and 60 metres, the camera was able to take the first images of krill after the ship was brought out of the zone. The first stereoscopic live images of a krill swarm were taken, which also filled the researchers on board with enthusiasm. “What really delighted us was to capture the individual in stereoscopic vision re-engaging with the swarm, which will allow us to analyse the rules for swarm integration in 3D,” explains Rob King, krill expert at AAD. With this success, work has now been taken out of the laboratory and into the field for the first time, he continues.
Krill is not just a crustacean, but the most important food source in Antarctica. From large blue whales to small fish, all want the little decapod crustaceans, which are only 6 centimetres in size and weigh 10 grams. Practically all Antarctic penguin species, numerous seabirds and also seals feed on the pink-appearing crustaceans every summer. In the meantime, however, also the human being again joined the krill-hunt. The Commission for the Conservation of Antarctic Marine Living Resources CCAMLR is responsible within the Antarctic Treaty Area for the regulation of and compliance with Antarctic krill fishing quotas. How much krill there is actually is not known. It is estimated that up to 500 million tonnes of krill could be floating in the Southern Ocean. More cautious circles rather assume about 100 million tons. Project TEMPO (Trends of Euphausids near Mawson, Predators and Oceanography) aims to shed more light on the mystery of krill. In addition, more recent data will be collected in CCAMLR Division 58.4.2 as the krill fishery is expected to resume there. The aim should be a sustainable fishing policy for the small crustacean.
CCAMLR sets krill fishing quotas and fishing regions based on research estimates. At present, this amounts to around 620,000 tonnes in the entire area between South Georgia and the Antarctic Peninsula. But in fact less than that are fished. The latest published figures show around 440,000 tonnes of krill caught. But the pressure is mounting. The major fishing nations at present are Norway, Russia, Korea, China, Japan, Chile, Poland and Ukraine, according to CCAMLR. Their products then find their way into the world’s aquacultures and food production and even into cosmetics and wellness production (krill capsules, krill oil, etc.). Many countries see “big business” in this, as krill is seen as a seemingly endless resource. And this despite the fact that researchers have been sounding the alarm for some years now: ocean acidification and higher water temperatures coupled with dwindling sea ice in one of the main zones of Euphausia superba are putting the small animals under pressure.
To relieve some of this pressure from the Antarctic Peninsula and at the same time meet the increased demand (and thus minimize illegal fishing), the region near Mawson Station was also opened (Region 58.4.2). But no one has fished there for more than 25 years. AAD’s research aboard the Investigator is intended to fill this gap. “These ocean deployments give us an understanding of how krill orient themselves in swarms and how they form swarms which is key to better predicting the biomass of krill – or how much krill there is – in a study region,” explains Rob King. To this end, the role of the deep sea in the life of krill will also be investigated. Because according to the latest research, Euphausia not only loves swarming but also is a deep diver. As we said: Big crab, little crab (still not a real crab, though).
Dr Michael Wenger, PolarJournal
Link to the website of the Australian Antarctic Division: Krill matters
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