The Importance of Krill

Ian Somerhalder Foundation

What are Krill?

Out of all the water dwelling creatures living in the world’s oceans, Krill are commonly unrecognized at mention, but their importance far surpasses that of most, if not all, of its sea-dwelling neighbors.

Krill are tiny, pink, semi-transparent crustaceans with large black eyes and are usually around only two inches in length. Amazingly, their digestive systems are usually visible and are often seen as a bright green color due to the phytoplankton, tiny single-celled plants, and algae that they eat. They can survive up to two hundred days without food, and typically, they can live between five and ten years. There are eighty-five known species of Krill. The Antarctica Krill are the largest, with the densest populations living in the waters around Antarctica where the oceans contain few contaminants and are far more untouched than in other areas of the world. Krill gather in swarms so dense and widespread during certain periods of the year that they turn the surface of the ocean a pink-red color and can be seen from space.4 This serves as a defense mechanism for them; if a predator were to come along, the predator would have a difficult and confusing time picking out any single Krill for themselves. 4 But Krill also tend to spend their days in the deep depths of the oceans hiding from predators, surfacing at night to feed.1 The worldwide population of Krill has been estimated to outweigh the human population of the world. 2

Krill are considered to be one of the most abundant and successful animal species on earth, and they provide the driving force behind the marine ecosystems of the planet. 3 Many consider Krill to be the “fuel” that the planet’s marine ecosystem runs on; without them, most of the life in the Antarctic would begin to disappear.

How important are Krill?

Most of the animals of the Antarctic – seals, whales, and squid – depend on Krill! They are also a major part of the diets of a variety of marine animals including fish, birds, and whales. 

The Decline of Krill

Unfortunately, like many other sea dwelling creatures, the number of Krill is declining. Certain studies have shown their numbers to have decreased by eighty percent since the 1970s. Some believe that the decline in Krill is one of the reasons some penguin species are also declining in number. 10 Scientists also worry that the decline in Krill will make it difficult for Baleen whales to repopulate to the numbers they were once at. 2

There are many reasons for the Krill’s decline. The rising sea temperatures, a result of the greenhouse effect, compromises Krill’s their major food source, phytoplankton. As sea temperatures rise, the pattern by which the phytoplankton blooms is altered. Additionally, the loss of ice due to rising sea temperatures also means the loss of ice-algae.1 Rising sea temperatures put Krill and animals that feed off of them at risk. 

Also, the thinning of the ozone layer increases the amount of ultraviolent light that reaches the Antarctic and serves as another threat to the Krill’s survival. 

Protecting Krill

Today, 400,000 tons of Krill are caught annually. Krill oil is marketed as a dietary supplement because it contains high amounts of Omega-3 fatty acids. It is also used to treat high cholesterol. However, even if alternatives are found and utilized for Krill oil, over half of the Krill caught are actually used for fishmeal or animal feed. 

Thankfully, Krill are protected under a fishing treaty that was enacted in 1981. The Convention on the Conservation of Antarctic Marine Living Resources sets limits on the number of Krill that can be caught, taking into consideration the needs of the ecosystem.7 The treaty also protects the Antarctic ecosystem from expanding fisheries and helps in the recovery of great whales and overfished fish species. 

The Antarctic Krill Conservation Project also works to protect the Krill population. It is comprised by a network of organizations that work together to promote Krill conservation and the conservation of the Antarctic marine ecosystem. They do this by adopting the following principles:
(1) Utilizing “a highly precautionary, effective and integrated ecosystem-based package for Antarctic krill management that ensures that functional relationships in the Antarctic ecosystem are maintained, and that krill abundance and availability for predators is not compromised, taking full account of climate change and other relevant environmental factors”;
(2) Preventing “the expansion of the fishery until these measures have been approved”;
(3) And by “formally recognize[ing], through appropriate commitments and actions not limited to CCAMLR or the Antarctic Treaty System, that the Antarctic's unique character as the last great wilderness, as home to exceptional concentrations of biodiversity including penguins, whales, and albatrosses, and its critical role in global environmental processes, requires special conservation actions, including but not limited to protected and closed areas.” 9