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The Southern Ocean around Antarctica is home to approximately 7,500 species of marine animals. These fascinating creatures range from penguins and seals to krill, glass sponges, and colossal squid. 

Antarctica is governed by the Antarctic Treaty, which reserves the continent for peace and science. The Southern Ocean is governed by a treaty known as the Convention on the Conservation of Antarctic Marine Living Resources that is dedicated to a precautionary, ecosystem-based approach to management. Both treaties have been signed by nations that have an interest in Antarctica. 

FISHERIES IN THE ANTARCTIC REGION

Now, all fishing activity in the ocean around the Antarctic Continent is strictly regulated by the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR). As its name implies, the Convention is focused on conserving Antarctic ecosystems. Fishing is allowed, but with important restrictions:  any fishery can only have a very limited impact on the ecosystem and should be managed in a way that minimizes risk to ecosystems. This precautionary, ecosystem-based approach ensures that decisions about fishing consider the needs of other species.  

In the CCAMLR Area, companies from different nations come each year to fish for Patagonian and Antarctic toothfish, mackerel icefish and Antarctic krill.

Krill Fisheries

The abundance of Antarctic krill is intimately tied to seasonal sea ice conditions, climate, and ocean currents. Key breeding areas of krill are located in the Western Antarctic Peninsula, where the fishery operates. This area has experienced major warming over the last 50 years, and as a result, the extent and duration of winter sea ice are being reduced. This represents an important challenge in the management of the krill fishery. 

The Antarctic krill fishery started in the early 1970s. It peaked in the late 1980s with catches up to 500,000 tonnes per year, by USSR and Japanese vessels. From the mid-1990s onwards, the krill catch dropped to under 100,000 MT per year. However, there has been a renewed interest in fishing for krill due to a growing market for nutritional supplements and fishmeal. In 2014, 290,000 tonnes of krill were harvested in the South Atlantic Sector. In 2014, approximately twelve vessels fished for Antarctic krill. Norway, Korea, China, and Chile are the biggest krill fishing nations.

Although the krill population is large, many predators hunt for krill in the very same areas (sectors) where krill fishing occurs. To ensure that the fishery does not harm these other species, CCAMLR has set limits on the krill fishery. 

Aker BioMarine Antarctic, one of the founding partners of the Antarctic Wildlife Research Fund (AWR), is a Norwegian company operating two fishing vessels and is the biggest operator targeting krill by volume. Aker BioMarine’s krill products are used in human health and animal nutrition products. The krill fishery involves significant investments in specialized vessels, research, and development. AkerBioMarine’s long-term interests depend on strong precautionary management and up-to-date knowledge of the krill population. 

The partners that make up AWR believe that in creating the fund, we will contribute to filling the gaps in knowledge about krill that is needed for responsible management of the fishery. The projects funded by the AWR will help resolve scientific uncertainties about krill and the broader ecosystem, providing better information for making fishery management decisions.

Plankton

The Southern Ocean winter may be harsh, cold, and dark, but the spring and summer bring a sudden burst of activity. 

The seasonal phenomenon of the reduction in sea ice extent and the subsequent growth of massive blooms of plant plankton, drives the life cycles of many Antarctic marine species. In spring, these blooms form in the open ocean as warming temperatures cause sea ice to break up and melt. The disappearance of the ice provides the sunlight required for photosynthesis. The subsequent increase in productivity directly or indirectly supports the entire foodweb, from seafloor creatures to birds and mammals. 

Plankton is part of a complex Antarctic system in which nutrient-rich currents interact with seafloor features, sea ice, and ice shelves to generate the conditions necessary for plant growth. The formation of large Southern Ocean polynyas, open-ocean regions surrounded by ice, is an integral part of the ecosystem. As the ice disappears from these areas, nutrients in sea water combined with sunlight results in plankton blooms. 

The polynya in the Ross Sea, the largest on earth, contributes to the Ross Sea being the most productive stretch of ocean around the Antarctic continent. This productivity ultimately makes it possible for 38% of the world’s emperor penguins to breed in the Ross Sea region. 

Indeed, plankton blooms are especially critical in Antarctica because plankton is required to support the huge swarms of krill that in turn feed squid, fish, seals, whales, penguins and even a species of starfish. Plankton is a food source for many other small species such as copepods that are in turn consumed by larger organisms. Furthermore, many species breed in Antarctica during spring, increasing their need for food to feed growing offspring. Disruptions due to climate change can affect these seasonal patterns of sea ice extent and plankton growth, and therefore can have a major impact on Antarctic species. 

The Antarctica krill

Krill have a complicated life history, changing size, shape and habitat as they grow. They mature at two years old and can live for up to eleven years. Adult krill are capable of living anywhere in the Southern Ocean – from the very surface layer to the seafloor, and from inshore areas to the deep open ocean. Larval and juvenile krill stay close to sea ice and feed on algae that grow on the underside. 

The krill population is large and they reproduce at high rates. Consequently they are preyed upon by a range of animals including seals, penguins, whales, fish and squid. It is also subject to a commercial fishery, internationally regulated by CCAMLR.

Krill have a complicated life history, changing size, shape and habitat as they grow. They mature at two years old and can live for up to eleven years. Adult krill are capable of living anywhere in the Southern Ocean – from the very surface layer to the seafloor, and from inshore areas to the deep open ocean. Larval and juvenile krill stay close to sea ice and feed on algae that grow on the underside. 

The krill population is large and they reproduce at high rates. Consequently they are preyed upon by a range of animals including seals, penguins, whales, fish and squid. It is also subject to a commercial fishery, internationally regulated by CCAMLR.

Fish

Antarctica boasts a diverse range of fish species that are supremely adapted to their unique and harsh environment. 

Many Antarctic fish species, particularly in the Notothenioids suborder that makes up the majority of Antarctic fish species, make their own antifreeze that enables them to survive Antarctica’s cold waters. 

Members of the icefish family lack hemoglobin, the protein that most vertebrates use to transport oxygen in their blood. Instead, they are able to absorb oxygen directly from the surrounding water. 

Some fish species are adapted to live their entire lives near the deep seafloor and lack swim bladders, the gas-filled organs used by most fish to adjust their buoyancy. Other species have developed special fat reserves to provide the neutral buoyancy they need to lay their eggs directly under the sea-ice. 

Each Antarctic fish species plays an important role in the food web, many as prey items for animals like seals, whales, colossal squid and penguins.

The unique life histories and habitat use of most Antarctic fish are not well understood. Some of these species share a common set of characteristics – they are slow growing, late maturing and long lived. Whether exploited directly or taken as bycatch, these characteristics make populations of these fish species highly susceptible to being overfished. Because these species are particularly well adapted to the unique conditions of the Antarctic, they are expected to be very sensitive to small changes in climate as well as sea-ice loss.

Birds 

Able to withstand the harshest climate on earth, the birds of Antarctica are like no others. From the wandering albatross that can soar for hours and has the largest wingspan of any living bird, to the flightless emperor penguin that may travel up to 120 kilometres to reach open water to forage, Southern Ocean birds have mastered the challenges of polar living.

Though the Antarctic may seem inhospitable to life, for birds it has a number of advantages. The greatest is the lack of predators on land. Though penguins may encounter predatory seals and whales in the water, there are few threats to adult penguins on land. Skuas, another type of bird, may attack and kill chicks of penguins and other birds, but they cannot challenge adults. Petrels may prey on adult penguins, however. Flying birds like albatrosses and petrels similarly face few threats in the Antarctic. 

The Albatross

To rear their chicks, some seek ice-free areas and build nests of pebbles on the ground, while others prefer to nest on rocky cliffs and ledges, like the Antarctic petrel. Adélie penguins are famous for stealing rocks from each other’s nests. These pebbles have been stolen back and forth for hundreds of years. Emperor penguins forgo nests entirely, and keep their eggs on top of the males’ feet, where a special area of featherless skin called a brood patch warms them. Regardless of the type of nest, penguins, albatrosses and petrels are all devoted parents, incubating eggs and raising chicks for several months. Some albatrosses may fly for thousands of kilometers to obtain food for their offspring.  

In addition to relative safety from predators, the abundance of food sources during the austral spring and summer makes Antarctica a perfect place to raise young. Krill, fish and squid are all important food sources for flying birds as well as penguins. As described above, some birds also eat other birds, and may consume carrion from dead seals and birds. Access to prey becomes particularly critical during the breeding season. If they have to travel too far to find food, the chick might starve. 

During breeding, many Antarctic birds gather in large colonies, some of which are among the largest bird colonies in the world. The Antarctic may seem like a peaceful place, free from the noise of human activity, but a large penguin colony full of squawking birds fighting for the best nest location is anything but serene. Nevertheless, these tough survivors exist in a delicate balance with their environment, and small disturbances can have a great impact. 

The main threat to Antarctic birds is climate change. Changes in the distribution and extent of sea ice may affect breeding or prey availability. Climate-related changes in weather may increase precipitation, which can harm chicks that haven’t developed their adult waterproof feathers yet. In addition, climate change, ocean acidification, and human activities in the Antarctic could cause changes to the food web and bird habitats. Some species may find it challenging to adapt

Whether soaring or swimming, the common thread among these birds is the important role they play in Antarctica’s intricate food web, both as predator and prey. Not only do they provide a glimpse into the great biodiversity of this region, they also provide invaluable insight into the effects of climate change and human activity on ocean health.

Penguins

Penguins are perhaps some of the most popular and best-loved of all birds. They appear throughout human culture, and are featured in children’s books, in magazines, cartoons, and in the movies; indeed, March of the Penguins was one of the highest-grossing documentary films of all time. When people think of penguins, they think of the Antarctic, and imagine a pristine wilderness occupied by numerous sleek, fat, well-fed penguins.

When encountered in the wild, penguins can seem querulous, angry, and argumentative. After breeding penguins moult their feathers they are anything but sleek. In fact, they cannot enter the water again until they have grown new feathers.

There are 18 species of penguins and they do not all live in the Antarctic. Many species are classified as Endangered or Vulnerable by the International Union for Conservation of Nature. These at-risk populations live mainly in South America, Africa, New Zealand, or in the sub-Antarctic. 

Seven species of penguins are found in the Antarctic: Adélies (Pygoscelis adeliae), chinstraps (Pygoscelis antarctica), gentoos (Pygoscelis papua), king (Aptenodytes patagonicus), emperors (Aptenodytes forsteri), macaronis (Eudyptes chrysolophus), and southern rockhoppers (Eudyptes chrysocome).

Penguins spend the majority of their life at sea, diving for small fish, squid, and crustaceans, such as Antarctic krill (Euphausia superba), on which they feed. They return to land to reproduce and breed in colonies. The largest known penguin colony is on Zavadovski in the South Sandwich Islands where a million pairs of chinstraps breed annually. Feeding so many penguins requires enormous amounts of marine prey.

In the Antarctic and sub-Antarctic, Adélie, chinstrap, gentoo, macaroni, and emperor penguins depend upon Antarctic krill, particularly during the breeding season. Understanding how penguins find their food and how they compete with seals, whales, and other seabirds, as well as how fishing activities impact their prey sources, is vitally important if penguin populations are to thrive.

SEALS

At times, Antarctic seals may seem to be lumbering, inactive mounds of blubber and fur, rolling around aimlessly on the ice. In reality, like many Antarctic animals, they are highly specialized marine creatures able to thrive in one of the most extreme environments in the world.

There are only six species of seals that live in the Southern Ocean: the crabeater (Lobodon carcinophaga), leopard (Hydrurga leptonyx), Weddell (Leptonychotes weddellii), Ross (Ommatophoca rossii), elephant (Mirounga leonina) and Antarctic fur seals (Arctocephalus gazella). However, they are present in enormous numbers. In fact, the crabeater is possibly the most numerous large mammal on the planet, after humans.

Seals are part of the suborder of mammals called pinnipeds (which means fin-footed). Awkward on land, but impressive in the water, they have special muscles to close off their nostrils when they are diving and swimming. They can also slow their metabolism and heart rate during dives to conserve energy and air, and their lungs and blood vessels are especially efficient in absorbing oxygen.

Nevertheless, Antarctic seals are a diverse group. Some, like the elephant and fur seals, live in colonies where aggressive males maintain control over multiple females. Weddell and crabeater seals are somewhat less social, although they do gather occasionally in large groups, and leopard and Ross seals are solitary. Their diets and hunting strategies also vary. The slightly misnamed crabeater seal has incredibly unusual teeth that allow it to eat lots of tiny krill (a crustacean but not a crab). Weddell seals dive to depths of hundreds of meters and often catch large fish. Scientists have observed these seals bringing uninjured Antarctic toothfish to the surface, but could not explain how they did this. Antarctic toothfish can reach 2 meters in length, while Weddell seals range from 2.9-3.3 m. It is possible that they use sonic bursts to stun and catch them, a clever way to enjoy a nice toothfish dinner without a lot of effort.

Though they may be excellent predators in the water, Weddell seals aren’t the top seal predator in the Southern Ocean. That title belongs to the leopard seal, which not only eats fish and krill, but penguins and other seals. And they have occasionally attacked humans.

WHALES

Ten species of whales are found in Antarctic waters. Filter feeding baleen whales include the largest animals that have ever lived – the blue whale (Balaenoptera musculus) and the fin whale (Balaenoptera physalus). The blue whale can grow up to 24 meters and weigh as much as 84 tons, making it the largest animal on earth.

Together with the humpback (Megaptera novaeangliae)and the minke (Balaenoptera bonaerensis) they feed predominantly on krill. Krill often form vast swarms or schools in the Southern Ocean. These aggregations can stretch for up to 20 kilometres and can contain over a million tonnes of krill in densities over 10,000 animals in every cubic metre - the largest concentrations of animal life in the world. Baleen whales have evolved special fringed plates of keratin (called baleen) in their mouths that allow them to swallow large mouthfuls of krill from these swarms, and filter out the unnecessary sea water. The sei (Balaenoptera borealis)and the Southern right whales (Eubalaena australis) are also baleen whales but their diet consists of much smaller crustaceans.  

Antarctic toothed whales include the killer whale or orca (Orcinus orca), which is the Southern Ocean’s top predator. They hunt in packs and eat penguins, seals, and the young of other whales. The much larger sperm whale (Physeter macrocephalus) is also a toothed whale and feeds on fish and squid at great depth.

Many Southern Ocean whales are migratory, and head to tropical waters during the Antarctic winter. Calves are born in these warmer waters. Every day a newborn blue whale drinks 200 litres of milk that has 9 times the fat content of human milk. This enables a calf to double from its birth size of 2.5 tonnes in just 6 months, enough to take on a migration of thousands of kilometres when the whales return south in the austral spring to feed. A young calf will accompany its mother for several years on the annual migration. Females will not mate again until their calf is independent. 

Over 1.3 million whales were taken from Antarctic waters last century. It is estimated that there were over 225,000 blue whales before their exploitation; today there are fewer than 10,000.

Many whale populations are now recovering because they have been protected from hunting since 1986. The recovery of some, like the blue whales, is still uncertain and numbers are still critically low. Others, such as humpbacks, are undergoing a population boom–but their numbers are still below historical levels.