Getting to know Cape Fur Seals

Getting To Know The
Cape Fur Seals of Namibia

1. How well do we know our Seals?

We spend most of our days with seals. In our rescue videos, we make a point to highlight entanglements and raise awareness of the plastic crisis. We talk very little about the species itself. We might not be scientists, but we thought it a good idea to share our knowledge of these cute and curious animals.

2. Introducing the Pinnipeds!

Our Cape Fur Seals belong to a group called Pinnipeds, just like the Sea Lions, Elephant Seal, Leopard Seal and even the Walrus. They all have different features and are subdivided into three families, the True seals, Eared seals and the Walrus.

True Seals have ear holes and no external ear flap, and they can dive up to 2 hours. True Seals cannot rotate their hind flippers and they appear to be wobbling on the beach with their short front flippers. The biggest True Seal is the Elephant Seal and can weigh up to 4000kg. Eared Seals are generally smaller than True Seals. They have ear flaps, and their long flippers allow them to walk and run on land.

In Namibia, we only have Cape Fur Seals. Every once in a while, we get a single visiting Elephant Seal, and even a Leopard Seal has been spotted here before.

3. Fur Seal or Sea Lion?

Cape Fur Seals look more similar to Sea Lions than True Seals. They share many features, but Cape Fur seals have much thicker fur than Sea lions. Their dense and waterproof underfur made for more desirable pelts, leading to Cape Fur Seals nearly driven to extinction in the early 1900’s!

Sea Lions have a shorter and wider nose, and shorter ears and flippers than the Fur Seals. The largest Sea Lion (Stellar Sea Lion) can reach up to 1000kg, whereas the largest Fur Seal (Cape Fur Seal) can attain a maximum of 350kg.
At OCN, we are happy we get to rescue Cape Fur Seals, and not Sea Lions. We would need a much bigger net!

4. Natural Habitat

The Cape Fur Seal is endemic to Southern Africa. You can find them anywhere between Southern Angola and South Africa’s Algoa Bay, including Namibia’s coastline. Cape Fur Seals live in groups of a few dozen up to over two hundred thousand individuals at Cape Cross.

Up to 2.2 million seals are estimated to cover a coastline of 2800km, 1,5 million of them in Namibia. This number has been stable for the past years, suggesting that there is plenty of food for all of them, and that they have reached their natural carrying capacity.

Cape Fur Seals are semi-aquatic. They mate, rest and breed on land, but they hunt at sea. Big seal bulls spend months at a time at sea and only return to shore to mate.

5. Breeding

We have roughly 40 Cape Fur Seal breeding colonies along the Southern African coast. Most of them are based on islands, only 8 of them are on the mainland. Females usually have their first pup at the age of 5 or 6. Young males can reach sexual maturity at about the same age; however, it will take 10 to 12 years before they reach their full adult size to allow them to defend a breeding territory successfully against other seal bulls. Pelican Point and Cape Cross are both breeding colonies and we often see bulls fighting over females. We need to stop our disentanglements for a few weeks when seals start giving birth.

A Cape Fur Seal give live birth to a single pup between late November and December. She will nurse her baby until she has the next one, exactly one year later. Seal mothers go to sea to hunt for food and leave their pups behind with other newborns. Those so-called “creche-groups” are overlooked by other mothers who are currently on shore, and they will defend all newborns from birds, jackals, and other potential predators. Mothers might have to stay away from their babies for several days until they have fed enough to return to their babies. Seal bulls start mating with the new mom only a few days after she gave birth – females are almost always pregnant!

Cape Fur Seal Bulls stay at sea for most of the year where they hunt and rest. Bulls usually return to shore in October and November to establish their territory and herd as many females as possible into so-called “harems”. A big alpha seal bull will claim up to 50 or 60 seal cows for himself and he will prevent other bulls from mating with them. Bulls survive off their blubber reserves during this period and can lose up to a third of their body weight before they return to the ocean. They spend the entire breeding season, from October to January, defending their territory and harem, with no time to go to sea and hunt for their dinner. This behaviour is unfortunately also the reason why they are easy targets for seal hunters, seal bull genitalia get exported to China.

Cape Fur Seal pups are born between November and January. They stay with their mom for the first few days until she goes off to feed herself. When she comes back, mother and baby find each other among thousands of other pups through smells, calls and barks. Seal milk is very rich and nutritious, the pup can stay behind for a few days without starving. Seal pups start swimming after a few weeks, but it takes a few months until they can catch fish for themselves. They stay reliant on their mothers’ milk until the next newborn takes over. Seal bulls are not involved with their offspring, they go back to sea as soon as mating rituals have concluded.

6. How do Cape Fur Seals hunt?

Seals have excellent underwater vision; their eyes are perfectly adapted for the ocean. They hunt during day and night. Most adult Cape fur seal bulls spend their lives at sea and only return to shore during breeding season. They follow the fish and can cover well over 100km per day. They are often seen hunting in groups and can dive up to 200m to catch fish. Females do not stay away from their pups for longer than 6 days at a time, meaning their range is much smaller than the males. It can have devastating impacts on breeding colonies when fish are not within this range!

7. What do Cape Fur Seals eat?

Fish! A fully grown male can eat up to 10% of his body weight per day while out at sea. Cape Fur Seals also eat octopus, crustaceans and even the odd seabird, but horse mackerel, sardines, hake, lantern fish or gobi are their first choice. Cape Fur Seals have sharp and pointed teeth to grip slimy food, but small fish are swallowed whole, headfirst, so that the scales don’t scratch their mouths.

Seals are often seen near fishing vessels; as a result, they are being blamed for stealing “our” fish. We argue that it is the other way round: we are stealing their fish! Overfishing has dramatically limited food availability in the ocean over the past decades. Luckily, commercial fish only makes up about 15% of a seal’s diet.

8. How Cape Fur Seals are protecting our fish stocks? Seals are Apex predators, meaning they are on top of the food chain and they keep population dynamics balanced between large and small fish sizes and species. It is simple: seals prey on large fish, and large fish prey on small fish. If large fish have no more predators, they will eat all the small fish until there is none left. Seals are believed to protect fish stocks by eliminating medium sized predators!

3. Fur Seal or Sea Lion?

10. How do Cape Fur Seals sleep?

Cape Fur Seals seem to be able to sleep anywhere! When on land, they sleep like most other mammals. They always keep their guards up for potential predators nearby. While out in the ocean, they lie on their sides and rest one half of their body and brain at a time. The awake half of their brain will stay alert enough to warn them of any danger. They stay afloat by paddling with one flipper at a time. They sleep with one flipper in the air, which warms up and allows warmer blood to recirculate - a bit like a solar panel!

9. How do Cape Fur Seals keep warm?

Cape Fur Seals can only be found in cold water. They have two layers of coarse hair. When the outer guard hairs are wet, the dense, fine inner hairs remain completely dry. Air trapped in this layer provides additional insulation. It's the fine hair that made their fur so popular, nearly leading to their extinction. Seals also have a thick layer of fat under their skin to keep warm, the so called “blubber”. Besides causing infections, entanglements can impact a seal’s ability to keep warm.

11. Are Cape Fur Seals endangered in Namibia?

We have good news for once: Cape Fur Seals are NOT endangered in Namibia. For the past decades, total seal numbers have been stable with an estimated one million seals along the Namibian coast alone, suggesting that we have reached the maximum number of individuals that the environment can carry and sustain. Nature regulates itself, if left alone. Why do we bother with disentanglements if seals aren’t endangered? Because plastic pollution is not natural, and we can’t stand seeing animals suffer due to human negligence.

12. Why are there so many Cape Fur Seals in Namibia?

In a nutshell, Cape Fur Seals have found their paradise. A healthy seal colony is an indicator of a healthy marine ecosystem with sufficient fish stocks and normal oceanographic conditions. The Benguela Marine ecosystem is one of the most productive coastal upwelling zones in the world. Without natural predators, seal numbers are regulated by breeding sites and fish availability. Although overfishing has been a major problem in this area in past decades, fish stocks continue to support sea birds, larger fish and marine mammals, including the Cape fur seal.

13. Are there too many Cape Fur Seals in Namibia?

Absolutely not! Nature regulates itself, if left alone. Recently, individuals from the fishing industry have claimed that we have too many seals in Namibia, and that the animals are responsible for declining fish stocks. We strongly disagree. Seals mainly consume fish that is not commercially targeted, and those fish stocks are strong and healthy. Only commercially targeted species are declining, suggesting that the fishing industry might have been overfishing, meaning they catch fish faster than stocks can replenish. We can’t blame seals for our own mistakes!

14. What is the annual seal harvest?

The annual harvest, also known as cull, is the commercial killing of seals for their fur, meat, oil or genitalia. For many years, the Namibian government has issued annual quotas for 60.000 seal pups and 8.000 seal bulls to be commercially hunted. Seal bulls get shot with a bullet; seal pups get clubbed to death with a metal pipe meant to smash a pup’s head.

Thanks to an import embargo for reasons of animal welfare, seal products have been prohibited in the EU since 2009, effectively destroying the market for seal fur products. This embargo has saved hundreds of thousands of seal pups from a terrible fate! Seal bulls remain a commercial target for their genitalia.

16. Visit our seals!

Namibia is the best place in the world to see Cape Fur Seals! Cape Cross has the largest accessible seal colony in the world, visitors can see more than 200 000 animals congregated together at this incredible spot. Countless tourists flock to Namibia every year to visit these cute and curious animals. Watching them swim, dive, and interact with each is so entertaining and enjoyable that a huge seal sightseeing industry has emerged in Namibia, providing countless jobs in the tourism and hospitality industry. Some seal cruise operators even collaborate with scientists and researchers to help gather data on our local seal and dolphin populations, behaviour, and habitats!

15. It’s all in the poop!

Seal poop (scat) helps us learn more about what is happening beneath the ocean surface. We can learn more about fish species when analysing scat. For example, by analysing ear stones, also known as otolith. Different fish have ear stones ( also known as otoliths) that are different in shape and size, so scientists can find the otoliths in the poop of our seals to see what kind of fish they are eating. A seal’s poop can reveal if they have eaten large or small fish, and how many of each. We often help collect scat samples (bags of poop) from remote seal colonies to help the scientists from Ministry of Fisheries to get an idea of fish movement, fish population density and general marine ecosystem health.

17. In a world without seals....

… the marine ecosystem would suffer. Seals are important contributors to nutrient cycling in marine ecosystems. Their excrement contains valuable nutrients that help support the growth of plankton, which forms the base of the marine food web. Without seals, the food chain would be interrupted from the top and bottom, as other marine animal species fight over new dominance. Seals have a massive impact on ocean health, so let’s protect them!

Namibia: Ocean Conservation Namibia Trust, PO Box 5304, Walvis Bay, Namibia

USA: Ocean Conservation International, 8 The Green, STE A, Dover , DE 19901

Getting To Know The Cape Fur Seals of Namibia

Getting To Know The
Cape Fur Seals of Namibia