Cervantes - Swimming With Sealions

We booked with the Lobster Shack on their Sea Lion Tour . The boat took us out into Jurien Bay Marine Park to the South Cervantes Island, the islands the sea lions occupy. Jumping in, the water was warm and the tide was pleasant ,sheltered by the rocky edges of the island, approximately 2-3m deep it wasn’t long before the sea lions stated to appear over the rocks and into the water.

The Australian Sea Lion

Known scientifically as Neophoca cinerea, is a highly communicative, sedentary sea mammal native to the Western and Southern coasts of Australia. Unlike other marine species, they don’t migrate seasonally. Instead, they remain close to their haulout and rookery (breeding) sites on offshore islands, rocky bays, and sandy beaches, with occasional movement being noted from New South Wales, Victoria, and Tasmania.

Known to have stocky bodies, large heads, small ears, long and tapered muzzles, and short and narrow flippers, the Australian Sea Lion has the ability to walk on all fours (unlike their seal cousins) and swim up to almost 30 kilometres per hour. Adult males and pups are dark brown in colour, with the adults having a mane-like yellow area on their neck and heads, and the pups having a pale crown, whereas the females are instead a variation of grey, silver, and tan tones with darker backs and lighter undersides. Size-wise, adult males measure between 2-2.5m in length and weigh between 250-300kg. Adult females, on the other hand, measure 1.3-1.8m in length and weigh between 61-104kg.



Life Cycle
The female’s breeding cycle spans 1.5 years, giving birth after a gestation period of 12 months to a singular pup between the months of January and June. Sadly, pup mortality is quite common, and sat at 60.2% in 2019. With the females having 2-3 years in between pregnancies, the protection of newborn pups is integral to the conservation of the species.

Over the first year, pups spend their time living alongside their mother, during which they play and join in mock battles with other pups. From then, weaning will begin to take place at around 15-18 months.

After about 4-6 years, females will have become sexually mature, followed by males at 8-9 years. It’s estimated that the Australian Sea Lion’s lifespan can reach up to 25 years.



Habitat and Lifestyle
Endemic to Australian waters, these diurnal species occupy around 50 islands off the coastline, from Houtman Abrolhos to the Pages Islands – the latter of which is close to Kangaroo Island.

In addition to islands, they enjoy residing on isolated bays and sandy beaches in social units of about 10-15 individuals and can move from one subgroup to another depending on their needs. When hunting for food, they can reach depths of over 180 metres and remain underwater for up to 40 minutes. They can also be found on cliffs, thanks to their ability to climb – some of which have reached heights of up to 30 metres!



Diet and Nutrition
Australian Sea Lions are carnivorous beings, fitting into the piscivores and molluscivores subcategories. Their sagittal crest indicates that they have incredibly strong jaw muscles, which helps them to latch onto prey; octopus, blue-throated wrasses, squids, fairy penguins, cuttlefish, small sharks, stingrays, and whiting are amongst the common sealife in their diet.

Great White Sharks and Orca Whales, more widely referred to as Killer Whales, are the Australian Sea Lions’ natural predators.



Mating Habits
Their mating habits are of a polygynous form – each male having a pup with multiple females. Males will guard female social units for up to 4 weeks at a time, and engage in fights with other males to decide who is allowed to breed with the females at that time.



Sea Lion Conservation
Unfortunately, the current population of Australian Sea Lions is dropping rapidly, with the last recorded number of 6500 in 2014 classifying them as an endangered species.

An early catalyst of their population decline was due to their hunting in the 18th and 19th centuries for their skin and oil. Since then, their biggest man-made threat has been gillnets; panels of undetectable mesh that are anchored vertically in the water to trap fish. When fishermen secure them properly, they provide a firm, wall-like resistance that larger marine animals can bounce off of, however in many cases, they are loose enough to trap sea lions, causing them to drown.

Other threats to their population include chemical pollution, noise pollution, oil spills, climate change, a decline in prey and liveable habitat, and diseases brought upon by contamination of their waters.

What’s being done about it? In 2018, their endangered status led to the WA Government establishing protection zones situated around designated breeding colonies, which prohibit the use of gillnets.Read more