Seacliff’s stingrays uniquely ours

If you’ve ever been swimming, stand-up paddleboarding or have just dipped your toes in the water at Seacliff Beach, it might surprise you to learn that you weren’t alone.

Seacliff is home to a cluster of large, mature female stingrays - smooth rays and southern eagle rays - who live in the shallow waters all year round.

While locals have seen the rays for years, Flinders University PhD student Chloe Roberts recently discovered that most are females.

“I tagged 13 rays and only one was male, so from that, we can infer that at least the ones who come close to shore are females, and it could be that the males are in the area, but just further offshore,” Chloe said, who’s been studying the diet and movement of different marine species, including southern eagle rays for the past few years.

Chloe’s study on southern eagle rays is only the second done in South Australia, so there’s still a lot that is unknown about these amazing sea creatures who love coming close to the shoreline.

Although rays can live up to 30 years in captivity, it’s not yet known exactly how old the tagged Seacliff stingrays are or how many live together at one time.

“I’d wager that they probably live about 20-30 years, but we can’t confirm that for sure at the moment,” she said, explaining that the age of a ray can only be determined by measuring its vertebrate after the animal has died.

“Every time one does wash up, we can collect information and samples, and hopefully, in the future, there will be enough samples for a study to be done.”

Chloe says that it’s likely Seacliff’s stingrays stay close to the shore because there is easy access to food, shelter and warm water, which helps with their metabolism and also provides a safe haven for their babies.

Eagle rays give birth to live offspring, potentially several at a time.

“They are completely independent once they’re born….they go off on their own and fend for themselves,” Chloe said.

While Chloe has caught and tagged the rays for her research - with approval from Flinders University’s ethics board - beachgoers are urged not to touch or catch the rays, as they’re not only very strong, they also carry a barb on their tails.

While they’re not considered aggressive animals, they may attack in self-defence if provoked, and the venom from their barbs could be lethal.

“They’re lovely animals, and members of the Seacliff community are very protective of those rays,” Chloe said.

If you have any anecdotal information about the Seacliff population that could assist Chloe's research, please email chloe.roberts@flindersuni.edu.au

Drone photo by James Whitelaw

Fast facts

• Stingrays is a general term for any ray with a barb
• Within our population, there are two main species of stingrays:
  - Southern eagle rays, which have a mottled appearance with pointy fin tips, a small fin on the tail and a blunt snout
  - Smooth rays, which are plain grey with an irregular pattern of small white spots, rounded fins and a pointy snout
• Both have a large hole behind each eye. This is called a spiracle, which allows them to draw in oxygenated water from above their body, so they can breathe even when lying flat on the sea floor. They also use the spiracles to pump water into the sand to hunt for prey
• Their flat shape means that they are specialists in feeding on the sea floor, targeting prey such as crabs, squid and fish
• In marine ecosystems, they play an important role as mesopredators (middle predators), which means they help to control prey populations and provide large predators, such as sharks, with food.
• The smooth ray is the largest ray in Australia. It can grow to 4.3 metres in length, 2 metres wide and weigh up to 350kg