The remarkable eels of Sydney’s Centennial Park

By Australian Geographic 21 January 2019
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They can live to be 100 years old and must make a grand journey at the end of their lives to New Caledonia to complete their life cycle.

THE SPECKLED long-finned eels (Anguilla reinhardtii) of Centennial Park in Sydney live what at first may seem modest lives. Carnivorous animals, they feast on plentiful insects, small fish, even small birds, and serenely weave their way through the park’s various ponds from day to day.

But what many Sydneysiders don’t know, is that, once of age, many of these animals embark on a perilous 2000 km journey all the way to New Caledonia to breed. This trip, for the eels, is a journey home.

It is from these spawning grounds that each of their lives began. “Every eel in the park is born in the ocean,” says Sam Crosby, who works in the education precinct of the park and is in charge of informing people about these remarkable eels.

“The story of the migration is one I like telling because it links us to the wider ocean… they’ve been migrating for thousands of years. The story is also just quite beautiful, they’re going back to where they were born.”

The beginning of their lives is spent 10km deep in the tropical waters of New Caledonia. As larvae, they drift along the currents of the Pacific Ocean towards the temperate waters of the east coast of Australia in search of fresh water.

Those of Centennial Park make their way through the waters of Botany Bay, travelling through stormwater channels and entering through the parks’ Musgrave or Kensington ponds.

Most will make the journey home at 40 years of age. In autumn each year, when water levels are higher thanks to recent rain, the eels glide through the ponds – exiting the very same way they entered – to make their way home to breed and then die.

“It’s a circular story,” says Sam. “Even though the eels die after laying their eggs, you get the next generation coming through, ready to make their way to Sydney.”

For some, however, the journey is a bust. “Since their arrival the landscape may have changed [or the water levels are too low] and so they become landlocked and can’t return. Unfortunately, they will never go back to breed, instead they live out their days [which can amount to 100 years] in the local landlocked waterways.”

According to Sam there’s still much we don’t know about the eels – and when it comes to the journey itself, we don’t even know the half of it. “I would love to see some research around tagging methods so we can follow their journey; exactly how long it takes and how many make it,” she says. “I’m sure there’s a lot of peril they experience on that journey.”