Early autumn in Gippsland: The leaves on the trees change colour, rain increases, the temperature starts to change, and the eels of Gippsland’s rivers and lakes are on the move.
Eel migration is one of the most fascinating natural phenomenon in the world, although little is known about parts of the incredible journey these creatures make.
Here in Gippsland it starts late summer, when mature adult eels living in the calm, fresh water of the region’s rivers stop feeding and begin to travel downstream towards the brackish environment of the Gippsland Lakes.
They journey along the Thomson, Latrobe, Avon, Macalister, Tambo, Perry, Mitchell and Nicholson rivers and arrive in the lakes en masse late-March, before migrating out to sea to in April/May to spawn.
Natural and man-made barriers are no obstacle for the remarkable creatures, which traverse land when necessary, hurtle down dam spillways, slide through stormwater grates, and even manage concrete walls should the need arise.
The eels are driven by instinct to return to the place from which they spawned, believed to be deep in the Coral Sea in the South Pacific Ocean, some 3000 to 4000 kilometres away.
Along the way down the rivers they begin to change colour, lightening from a dark browny-grey, to a light silver.
It is the depth of the open ocean that detail of the eels’ activity becomes scant, with little known or documented about their behaviour at this point.
Silver eels are only rarely caught at sea, leading scientists to believe they disappear deep into the ocean.
What is known is that they only reproduce once before dying, most likely exhausted after spawning up to 20 million eggs some 300-3000 metres below the surface.
The leaf shaped larvae then move through the ocean’s current, drifting, floating and swimming until they reach the east coast of Australia.
As they reach the coast, the larvae transform into small transparent baby ‘glass’ eels, and then remarkably begin to make their own way to the Gippsland Lakes and the rivers from which their parents came.
It is believed the eels receive some kind of genetic imprinting from their parents in order to know where to travel.
As they feed in the brackish Gippsland Lakes, the eels become darker in colour and these juveniles, now called elvers, finally begin their own migratory journey upstream into the rivers to feed and mature for the next 10-20 years, before the process starts all over again.
If you’re out on the Gippsland Lakes this autumn, keep an eye out for the eel migration and perhaps tip your head in respect at the journey that awaits these unassuming, but incredible creatures.
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