(21 July 2017) It defies belief that eels, born in the ocean of Vanuatu, 1,500 km from Australia, can be found 500 m up, in a Tamborine Mountain rock pool. Not only that: at the end of their lives they go back to that tropical island to create the next generation.
All local long-finned eels begin their lives, as an egg, in the tropical ocean waters off Vanuatu. They drift in the ocean currents for many years till they approach the shoreline… if they haven’t ended up as dinner or lunch for some other maritime creature (scientifically known as ‘predation events’). The now juvenile elvers or ‘glass eels – they are transparent and about the size of a finger – wriggle and slip, and even crawl overland, their way up the water-courses and waterfalls, to a fresh mountain pond. This is where they spend their entire adulthood of around ten years; they can easily be seen in the rock pools of the Cedar Creek. Towards retirement age, finally the urge to reproduce will strike, driving the eels to return to the very same ocean breeding grounds of their elverhoods… where they will mate and promptly die.
It is even more remarkable that offspring often go back to the specific creek or waterhole where one of the parents spent most of their lives. Recent research shows that detection and interpretation of magnetic fields plays a role in this process, as do genetic factors. Other research shows that the chemical structure of the water of the creek of the parents is in one way or another the indicator for the offspring.
On the Northern hemisphere American eels use the Ocean around Bermuda for the same purpose. Remarkably, the European eel, which is a significant different species, also uses the Bermuda sea for spawning! Our Aussie eels share Vanuatu with Indonesian, South East Asian and Kiwi eels.
This photo was straightforward, as the eel decided to spend a bit of time above water. All that was needed was patience.