From New Caledonia to the Barwon River: tracking migratory eels using satellites

Eels are an important part of Victoria’s biodiversity and Indigenous cultural heritage, yet globally and locally the anguillid eel species are in decline. This is primarily due to:

Habitat decline
Migration barriers
Overfishing
Climate change
Pollution
Parasites

Victoria’s two eel species, the Long-finned eel and the Short-finned eel, migrate over three thousand kilometres throughout their lifecycle. Researchers have been working in conjunction with Gunditjmara Traditional Owners and the Glenelg-Hopkins Catchment Management Authority to track these culturally significant eels since 2019, using innovative satellite technology.

Migratory routes of eels between sourthern Australia and the Coral Sea. Image credit: DELWP

The satellites are attached to adult migratory stage eels to track the distances they travel during oceanic migration, as well as the temperature, depth and light of the surrounding environmental conditions.

So far they have learnt that the eels travel from the south-eastern corner of Victoria to the Coral Sea, where the adults spawn. The eggs and larvae then drift with the ocean currents for around 2-3 years, where they grow into ‘glass’ eels (smaller, transparent eels).

Coral Sea. Source: Toby Hudson (Wikimedia Commons)

The life cycle of freshwater eels. Source: Bruce Mahalski

These glass eels start to move back into estuaries along the Victorian coastline where they develop a darker pigmentation. These larger and darker eels then move into freshwater river systems upstream from the estuaries. The life cycle diagram above shows these different stages.

The Barwon River Estuary where the eels enter freshwater rivers. Photo Credit: The Barwon Estuary Project

These eels are highly important for Victoria’s biodiversity and support commercial and recreational fisheries. Short-finned eels are of particular cultural significance to Gunditjmara Traditional Owners in Western Victoria, where eels traps have been used for thousands of years to capture the eels.

Budj-Bim eel traps World Heritage site in Victoria. Source: https://wec2019.org.au/

It is still not known precisely where exactly the eels spawn in the Coral Sea, however, it is thought to be between New Caledonia and Papua New Guinea at a depth of around 200m. Continuing to increase our understanding of the eel’s migratory route and the conditions they inhabit will improve our ability to protect their local environments and habitats.

Feature image: An anguillid eel swims underwater. Photo credit: DELWP

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