A half submersed hand holding baby eels

The eel deal

24 August 2018

Eels get a pretty bad rap! They’re known for being slimy… and not particularly good-looking. Some say eels are just a little bit too snake like……

But eels are remarkable creatures. They make arduous migrations to breed and play a key role in natural ecosystems. So we’re working to nurture and look after them in our waterways.

Don’t fence me in!

Baby eels are called elvers. They’re quite tiny (about 10 centimetres long), and you can fit about 800 of them in a one litre milk carton! But they’re amazing creatures - swimming thousands of kilometres from their birth place off Queensland to our Tasmanian rivers.

Elvers instinctively swim up rivers where they grow into adult eels. That gets complicated when they swim up a river and get confronted with the wall of a hydro dam that’s about 30 metres high.

But our aquatic scientists have come up with a novel solution.

Enter… the elver ladder

A chute full of eels inside a dam wallWe developed a migration pathway for the elvers through the dam wall and out the other side using a specially-designed elver ‘ladder’. Of course, it’s not a ladder with rungs, as humans might think of it… but rather, a special channel running through the dam wall, gently sloping so the elvers can climb both through and upwards to the lake above, with the help of flowing water.

The ladder runs inside the dam wall in an area called the gallery. It’s installed next to the stairs used by operators to access the internal dam wall.

It’s a big ask for elvers to climb such a long way over a slippery surface. So we fitted the ladder with studded matting which stopped the elvers slipping back down.

Once the elvers reach the top of the dam, they fall gently into a holding tank . The tank automatically empties into a pipe leading to the lake several times a day.

Once released into the lake, the elvers will spend around 20 years (sometimes longer) growing in the upstream river system. So getting them there safely is a very big deal, and well worth the effort.

Success with eels and ladders

We’ve set up a successful elver ladder at Trevallyn, and work with the Inland Fisheries Service to support their trapping operation below Meadowbank Dam. If required, we can use the expertise developed at Trevallyn to assist elver migration at other sites.

So far, we’ve managed to assist the migration of millions of baby eels – which will help to support the ecology South Esk River.

We know Tasmanians expect more from Hydro Tasmania than a typical business. When confronted with an environmental or ecological challenge, we’re determined to invest time and funding to  address these challenges. It’s a proud part of our commitment to serving Tasmanians and Tasmania’s precious natural values.

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