So, the trusty Australian Museum website has some info here and a short video.
It usually lives in freshwater and mature eels migrate to the sea to spawn. Young eels return to freshwater to live.
They grow to about 1m length, which this one was close to. So I guess this was a mature eel heading off to spawn. We do have a river quite close to us, but this eel was definitely washed up on the beach.
I wonder if the rough weather got it? Or was it old age? Or did a fisherman play a part?
So much stuff is washed onto the beach after rough weather. Most of it rubbish, but there are heaps of soft corals, shells, stones and all sorts of things we don't get in calm seas. It makes a walk on the beach a photographic smorgasbord :)