Was up there earlier this year (October), mainly fished off broadbeach. There was a huge gutter running across the entire beach, and this was opposite First Avenue. Caught a few thumper bream (one pushing 50cm) as well as plenty of dart, and a few whiting. The whiting were on worms and everything else caught on pippies which are easy to catch fresh on the low tide. The spit breakwall is okay if you can cast out far enough as there are some whiting, trevally and bream and mangrove jack if lucky enough, but if you can't get out far enough expect to snag up a fair bit haha. Not sure of the Nerang River but I'm sure that would have your typical estuary species in it.
Cheers,
Tom