There are supposedly yabby banks on the ocean side of Causeway Lake in Yeppoon too, and herring/bony bream can be easily caught in the harbour if you throw off the wharfs (at Rosslyn Harbour).
Happy birthday!
I hope you catch some good fish Kat. Here are some very old reports from the area, but they may help with location if you plan to fish from Yeppoon -
Cheers Hamish