The location of the find will tell us a lot about the possibilities, as bones don't tend to move around on their own. So can you tell us where it was found?
Like Chris I would go fish from the appearance. I can't really see it in your photo but I think fish vertebrae have a concave depression at the ends but mammals have flatter ends. My memory is a bit vague on that though - it was 30 years ago after all. I may treat myself to a tin of salmon for lunch and check.
The Bone was found on Lammermoor Beach 8 K's South of Yeppoon in QLD.
And now that it was mentioned it dose look a bit like the tined Salmon Bones but just larger.