yes, it's fake. But here is the long version of the story as to why it was in my garage (it isn't anymore).
Years ago someone decided to put the shark into a nearby lake basically to give new divers something to see. To do this, they put a lawn tractor innertube in the fiberglass shark, attached two steel cables and secured it to concrete blocks. Once in the lake the inner tube was inflated enough to float the shark so it appeared to hover about 5' off the bottom. Over the years the innertube lost air, and the shark ended up on the bottom. Last year we went to try and "fix" the shark but ultimately blew the inner tube...oops! So, we removed the shark and took it back to my place where we installed pool noodles for flotation, then over to another house where it was repainted, and then was put back in the lake.
Obviously this is not relevant to almost the entire thread, the exception being the one line I quoted from Pete
...and yes, it did freak out some neighbors