I was able to reattach the fin back onto the side of the shark before then reconstructing my bow and pouring the other half of the mold.

After pouring the second half of the mold, there was some leakage around the edges of the box so that finding the parting line of the mold was somewhat challenging. However, I was able to cut through one of the sides and find where it was at to then take the mold apart. 

I did lose the same shark fin that had been detached before and there was no way to repair the clay piece.