I had this same problem but i just went to the main menu and restarted the same raft and it was fixed.
I had something similar happen. my attack animation got disrupted by the shark breaking the board i stood on. i fell in the water and my spear became unusable. moving it around or even crafting another spear did not help. reloading the game fixed the problem.
Thanks for finding out how this bug happens, we will look into it!
I too have experienced this same glitch. I recorded it. Unfortunately I had discoverd it when I pulled my spear out to defend from a shark attack. It seems the spear has taken on the animation set of the fishing rod.