So, you lost all your guns in a boating mishap. As said above, you've reported them as lost to the proper authorities to keep yourself off the hook if one shows up in a crime and to officially get your name removed from them.
Then, miracle of all miracles, you snag one while fishing. I hope you go to the same authorities and report the recovery, else there could be strong grounds for prosecution on filing a false police report. (Especially if the rest of your lost "collection" turns up in your possession.)
And, by the way, if you collected from your insurance company for your “loss”, the guns no longer belong to you. They belong to the insurance company and if they’re not turned over, add insurance fraud to the list.