That kind of artifact recovery is generally a no-no on sunken warships. Unlike a merchant vessel or liner, a sunken warship is still considered the property of the country that sent it to sea, hence no recovery of anything from Bismarck, Yorktown, Hood, Yamato, etc. The only exceptions are those expeditions sanctioned by the government in question, and are usually closely supervised by the appropriate naval authorities. Now, if a state no longer exists, the successor state assumes that role: when the French Navy found the wreck of C.S.S. Alabama off Cherbourg, the USN was notified, and since some artifacts from the ship have been raised by the French, the USN has people there to monitor and "advise" when they do so.
Incidentally, the USN has a similar claim to aircraft wrecks, and the Supreme Court has backed them up, so no more recovering downed planes in the Great Lakes and restoring them to flying status (as has happened with a number of F6Fs, TBMs, and even a few Dauntlesses and a Helldiver). If you pull one up, it has to go to a museum approved by the Navy, and any restoration is to static display only-no return to flight, unfortunately.