no one wants to leave a ship, still afloat, abandoned; if so the first person to put a cable on board it can claim it as its salvor

Thanks, Bob! Abandonment. That's what I was looking for, pertaining to vessels at sea...just couldn't remember. And all seaman respect that. The other stuff (washed-up debris and broken moorings) I don't know about. Seems to me if the lobster pots have ID then the owners can claim them...even without a special law. But, then again, abandoned boats and ships have registration numbers and other means of identifying ownership, but the law of abandonment still stands there? A curious quandary.