There is a way to tell which ones are not there - they're gray. About 1 in 30 are orange (active), the rest are gray (inactive). It only shows one orange one in Herring Bay. I can say that the orange ones in Chester River correspond pretty closely to the ones I've observed there in the past few years.There are nothing like that many pound nets on the bay, and no way to tell which are, and are not there. It shows ~20 pound nets in Herring Bay are there have never been more than 2 in the 10+ years I've sailed from there. From what I see, it looks like maybe 1 in 30 or less shown on the chart were actually there in recent years.