@dlochner, I can only speak for the Raymarine Lighthouse MFDs and as reported in the Raymarine forum thread:Dig deeper into the software for the AIS and CP. There is often a way to filter the targets to eliminate those that are not moving or not a danger. When transiting NY Harbor, I turned off the AIS as there were so many targets I couldn't see the chart!
If the description of the target is a number or seemingly random 2 or 3 letters it may be an EATON, Electronic Aide to Navigation. These targets are actually buoys and the the AIS signal is not broadcast from the buoy, rather it is broadcast over land based stations which cover many more miles.
" Unfortunately, hiding the stationary targets does not help. Doing this seems to only hide the stationary targets on the chart but they still appear in the AIS Targets list and continue to count toward the 100-target limit. For example, if I look at the AIS target list I see a large number of targets showing 0.0 kn SOG (even though the hide stationary targets option is set to "on". And if I press the "show on chart" button for any of the 0.0 kn SOG vessels, the chart zooms to an empty patch of water (e.g., a slip in my marina) where the boat is tied up but no AIS target is shown on the chart, because it's hidden."
I believe as more and more AIS transmitters come in use this is a major shortcoming in the Lighthouse software.