Shorty,
If only it were that simple...removing dead trees, I mean. It probably does help, but it does not stop them.
They prefer standing dead timber for R&R, but I don't have any dead trees over water, never have had any, and have always been plagued by cormorants. They just don't overnight on my ponds, which they would probably otherwise do with dead trees present, but they do just as much damage in terms of fish predation, nonetheless.
Removing the dead trees will help prevent roosting birds, but does not prevent or even discourage, as best I can tell, visitation at my place. They use piers, fish feeders, and any other vertical things on which to deposit their presents after processing fish through their systems.
You can usually set your watch by them...arrive between 7:45 and 8:15 in the mornings, and if undisturbed, leave by 2:00 in the afternoons. If you weren't present during those times, you wouldn't even know they had been there...except when you observe hundreds of fish trying to hide under a pier to escape predation and other fish struggling to survive the body piercings.
Remove the dead trees, but don't be surprised if it does not eliminate the problem.
