The response I got from a DNR rep about this was yes you can fish in a marina, no they can’t stop you, but do you really want to deal with someone like that in that situation.
You can call the sheriff and the DNR. Its better to have them explain the laws to them, even though I am sure they are aware of it.
Here is what I would do. If you are being constantly harassed to where it interferes with your enjoyment or even becomes a safety issue, but you really want to fish in there, back out of the marina, make the call and wait.
If the person was passive about it, I’d tell him the law says I can and I welcome him to call the sheriff/DNR. If someone was irate and aggressive, I would take the former approach.
I agree it needs to be instilled in these idiots that they don’t own the water in the marina. If enough people keep confronting them, maybe they will give up. Some of the jerks need to be told.
Also it is better when dealing with someone who is not threatening or more passive to have them make the call. These are the sort of issues where if someone has to come out like the DNR or Sheriff where the guy calling is wrong, the DNR/Sheriff will not be happy with them.
Lastly, it might not be someone who works in the marina doing this. I bet a lot of times it is the slip owners.
Watergate Marina has a no fishing inside marina sign as you go in. I guess it is not illegal to post a sign like that, even if it is invalid. They are hoping to convince those who don’t know.