Herring clarification

[Double Hall]

I know there is an off limits for river herring, but that ocean herring are catchable. I'm finding loads of herring in the harbor and am clueless as to whether it is legal or not. I don't think it is as simple as "i didn't catch in the river, so it must be ok to use", but honestly not sure what the differences of the two are. Last thing I want to do is catch illegal 7" fish.

Thanks for any help