FYI: the swim lane has been there for years. It's marked by six (or is it eight?) white buoys that clearly mark a long rectangle. The lane lines up between the Cove and the Shores so that about half the distance is boat free. Closer to the Shores, the swimmers are fair game.
If I remember correctly, there's a plaque in Scripps Park overlooking the Cove that describes the underwater park/reserve, including a map. I believe the swim/no boat lane is marked on the map. If you stay north of the second yellow reserve buoy, the swim lane isn't an issue.
I believe the swim lane buoys are taken down during the winter. I don't know if that means the swim lane isn't enforced during the winter but I won't be tempting fate. Now that I think about it, I don't remember seeing the buoys this summer but I've been staying well north of the second yellow buoy.
Anyway, tight lines and stay ticket-free.