I usually don't see them until December, peaks around Christmas, and disappear by mid January when the water temps dip below 42 or so.. or if we have an iced up harbor for a day or 2, they split. They return on warmer offshore currents so the window is tight... you can pick away at some of them that never leave but the majority of them split with the spearing on the Jan full moon..
Is what I have seen anyway.. for what it's worth