You will find a list of air-to-air claims for American patrol aircraft during WWII here:
http://aces.safarikovi.org/victories...e.aircraft.pdf
These included claims by PB4Y but also PBY and possibly PBM. But still you will find in this list some claims for JU 88 C-6 and Do 217 over Biscay Bay by VB-103 and VB-105, using PB4Y, so the answer of your question is: almost all PB4Y kills were scored in the Pacific, but not all of them.