According to the news release the increase to 4 coho only applies to the buoy 10 fishery which ends at tongue point. Since chinook is closed in bouy 10 but open in the ocean if you go outside and get a chinook then you CANNOT fish at buoy 10, you are pretty much regulated to the ocean limits. If you have no chinook in the boat then you can put 4 total fish (coho) in the boat in any combination. Meaning up to two from the ocean and 2 from buoy 10.
The reasoning behind the chinook limits is to keep people from catching them at buoy 10 and tagging them as they came from the ocean.
Here is a link to the news release.
Hope this helps.
Jim
ODFW News