depends when in sept. there is a good chance that it could have been the kings that are going to the creeks at the far end of the lagoon or some of the silver that go to the same creek.
If they were the kings, good luck. Those things usually get caught with buzz bombs in the side.
The silvers on the other hand will take flys but not as readily as other fish in the south sound. Try something like a karluk flash fly or some hareball leeches and maybe some bait fish patters.
Good Luck,
Justin