I went out of Westport last August and had a great trip aboard the Goldrush. We did the one day trip, left at 0300 and returned around 7PM. We were 45 miles SSW, actually off of Wilapa Bay, I have the Lats and Longs although the fish were moving several miles a day and i'm sure it varies from year to year.Check out this link, it may answer a few of your questions.
http://westportcharters.com/tuna.html We started out trolling in the morning and when that was not working Kevin just found the birds, and we were in the fish for the next 7 hours pretty much non stop. I do not think I could have caught salmon on the way home if I tried, I brought 17 fish to the boat and another guy got 21. We ended up bringing 11 home a piece. I had all mine fileted on the way in and brought home just over 100 lbs of tuna.
Best of luck I will go again with Kevin next year when I finish all the Tuna I have now.
NEN