Smily,
I haven't found a tuna charter on the North Coast, but have experience with two charters out of Depoe Bay.
Joan-e Charters, (800) 995-3866,
http://www.joan-e-charters.com/ And
Tradewinds Charters, (800) 445-8730,
www.tradewindscharters.com/
I tried to get out two times this year and both trips were canceled due to weather.
Good luck and let me know if you find a charter further North.
Here is a good place to start...
http://www.salemhomeplace.com/pages/.../fishlist.html
Please email me and let me know what you find.
Tight lines,
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Live to Fish
Fish to Live