Maritime Jobs

Hi, I just moved to the Pacific Northwest after twenty four years in Arizona, and all of the sudden there seems to be alot of opportunity
working on in and around ships, barges, tugs and fishing boats. I dont know a whole lot about this stuff so I was hoping someone here could help.
Where do i get started? I dont know anything about certificates or licenses that may be required. So how do i get a job on a boat? Is there a union contact
I need to get in touch with? I live just outside of portland oregon and would consider a career somewhere in this industry, any advice?
Any help you guys could give me would be great