Yes, you are right on all accounts anon. I worked the Gulf of Mexico oil and gas fields in the 90's. The procedure for getting a job on the crew boats was pretty much the same, but the pay was far more predictable than fishing. Boats were leased to the drilling company on a daily rate, so our pay rates were fixed based on position and experience. Started as a deckhand, worked my way up to engineer.
I loved every minute of it and earned a decent living doing it. However, like any good thing, it doesn't last forever. The near shore fields played out and the oil companies moved out into the deep water. The boat I worked on couldn't handle the tonnage required or make the speeds needed to get out to the deep water rigs.
Smaller fleets such as the one I worked for were bought out by the bigger ones, who had or were building boats that could make 25-30 knots. Towards the end it was getting hard to find hands. The reason native citizens don't want to work on the ocean is it is perceived as dangerous work, and requires 2-3 weeks away from home every month. Soy boys don't want to do it, wives and girlfriends don't want them gone that long, and there are better paying (but less satisfying) jobs ashore.