I'm with Pete on this one. The owner is working for a set rate and he is making money(usually good money) or would not be in the business. I would tip his mates as they are probably working for minimum wage and working hard most days for it. I would expect that for the money paid for the day the captian or owner should be working hard to put you on fish at every moment.
When you have a great day on the water you'll tell a few people, when you have a bad trip with little results or energy put into it you'll tell everyone you see and and bad travels alot faster then good news.
Now with all that being said my hat goes off to those in the business. I've have had many tough days on the water and was thinking how it would feel to be a guide and the pressure you guys must feel daily to produce. I personally couldn't do it, I feel bad enough when I take friends out fishing for a day and we can't catch anything.