I guided for twelve years after I retired, so I might have a biased perspective. I think that a 15 to 20 percent tip is in order IF the guide did his job, which means:

Did he deliver on what he advertises or told you on the phone or in person? Was his equipment in good working order? Did he have all the euipment he needed to perfom the tasks? Did he catch fish for you or give you a reasonable chance to catch fish? Was he pleasant to be with? Did he work hard to deliver.

I didn't always expect a tip, but was pleased to get one. I wasn't a high profile guide at all, mostly servicing clients from the Alaska lodge where I guided in the summer, and fishing on the Columbia and the O.P. under the best of conditions. My clients were very good tippers because I kind of high graded them from the lodge. and knew what they were like before I invited them.

People want to catch fish, of course, but what they want most is to have a good time. If you have a good time with the guide, I think they deserve a tip in the range of 15 to 20 percent. If you have a world beater type day that will be among your best ever, dig a little deeper in your wallet.

Just a thought: I have a friend who went to Tofino a few years ago, and asked me about tipping his salmon guide there. My buddy has a few bucks. I told him to introduce himself to the guide with a $100 dollar handshake, then tell him what he wanted to do for the day, and say "Please just take care of us". It really worked, and I'll tell you why from the guides perspective: In Alaska working in a lodge, you might get the same guests 3, 4, or 5 days in a row. If they decide not to tip you until the end of the 5 day trip, you, the guide begin to wonder if you will even get a tip? If they tip you well at the end of the first day, you can't wait to see them again the next day, and will bust your butt for them. It's just human nature.