Don't forget to barter a bit. As they are not through the cruise lines, you should be able to get them to lower their prices a bit. -hedge on that $70 per hour additonal charge especially.
I live in a tourist port in America, where everything is more expensive...and our 1/2 day, 4 hour deep sea fishing trips are only $59 each. -no other surcharges, for larger chartered boats (20-50 people). A full day is like $90.
A fully chartered smaller boat for 6 people is usually ~$600-$800 for the whole day. That is $100-$133/each total for 8 hours, which sounds like what they are offering. That's what you would pay for just 3 hours with them.
If that is just bottom fishing, that is way over priced! Of course, if it is heavy sport fishing, like for sailfish or shark, then that would be more justified -in my opinion only.
Of course, if you are landlocked and eager to fish, you will pay a fortune for the opportunity! haha -I know I probably would if I lived inland! That is just one reason why I had to live at the beach! I too am an avid fisherman! We even have our own boat. :) Too bad everyone wasn't in port much longer, or I could take it over to the host hotel, which is right on the water, and take folks for rides!
~Bunny