By-catch is the number one danger followed by hunting.
You can make a reservation for a whale watching tour, but not for the whales themselves. Some do guarantee you will see at least one whale or receive a rebate of some of your cost.
Sometimes the whales just like to hide and count the number of tourists that can't understand why the whales aren't leaping into the boat 7x24.
Other times it is the weather or other factors.
But persistence pays off...