Now that you can speak with the Winterfin, it is time for you to let them get to know you. One of the best ways to do that is to conduct business with them.
The murlocs prize clams over any other object and their only surviving merchant is Ahlurglgr. If I were you, I'd collect a handful of Winterfin clams and give them to him as a gift.
The clams can be found all over down in the trench, as well as across it in the Winterfin village and their caverns.