My dad is one of 38 million commercial fishermen! Do you like to fish?
I do enjoy fishing, I never knew there were so many commercial fishermen! Are commercial fishmen different than other kinds of fishermen?
Yes. Commercial fishermen work in the industry where others just fish for recreation. 
I see, I bet they bring in a lot of money worldwide
They sure do! Fishing for food has existed since the Mesolithic period. People have always loved to eat fish!
That is a long time! Do they fish for any other types of marine life?
Sometimes fishermen gather shellfish! That's a little different than throwing a line into the water.