That's a great question that many people don't pause to ask. And, as you indicate, one applicable to a number of passages. In this case, I think it's a situation of general applicability, but also with a distinct application to those in the ministry. What I mean is this: the foundational fishermen, if you will, will always be the apostles. Carrying on that apostolic ministry are those who are called to the office of pastor. Their job, we might say, is fishing. Yet there are elements within that vocation that are applicable to everyone. For instance, we are all witnesses, teachers of the truth, students of the Word, etc. AND we all fish in our different vocations, that is, we all bear witness in this dark and chaotic world to the Christ who comes to rescue us from evil and sin. In short, while the whole vocation of some is fishing for men, within our respective vocations, we do so as well.