I have seen people using the jetty near my beach home to fish. I always thought it was because it allowed them to walk out into deeper water, so it would let them have access to more fish than simply fishing from the shore would.
I didn't think about fish actually hanging out and making homes inside the gaps in the rocks. It's kind of sad that the place where they feel safest is actually one of the most dangerous for them.
It almost seems like the jetty is serving as fish bait. The fishermen take advantage of the fact that the fish have their guard down.