Since man began taking fish from the ocean, they have used natural occurrences and eventually man-made technology to help them find fish.
Before modern fish-finder sonar, grouper fishermen would pack a heavy brass bell with soap and drop it to the bottom on a line. They would bounce it a couple of times on the bottom and retrieve it.
If sand was stuck to the soap, they would move on. If pieces of rock or fragments of coral were embedded in the soap, they knew they were over good grouper habitat and fish there.
There’s a place in the Golfo Dulce near Pavones that, most of the time, the fishing isn’t very good. But if you’re there in a certain moon phase, on a certain tide, you will catch nice 10-pound-plus corvina one right after another.