Surrounded Description
The most common billfish is the sailfish. In the Atlantic, they average 35 to 50 lbs. and 6 1/2 feet in length. They are usually found alone or in pairs at certain times of the year in certain places.
Sailfish form schools in order to surround or "ball" bait. It is then that their great dorsal fin or "sail" comes into play. With their sails erect, these billfish circle the bait which forms into a tight ball where they become easy prey for these predators as they dart in and feed in orderly fashion.
Like most professional fishermen, I have seen this sight many times right here off my home waters of Stuart, Florida.