In the video below, Captain Kevin Beach, of the Mexican Gulf Fishing Company (MGFC) captured a massive bait ball in the Gulf of Mexico.
Pogies formed a column just beneath the water surface, and swam together in a concentric movement for as far as the eye can see. Bait balls are a defensive tactic deployed by forager fish and some small pelagic species. Bait balls like the one shown in this video are common in the Gulf of Mexico off Venice, LA, from October through January each year.
Defense mechanism that it is, the maneuver still attracts predators, and charter fishing captains, keen to put their customers on big yellowfin tuna.