The hunt is on. Fifty miles northeast of Isla Mujeres in the Gulf of Mexico, sailfish prowl through blue waters.
Frigatebirds hang like arrows above the sea, dipping down now and then to grab a meal. Following their lead, Anthony Mendillo, sportfishing guide and expert sailfish chaser, steers the Keen M toward the flocks. Sure enough, below the birds a school of sardines hundreds strong moves as one, flashing in the sun with each turn. Dozens of long shadows orbit the ball of frantic fish: the hunters.
Sailfish and sardines are migratory and widely distributed, with populations in multiple oceans. But from January into June, Istiophorus platypterus and Sardinella aurita meet fish to fish in this stretch of sea. For predator and prey the continental shelf here makes ideal habitat. Plankton-rich shallows, nourished by rivers draining the mainland and ocean currents pushing between Cuba and the Yucatán, promise ample food.
The hunt seems almost mammalian. Sailfish—which often travel in loose groups—clearly join forces. Males and females alike circle the prey, pushing the school into tighter formation, and taking a few bites in turn. Each forward rush is punctuated by a startling flare of the dorsal fin, which more than doubles the hunter's profile.