This man was feeding the manatees carrots. They are vegetarians.
West Indian Manatees can grow to 13 feet and weigh over 3000 pounds. They are shy and completely harmless. Manatees are believed to have evolved from wading, plant eating mammals and share ancestry with elephants. Most manatees found in the US spend the winters in the warmer waters of Florida, but can be found up into Virginia and the Carolinas and west to Louisiana in the summer. They also can be found in coastal and inland waters of Central and south America.