Atlantic Tarpon

Atlantic tarpon evolved approximately 18 million years ago and are one of the oldest living fish. It has been recorded at up to 2.5 m (8 ft 2 in) in length and weighing up to 161 kg (355 lb). Males rarely weigh more than 100 pounds. A tarpon is capable of filling its swim bladder with air, like a primitive lung. This gives it a predatory advantage when oxygen levels in the water are low. In appearance, it is greenish or bluish on top and silver on the sides. The large mouth is turned upwards and the lower jaw contains an elongated, bony plate. The last ray of the dorsal fin is much longer than the others, reaching nearly to the tail.

Since tarpons are not commercially valuable as a food fish, very little has been documented concerning their geographical distribution and migrations. They inhabit both sides of the Atlantic Ocean. Their range in the eastern Atlantic has been reliably established from Senegal to the Congo. Tarpons inhabiting the western Atlantic are principally found to populate warmer coastal waters primarily in the Gulf of Mexico, Florida, and the West Indies. Nonetheless, they are regularly caught by anglers at Cape Hatteras and as far as Nova Scotia, Bermuda, and south to Argentina. In the Gulf of Mexico there are two distinct populations divided by the Mississippi River Delta. Atlantic tarpon are highly migratory and often cross international boundaries. This introduces challenges in management and conservation. Scientific studies indicate schools have routinely migrated through the Panama Canal from the Atlantic to the Pacific and back for over 80 years. Since tarpons tolerate a wide range of salinity and are opportunistic feeders, their migrations are limited only by water temperatures. They prefer water temperatures of 22 to 28 °C (72 to 82 °F); below 16 °C (61 °F) they become inactive, and temperatures under 4 °C (39 °F) can be lethal. A large tarpon community is found in the Rio San Juan and Lake Nicaragua. In the Pacific a population has become established in Costa Rica. …

The Atlantic tarpon's most significant predators are sharks and humans. The diet of the Atlantic tarpon changes as the fish grows with those in the leptocephalus stage absorbing nutrients directly from the water, those in the juvenile stage eating zooplankton and other small prey, and adults primarily consuming fish, crabs, and shrimp.