Latin name

Megalops atlanticus

Other names

Silver king, Atlantic tarpon, cuffum; French: tarpon argenté; Italian: tarpone; Portuguese: camurupi, peixe-prata-do-atlântico, tarpao; Spanish: pez lagarto.

Identification

The body of the tarpon is elongated and contracted, covered with large major scales and a deeply forked caudal fin. The head is rather large. The mouth is large, oblique, and the teeth on the jaws are small and sharp. The back is greenish or bluish, its color ranging from silvery to almost black. The sides and belly are silvery. In inland, brackish waters, the tarpon often have a golden or brownish color due to tannic acid. The tarpon's mouth has a protruding, upturned lower part, which contains an elongated bony plate. The single, short dorsal fin originates just behind the beginning of the pelvic fin and consists of 12-16 soft rays (without spines), the last of which is strongly elongated. The anal fin has 19 to 25 soft rays. The lateral line is straight, with 41 to 48 scales. The scales are large.

Distribution

It is found along the east coast of America from Cape Cod to South Brazil, and in the tropical waters of West Africa from Senegal to Angola. Because tarpon are sensitive to cold water, their range is usually limited to temperate climates. Atlantic tarpon are found as far north as Nova Scotia and off the coast of Ireland, although they prefer tropical and subtropical waters. In the western Atlantic, they are most common from Virginia to central Brazil, and throughout the Caribbean Sea and the Gulf of Mexico. The Atlantic tarpon from the western Atlantic also migrated through the Panama Canal and settled in the eastern Pacific. Large specimens have been caught along the western Panamanian coast and near some rivers. Although scientists believe that the West Atlantic stock is genetically homogeneous, they have observed regional differences in behavior and size. For example, tarpon in Costa Rica tend to be smaller than Florida tarpon, and Costa Rican tarpon spawn throughout the year rather than seasonally like Florida tarpon.

Habitat

Keeps near shores, often in front of river mouths, and enters brackish and fresh water. Tarpon are most abundant in estuaries and coastal waters, but are also found in freshwater lakes and rivers, in marine coastal waters, and sometimes on coral reefs. Adults frequently patrol the coral reefs of the Florida Keys. In Costa Rica and Nicaragua, anglers commonly catch tarpon in freshwater lakes and rivers miles off the coast. Although the fish migrate, little is known about the frequency and extent of their travels. Tarpon caught in Florida were later recaptured as far west as Louisiana and as far north as South Carolina.

Size

Most Atlantic tarpon caught by fishermen are between 40 and 50 pounds, but fish between 60 and 100 pounds are also found. Fish weighing more than 150 pounds are rare in the western Atlantic. The world record for all tackle is held by two fish weighing 283 pounds, one caught in 1956 on Lake Maracaibo, Venezuela, and the other caught in 1991 on Sherbro Island, Sierra Leone. Florida's record for tarpon caught on conventional tackle is a 243-pound fish caught in 1975 in Key West. Some Atlantic tarpon live up to 55 years. Most tarpon caught in Florida are between 15 and 30 years old.

Life history and Behavior

In May and June, Atlantic tarpon in the western Atlantic Ocean begin to congregate in staging areas off the coast, preparing to travel to their offshore spawning grounds. Here, groups of tarpon can be observed swimming in circles and rotating. This behavior, known as "daisy chain," may be a mating act preparing the fish for spawning. The actual exodus to offshore spawning areas is probably caused by lunar phases and tides. Although no one knows exactly where tarpon spawn, larvae that are only a few days old have been collected 125 miles offshore in the Gulf of Mexico. Spawning in Florida occurs mostly in May, June, and July. Larvae called leptocephalus hatch from the eggs. These bizarre creatures have transparent, ribbon-like bodies and thin, fang-like teeth. Leptocephals drift in currents toward the shore and reach the estuary in about 30 days. By the time they reach these coastal areas, they are about an inch long. At this point, the larvae begin a remarkable transformation in which they lose their teeth and begin to shrink in length, becoming miniature versions of the monsters they will eventually become. One particularly remarkable aspect of tarpon physiology is the ability of fish to breathe both underwater and out of water. When the level of dissolved oxygen in the water is sufficient, they breathe, as most fish do, through their gills. However, when oxygen levels drop, fish can also breathe by swallowing air, which then enters their highly specialized swim bladders. The swim bladder functions as an accessory lung and even resembles this organ with its spongy, highly vascular tissue. The swim bladder can also fill with air as needed to help the fish maintain proper depth in the water. Although tarpon can tolerate water of varying salinity, they are vulnerable to cold temperatures and become stressed when water temperatures fall below 55 °F. Adults often seek shelter from the cold in deep holes and channels.

Food and feeding habits

Predator. Tarpon often travel in schools with other tarpon and are opportunistic eaters, eating a variety of fish and crabs.

Reproduction

It spawns in spring and early summer. The eggs appear to be benthic. The diameter of discharged eggs is 0.6-0.75 mm. Fertility is up to 12.2 million eggs. After hatching from the eggs, the larvae of the tarpon (leptocephalus) are transparent and ribbon-shaped. After the body length reaches 23-24 mm, it begins to decrease to 14-15 mm and the body shape changes, gradually approaching the body shape of adult fish.