Tarpon (Megalops atlanticus)


The largest member of the small Elopidae family, the tarpon is one of the world's premier saltwater gamefish. Also known as the Atlantic tarpon, this species is sometimes scientifically identified as Tarpon atlanticus.

It is a relative of ladyfish and of a similar but much smaller species, the Indo-
Pacific tarpon (Megalops cyprinoides), also known as oxeye tarpon or oxeye herring. In prehistoric times, there were many more species of tarpon; today, there are just these two.

Other Names

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

Identification

The tarpon's body is compressed and covered with extremely large platelike scales and a deeply forked tail fin. Its back is greenish or bluish, varying in darkness from silvery to almost black. The sides and the belly are brilliant silver. Inland, brackish-water tarpon frequently have a golden or brownish color because of tannic acid.

The huge mouth of the tarpon has a projecting, upturned lower law that contains an elongated bony plate. A single, short dorsal fin originates just behind the origin of the pelvic fin and consists of 12 to 16 soft rays (no spines), the last of which is greatly elongated. The anal fin has 19 to 25 soft rays. The lateral line is straight, with a scale count of 41 to 48.

Size/Age

Most angler-caught Atlantic tarpon are in the range of 40 to 50 pounds, but many from 60 to 100 pounds are encountered. Fish exceeding 150 pounds are rare in the western Atlantic.

The all-tackle world record is shared by two 283-pound fish, one caught in 1956 at Lake Maracaibo, Venezuela, and the other in 1991 at Sherbro Island, Sierra Leone. The Florida record for tarpon caught with conventional tackle was a 243-pounder from Key West in 1975.

Some Atlantic tarpon live as long as 55 years. Most of the tarpon caught in the Florida fishery are 15 to 30 years old.

Life history/Behavior

In May and June, Atlantic tarpon in the western Atlantic begin gathering together in staging areas near the coast in preparation for the journey to their offshore spawning grounds. Here, schools of tarpon may be observed swimming in a circular, rotating motion.

This behavior, known as a "daisy chain", may be a prenuptial activity that prepares the fish for spawning. The actual exodus to the offshore spawning areas is probably triggered by lunar phases and tides.

Although no one knows exactly where tarpon spawn, tarpon larvae only a few days old have been collected as far as 125 miles offshore in the Gulf of Mexico. Spawning in Florida occurs mainly in May, June, and July.

The eggs hatch into larvae called leptocephali. These bizarre-looking creatures have transparent, ribbonlike bodies and slender, fanglike teeth. The leptocephali drift with the currents toward the shore, reaching estuarine areas within about 30 days.

By the time the larvae reach these inshore areas, they are about an inch long. At this point, they begin an amazing transformation in which they lose their teeth and begin shrinking in length, winding up as miniature versions of the behemoths they will eventually become.

One particularly remarkable facet of tarpon physiology is the fish's ability to breathe both underwater and out of the water. When dissolved oxygen levels in the water are adequate, tarpon breathe like most fish, through their gills.

When oxygen levels are depleted, however, they can also breathe by gulping air, which is then passed along to their highly specialized swim bladders. The swim bladder functions as an accessory lung and even resembles that organ, with its spongy, highly vascular tissue. The swim bladder can also be filled with air as needed to help the fish maintain its desired depth in the water.

Although tarpon can tolerate water of various salinities, they are vulnerable to cold snaps and become stressed when water temperatures fall below 55°F. Adults can often seek refuge from the cold in deep holes and channels.

Food

Tarpon often travel in schools with other tarpon and are opportunistic eaters that feed on a variety of fish and crabs.

Distribution

Because tarpon are sensitive to cold water, their range is generally limited to temperate climates. Atlantic tarpon have been reported as far north as Nova Scotia and also 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. Atlantic tarpon from the western Atlantic have also emigrated through the Panama Canal and become established in the eastern Pacific; large specimens have been caught along the western Panamanian coast and in the vicinity of some rivers.

Although scientists believe the western Atlantic stock is genetically uniform, they have observed regional differences in behavior and size. Tarpon in Costa Rica, for example, are generally smaller than Florida tarpon, and Costa Rica tarpon spawn throughout the year, rather than seasonally, as Florida tarpon do.

Habitat

Tarpon are most abundant in estuaries and coastal waters but also occur in freshwater lakes and rivers, in offshore marine waters, and occasionally on coral reefs. Adults often patrol the coral reefs of the Florida Keys.

In Costa Rica and Nicaragua, anglers frequently catch tarpon in freshwater lakes and rivers miles from the coast. Although tarpon do migrate, little is known about the frequency or the extent of their travels. Tarpon captured in Florida have later been recaptured as far west as Louisiana and as far north as South Carolina.
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