The word "Megalops" translates from the Greek language as "large-eyed". The eyes of Megalops atlanticus are a very prominent feature and aid tarpon in hunting for prey. Tarpon have been known to make thumping noises to communicate with those around them or to scare off predators when they become startled. These noises are produced by vibrations in the swim bladder.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
The effects of catch and release fishing programs on Megalops atlanticus are not yet fully understood. Releasing tired fish may make them unable to recover quickly. Tarpon may then die from oxygen deprivation or become easy prey for predators. Permits are now being issued to anglers who intend to catch and kill these fish. For a small permit price, two tarpon per licensed angler are allowed to be caught and killed each day. The angler must also report information on where the fish was caught and its size to the Florida Marine Research Institute for further tarpon research. This permit program has greatly reduced the number of tarpon killed over the past few years. In 1989, just before the permit program was instituted, it is estimated that 342 tarpon were caught and killed by anglers. In 1998, the number of tarpon caught and killed by anglers decreased to 70.
Commercial harvesting of M. atlanticus is not permitted.
US Federal List: no special status
CITES: no special status
Megalops atlanticus develops in three distinct stages over a period of months. Two to three days after spawning, the eggs hatch into planktonic leptocephalus larvae. Over a period of two to three months these leptochephalus larvae grow to a length of 6 to 25 mm and float inshore on currents to continue their development. In stage two, tarpon actually stop growing and shrink to a size of approximately 14 mm. This stage lasts anywhere from 20 to 25 days. In stage three, lasting seven to eight weeks, the tarpons continue their growth and at around 40 mm become juveniles.
The sexual maturation of M. atlanticus is based primarily on the length of the fish. In males it occurs between 90 to 117.5 cm and in females at approximately 128.5 cm. This maturation can occur between the ages of 6 to 13 years for both sexes.
Development - Life Cycle: metamorphosis
There have been a few reported cases of ciguatera poisoning from eating tarpon. Ciguatera poisoning causes nausea, vomiting, and diarrhea. Neurological signs of poisoning include headache and temperature sensitivity and cardiovascular signs can include arrhythmia and reduced blood pressure. There have also been reports of injuries and even deaths to sport fishers attempting to catch tarpon. These fish are very large and have lots of thrashing power when hooked on a fishing line. When pulled into a boat they can thrash their bodies around vigorously and injure the angler. It is best to wear out the fish before pulling it on board to avoid any injury.
Negative Impacts: injures humans (carries human disease)
Tarpon mainly benefit humans through recreational activities. In Florida, tarpon are a very important game fish, bringing in millions of dollars annually through charter fishing trips. In some areas, Megalops atlanticus is marketed for its flesh. It is considered a delicacy in South America despite the fact that it is very bony. Large scales of tarpon are used as ornamentation on home decorations and are also used in the manufacturing of artificial pearls.
Positive Impacts: food ; body parts are source of valuable material; ecotourism
Tarpon are prey and are also predators throughout their ecosystem. Large sharks, alligators and porpoises feed on tarpon and in return tarpon feed on smaller fish, crabs and shrimp.
Lecithochirium microstomum, a trematode parasite, is found in the stomachs of tarpon, and Bivescula tarponis, another trematode parasite, occurs throughout the intestines. The isopods Nerocila acuminata and Cymothoa oestrum, and the copepod Paralebion pearsei, are found on the external surfaces of tarpon. Commensal remoras often attach themselves to large tarpon and go along for the ride.
Commensal/Parasitic Species:
The diet of Megalops atlanticus changes throughout development. In the first stage of their development, tarpon get nutrients directly from the water. As juveniles, they feed on zooplankton, small fish, and insects. As adults, tarpon move away from zooplankton and feed only on fish and crustaceans. Some main food sources are Atlantic needlefish (Strongylura marina), pinfish (Lagodon rhomboides), and many species of crabs and shrimp. Megalops atlanticus swallows its prey whole because of the small size of its teeth. Tarpon feed mostly on mid-water prey during the day and night.
Animal Foods: fish; insects; aquatic crustaceans; zooplankton
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)
Megalops atlanticus, commonly known as the Atlantic tarpon, is primarily found in the warm, shallow, coastal regions of the eastern and western Atlantic Ocean. These fish have a wide range along the coastal areas from the United States to Brazil in the western Atlantic and from Senegal to the Congo on the eastern Atlantic coast. They have occasionally been sighted as far north as Nova Scotia and as far south as Argentina in the western Atlantic and along the coasts of Portugal, the Azores and the south of France in the eastern Atlantic. Megalops atlanticus is also found throughout the Caribbean, Gulf of Mexico, around Bermuda and in the eastern Pacific Ocean near Cobia Island in Panama because of movement through the Panama Canal.
Biogeographic Regions: nearctic (Native ); ethiopian (Native ); neotropical (Native ); atlantic ocean (Native ); pacific ocean (Introduced ); mediterranean sea (Native )
Tarpon are found in estuaries, bays, lagoons and have even been known to travel up into freshwater rivers. Megalops atlanticus has the ability to tolerate euryhaline environments and can also tolerate environments which are oxygen poor by gulping air at the surface. The only environmental constraint on their habitat is temperature. They occupy warmer waters in subtropical areas and sudden temperature changes have been known to kill tarpon in large numbers. M. atlanticus is a pelagic fish.
Range depth: 0 to 30 m.
Habitat Regions: temperate ; tropical ; saltwater or marine ; freshwater
Aquatic Biomes: pelagic ; rivers and streams; coastal ; brackish water
Other Habitat Features: riparian ; estuarine
Megalops atlanticus is known to have a very long lifespan. Tarpon are expected to live approximately 55 years in the wild and approximately 60 years in captivity. The oldest recorded age the wild was 55 years for a female and 43 years for a male. In captivity, the oldest recorded was a female tarpon which reached the age of 63 years.
Range lifespan
Status: wild: 55 for female and 43 for male (high) years.
Range lifespan
Status: captivity: 63 for a female (high) years.
Average lifespan
Status: wild: 55 years.
Average lifespan
Status: captivity: 55 years.
Megalops atlanticus is a large fish with a deep blue to black dorsal coloration and silver side and ventral coloration. Tarpon have a forked, homocercal caudal fin. The single dorsal fin is short and made up of 13 to 15 soft rays; the last of these rays is elongated into a heavy filament. The anal fin is a triangle and is made up of 22 to 25 soft rays; the last of these rays is also elongated into a filament but is much smaller than that of the dorsal fin. Tarpon have large pelvic fins on the abdomen and long pectoral fins made up of 13 to 15 soft rays. The scales of tarpon are cycloid and large. There are 37 to 42 of these large scales along the lateral line.
Tarpon vary greatly in size and females are generally larger than males. Megalops atlanticus can grow up to lengths of 240 cm and reach a mass of 161 kg. Females, on average, have a mean fork length of 167.7 cm whereas males have a mean fork length of 144.7 cm.
The lower jaw of M. atlanticus is large and protruding. Tarpon have very small, densely packed teeth placed all over the mouth including the jaws, tongue and skull base. In addition to these fine teeth, tarpon have a bony plate on the upturned portion of the lower jaw which helps them crush some of their prey.
Tarpon have a modified swim bladder which allows them to live in oxygen-poor environments. Alveolar tissue in the swim bladder and a duct connecting the swim bladder to the esophagus allow tarpon to breath atmospheric air. Studies have shown that tarpon are obligate air breathers. Even in oxygen-rich environments tarpon still gulp air from the surface.
Range mass: 161 (high) kg.
Range length: 204.5 (high) cm.
Average length: 156.2 cm.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Zooplankton and small fish feed on M. atlanticus during the larval stage. As tarpon mature, their main predators become bull sharks (Carcharhinus amboinensis), great hammerhead sharks (Sphyrna lewini), American alligators (Alligator mississippiensis) and many species of porpoise.
Tarpon exhibit a color pattern called countershading, which most fish use as a method to prevent predation. Their dorsal surface is generally a dark color. When a predator is looking down on a tarpon from above, the dark color of its dorsal side helps it blend in with the dark, deep waters. The ventral surface of most fish is lighter in color, silver in the case of the tarpon. This countershading helps it blend in with the lighter color of the surface water when a predator is looking at it from below.
Known Predators:
Anti-predator Adaptations: cryptic
Tarpon spawn seasonally and are multiple spawners. These fish have been seen swimming in a circular, rotating fashion. This movement may be a way for tarpon to initiate spawning. Large schools of Megalops atlanticus, 25 to 200 individuals, migrate offshore to spawn. Tarpon are broadcast spawners. Fertilization of the eggs is external.
Mating System: polygynandrous (promiscuous)
Large schools of Megalops atlanticus, 25 to 200 individuals, migrate offshore between May and August to spawn. There is some evidence to suggest that tarpon can spawn year round, but this is not common. There is also evidence to suggest that the lunar phase influences when tarpon spawn. Successful hatchings occur within the week following a new moon. These fish have a very high fecundity rate, with large females producing more than 12 million eggs. Tarpon spawn in the deeper waters and allow the currents to carry their eggs to inshore nurseries to develop. The eggs hatch into leptocephalus larvae after two or three days.
Breeding interval: Megalops atlanticus spawns once annually
Breeding season: Evidence now suggests that tarpon can spawn throughout the year, but most spawn May to August
Range number of offspring: 4.5 million to 20.7 million.
Average number of offspring: 12 million.
Range gestation period: 2 to 3 days.
Range age at sexual or reproductive maturity (female): 6 to 13 years.
Range age at sexual or reproductive maturity (male): 6 to 13 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); broadcast (group) spawning; oviparous
Tarpon expend energy travelling to their breeding grounds and producing their eggs and sperm, but they make no further investment in their offspring.
Parental Investment: no parental involvement
The Atlantic tarpon (Megalops atlanticus) is a ray-finned fish that inhabits coastal waters, estuaries, lagoons, and rivers. It is also known as the silver king. It is found in the Atlantic Ocean, typically in tropical and subtropical regions, though it has been reported as far north as Nova Scotia and the Atlantic coast of southern France, and as far south as Argentina. As with all elopiformes, it spawns at sea. Its diet includes small fish and crustaceans.[5]
The tarpon has a reputation for great aerobatics, attaining astonishing size, and having impressive armored scales. It is generally considered to be of poor food quality, but it is highly valued as a game fish by recreational fishermen.
Atlantic tarpon evolved approximately 18 million years ago and are one of the oldest living fish.[6]
It has been recorded at up to 2.5 m (8 ft 2 in) in length and weighing up to 161 kg (355 lb).[7] Males rarely weigh more than 100 pounds.[6]
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.[6]
The Atlantic tarpon's most significant predators are sharks and humans.[7]
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.[8]
The scales of Atlantic tarpon have been used as nail files and for decorative purposes since pre-history. Their crushed up scales also feature in traditional medicine, particularly in Brazil.[9]
An Atlantic tarpon is depicted in the fresco on the ceiling of the Sistine Chapel completed by Michelangelo around 1510.[10]
The Atlantic tarpon was first described scientifically by zoologist Achille Valenciennes in 1847 as Megalops atlanticus, Megalops being inspired by their large eyes.[6]
The tarpon is the official state saltwater fish of the American state of Alabama.[11][12]
Atlantic tarpon adapt well to urban and suburban environments due to their tolerance for boat traffic and low water quality. Around humans Atlantic tarpon are primarily nocturnal.[13]
While the Atlantic tarpon is rarely consumed in the United States, subsistence and commercial fisheries exist in a number of countries.[7] Both their meat and roe are consumed.[8]
Tarpons are considered one of the great saltwater game fishes, not only because of their size and their accessible haunts, but also because of their fighting spirit when hooked; they are very strong, making spectacular leaps into the air. They are the largest species targeted by fly fishermen in shallow water.[14] The flesh is undesirable, commonly described as being smelly and bony. In Florida and Alabama, a special permit is required to kill and keep a tarpon, so most tarpon fishing there is catch and release. In Texas they are a revered game fish with only potential state records (fish over 75 inches) allowed to be kept.[15]
Tarpon are known by English speaking anglers as “The Silver King."[16]
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.[17] In the Gulf of Mexico there are two distinct populations divided by the Mississippi River Delta.[15]
Atlantic tarpon are highly migratory and often cross international boundaries. This introduces challenges in management and conservation.[7]
Scientific studies indicate schools have routinely migrated through the Panama Canal from the Atlantic to the Pacific and back for over 80 years.[18][17] 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.[19] In the Pacific a population has become established in Costa Rica.[20]
Atlantic tarpon breed in spawning aggregations in the open ocean. Atlantic tarpon share a unique larval stage known as a leptocephalus with bonefish, ladyfish, and eels. Unlike the larvae of other fish these larvae do not eat as their long slender bodies have very low energy requirements. While larvae the Atlantic tarpon's teeth grow pointed forward to keep debris out of their mouth. The leptocephali develop into juveniles which make their way inshore, often into stagnant water with a very low oxygen content which can't be tolerated by most of their predators. When they are about three years old Atlantic tarpon migrate from these backwater habitats to a variety of nearshore ones, growing rapidly but primarily in length as opposed to girth. At around eight years of age an Atlantic tarpon reaches its sexual maturity and begins to gain length as well as girth. Growth rates also diverge at this point with males growing much slower than females. Sexually mature Atlantic tarpon will begin migrating to join spawning aggregations.[6]
The Atlantic tarpon (Megalops atlanticus) is a ray-finned fish that inhabits coastal waters, estuaries, lagoons, and rivers. It is also known as the silver king. It is found in the Atlantic Ocean, typically in tropical and subtropical regions, though it has been reported as far north as Nova Scotia and the Atlantic coast of southern France, and as far south as Argentina. As with all elopiformes, it spawns at sea. Its diet includes small fish and crustaceans.
The tarpon has a reputation for great aerobatics, attaining astonishing size, and having impressive armored scales. It is generally considered to be of poor food quality, but it is highly valued as a game fish by recreational fishermen.
