Atlantic Tarpon

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Copyright © Dawn Witherington

Similar species: Megalops cyprinoides, Indo-Pacific tarpon

Description

Because of their large size, legendary strength and stamina, magnificent beauty, and habit of jumping when hooked, the tarpon is among the world's most prized game fish. Adult tarpon are four to eight feet long and weigh 60 to 280 pounds. They have slender bodies covered with large platelike scales. Their bodies are a silvery and shiny with blue-grey or greenish backs and dark fins and tail. The tail is deeply forked and the last ray of the dorsal fin is elongated and thin. A tarpon's mouth is large and upward directed with very prominent lower jaws that extend forward to form the "snout" of the fish.

Atlantic Tarpon

Tarpon are a very old and interesting fish. Fossil records date back to 100 million years ago. They are related to ladyfish, bonefish, and eels.

Another unusual aspect of the tarpon is the ability to gulp air at the surface and to breathe through their swim bladder. In most fishes, the swim bladder serves only as a buoyancy device, however, in the tarpon it has developed a respiratory function that supplements the gills. This allows the juvenile fish to survive in low-oxygen waters where fewer predators are found. Tarpon frequently rise to the surface and take gulps of air, which gives them a short burst of energy. This accounts for the characteristic rolling behavior of tarpon at the surface.

Occurrence

The Atlantic tarpon is found throughout the Gulf of Mexico, on the coast of the western Atlantic Ocean from Brazil to Virginia, and on the west coast of Africa. Their range has extended to the west cost of Panama and Costa Rica, presumably via the Panama Canal. They are occasionally found in Canadian Atlantic waters. The similar Indo-Pacific tarpon, Megalops cyprinoides, is found on the east coast of Africa and throughout Asia, Australia, and the western Pacific Ocean.

Tarpon are highly migratory. Satellite tag studies have shown that fish from Texas and and elsewhere in the Gulf commonly range as far as the Caribbean Sea and the east cost of the U.S. as far north as Virginia. Tarpon that winter in Florida and Mexico regularly move along the northern Gulf of Mexico coastline, including Mississippi waters, during summer.

Tarpon are a pelagic species that lives near the surface. They are commonly found to depths of about 100 feet, though recent research with satellite tags has shown that they may dive to depths greater than 400 feet.

Tarpon tolerate wide ranges in salinity, from the open ocean to brackish bays and even freshwater rivers. Tarpon also have an unusual ability to survive in water with very low dissolved oxygen levels that would kill most fishes. Water temperature is the most significant limitation to the tarpon's range. They prefer a water temperature of 72 to 82°F (22 to 28°C). Below 60°F (15.6°C) they become inactive, and temperatures below 40°F (4.5°C) can be lethal for adults, while juvenile tarpon have been shown to be killed by 50°F water.

Very little is known about their presence on the Mississippi coast, though it is well documented that adult tarpon were common before the coast was developed in the early 20th century.  Recent findings of larval and juvenile tarpon in the Mississippi Sound by researchers at the GCRL are aiding in our understanding of the role of our waters to this unique fish.

Life Cycle & Reproduction

Tarpon have an unusual and complex life cycle, particularly at the earliest stages. Their habitat, like their diet, changes as they mature.

Spawning/Eggs - Tarpon spawn offshore in warm, isolated areas, usually in late spring to late summer and probably in association with a full moon or new moon. Tarpon are broadcast spawners, meaning the fish release sperm and egg into the water to be fertilized and provide no parental care for the young. Females can release up to 12 million eggs at once and produce between four million and 20 million eggs per breeding season. Fertilized eggs drift on open water until hatching. Tarpon eggs lack the large yolk sac found in the eggs of most fish species.

Leptocephalus - Tarpon eggs soon hatch after fertilzation into a nearly transparent leptocephalus stage that resembles a piece of clear ribbon. Tarpon, bonefish, ladyfish, and true eels are the only fishes that have a leptocephalus life stage. It is beneficial because the transparent body and lack of a yolk sac make it very difficult for predators to see it. Lacking a yolk sac for nourishment, the leptocephalus larvae absorbs nutrients from the water through their skin. Somehow, the delicate tarpon larvae manage to move up to 100 miles from offshore spawning areas to the estuaries where they will spend 20 to 60 days before transforming into the next larval stage.

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Composite photo of a tarpon leptocephalus collected in a marsh on the Mississippi coast by Pat Graham and Jim Franks


As the leptocephalus matures it actually shrinks before growing again. In a sluggish growth phase that may last as long as several months, the leptocephalus metabolizes its own tissues as it metamorphoses into its juvenile form.

It is generally thought that tarpon at the leptocephalus stage remain in clear, warm oceanic waters. However, tarpon leptocephali have recently been found by GCRL researchers along shorelines adjacent to Mississippi salt marshes.

Juvenile tarpon number MA0067 - captured with a cast net, tagged, and released near Ocean Springs, Mississippi by Jim Franks and Paul Grammer.
Juvenile tarpon number MA0067 - captured with a cast net, tagged, and released near Ocean Springs, Mississippi by Jim Franks and Paul Grammer.
Click for larger image.

Juvenile - Tarpon remain in the juvenile stage until six months to two years of age. Juveniles are typically found in estuaries, salt marshes, creeks, and rivers, in shallow water with a sandy mud bottom. Juveniles grow rapidly from about 1.5 to 24 inches.

Sub-Adult and Adult - Sub-adult tarpon remain in either inshore waters or move offshore. At seven to thirteen years of age and a length of about 30 to 49 inches, tarpon become sexually mature and their growth rate slows. Adults move freely between freshwater rivers, brackish estuaries and coastal waters, and the open ocean. Tarpon may live as long as 55 years.

Diet and Predators

The diet of immature tarpon changes as the fish matures. Leptocephalus tarpon absorb nutrients from the water directly through their skin. Smaller juveniles feed primarily on zooplankton, and also catch mosquito larvae and other insects, small fish, and grass shrimp. Beginning at a length of about five inches, the diet gradually shifts to fish.

Adult tarpon feed primarily on fishes, shrimp, and crabs. Fish commonly eaten include sardines, anchovies, mullet, catfish, pinfish, and silversides. Their food is swallowed whole. Tarpon feed during both day and night.

Juvenile tarpon are preyed upon by a variety of fishes and by wading birds. As adults, tarpon are preyed upon only by sharks and humans. While tarpon are not considered a food fish in the U.S., their meat and roe are consumed in other countries.

Biological Research

GCRL

The life history of tarpon in Mississippi waters is a grand mystery. We know that adult tarpon are found near the barrier islands and offshore and that large juvenile tarpon (five pounds or larger) are found year-round in Back Bay near the mouth of the Biloxi River. GCRL's Tarpon Research Team has been investigating the missing pieces of the puzzle. Their groundbreaking work is the first attempts at unraveling the mysteries of tarpon on the northern Gulf Coast. Members of the team include Senior Fisheries Scientist Jim Franks, John Anderson, Dr. Steve Curran, T.J. Fayton, Dyan Gibson, Pat Graham, Paul Grammar, Jeremy Higgs, and Jason Tilley. The tarpon team is also working collaboratively with Dr. Will Stein, University of New Orleans, in biological studies of tarpon off Louisiana and Mississippi.

The work has been supported through a Mississippi Tidelands Trust Fund Program Grant from the Mississippi Department of Marine Resources. HOSSFLY, the Historic Ocean Springs Flyfishing Club, has supported GCRL tarpon research with a grant and field volunteer work by members Tom Herrington, Mike Arguelles, and Don Abrams.

The work began in 2006 when Jim Franks first found juvenile tarpon in Mississippi. A local resident reported catching two in a bait trap and the tip led Jim to a muddy ditch that turned out to be a haven for young tarpon. During succeeding years, team members made regular sampling trips with cast nets. It's been revealed that very young tarpon are relatively common are in coastal marshes along the Mississippi coast and that tarpon are overwintering in Mississippi waters. Getting dirty in the bayous and ditches of coastal Mississippi has yielded several hundred juveniles of all sizes. The team is working with local anglers and monitoring fishing rodeos to collect reports of larger fish from the Gulf and coastal rivers.

Jim Franks with a juvenile tarpon to be tagged and released back into the marsh creek in the background.
Jim Franks with a juvenile tarpon to be tagged and released back into the marsh creek in the background.

The effort made a big step forward in 2007, when 50 juvenile tarpon were captured and raised in tanks at GCRL for nine months. Half of the fish were tagged and released and half were released without tags.

The GCRL team continues to tag and release juvenile tarpon five to six inches in length and larger. Tagged fish have been captured again after several weeks at large, having remained in the same location.

For the past three years, John Anderson and Pat Graham have regularly waded though boggy marshes pulling a fine-mesh net behind. Their work has turned up tiny tarpon in the leptocephalus stage hidden among the grasses, mud, detritus, and shrimp the net collects. During summer 2013 Pat collected an unprecedented 42 leptocephali along the Jackson County shoreline.

Sudden weather changes have also produced collecting opportunities. Recently, a visit to a known tarpon hangout on the morning after a November 2013 cold front passed through turned up 31 juvenile tarpon that had succumbed to low water temperature.

Specimens are also being collected for DNA analysis and other investigations. The team has removed the tiny otolith bones from leptocephalus tarpon and are establishing the age of the fish by examining daily growth rings. Working with an oceanographer who will study the recent history of weather and current observations, they hope to back-track and determine where the fish were spawned.

Tarpon Genetic Recapture Study - Opportunity for Angler Participation

The Florida Fish and Wildlife Conservation Commission (FWCC), in partnership with Mote Marine Laboratory, is conducting a tarpon tracking program using DNA samples submitted by anglers. A simple kit, provided free of charge, includes a small sponge, vials, and data slips. The angler obtains a DNA sample by scraping the sponge on the tarpon's jaw and delivers or mails the sample to FWCC. The DNA information goes into a database for comparison to other samples, making it possible for us to understand the movements and growth of these fish when they are caught and sampled again.

The kits are small and samples require no refrigeration or special handling. Any angler who anticipates catching a tarpon is encouraged to obtain a kit and participate in the Tarpon Genetic Recapture Study.

Satellite Tracking of Tarpon

The Tarpon and Bonefish Research Center (TBRC) at the University of Miami, in collaboration with the Bonefish Tarpon Trust, have been tracking tarpon movements in the southeastern U.S. and the Gulf of Mexico using “pop-up” archival transmitting tags since 2001. The tags are attached to tarpon and programmed to release after a period of time, when they float to the surface and transmit data on depth, water temperature, salinity, light levels, and position to a satellite.

The video below shows the movements of a tarpon tagged on the Alabama Coast in 2007. (Source: Project Tarpon)

Mote Marine Laboratory Tarpon Conservation Initiative

The Mote Marine Laboratory Tarpon Conservation Initiative is a large-scale acoustic tagging project to determine the movements of adult tarpon in and around Boca Grande and Charlotte Harbor and monitor these patterns change over time and in response to different stressors. 50 adult tarpon will be tagged annually for five years and individually monitored with an array of 100 receivers.

Tarpon as a Sport Fish

Silver King: The Birth of Big Game Fishing, an excellent 56-minute video from WGCU Public Media. View online on YouTube or WGCU website.
Silver King: The Birth of Big Game Fishing, an excellent 56-minute video from WGCU Public Media. View online on YouTube or WGCU website.

Big game fishing is said to have begun on March 19, 1885 when William Halsey Wood documented his catch of the first large tarpon on rod and reel near Sanibel Island, Florida. He caught the 93-pound tarpon on a five-foot bamboo rod using a mullet for bait. Soon after Thomas Edison became a devoted tarpon angler, though he never succeeded in equaling Wood's catch.

Today, the tarpon sport fishery and numerous tarpon tournaments throughout the fish's range are a valuable component of many local coastal economies. It is estimated that tarpon fishing in the U.S. creates more than $6 billion of revenue annually.

The tarpon fishery is not regulated in Mississippi or Louisiana. Other Gulf states impose size and catch restrictions.

Good Practices for Tarpon Angling

More detailed suggested handling methods for releasing tarpon are outlined here.

Estimating Weight of Tarpon

The graph provides a means to estimate the weight of a tarpon without killing and weighing the fish, using measurements of fork length and dorsal girth. Click the image to open a larger version. An online calculator is available here.

The graph provides a means to estimate the weight of a tarpon without killing and weighing the fish, using measurements of fork length and dorsal girth.

Conservation Status

Excerpted from IUCN Red List of Threatened Species.

The major threats to this species are the consumptive fishery, habitat degradation and loss (especially to sexually immature individuals (0 to 9 years) and bycatch mortality. The substantial loss of habitat, large directed recreational fisheries throughout its range, and evidence of regional declines raise concerns regarding long-term population stability. There has been no formal stock assessment of tarpon in any portion of the species' range; however, multiple lines of evidence suggest that populations of Atlantic tarpon appear to have declined from historic levels throughout their range. This species is currently listed as Vulnerable under A2bd.  Additional information about the direction and magnitude of regional population trends will warrant future attention.

Tarpon on the Mississippi Coast

19th and Early 20th Centuries

Tarpon were once commonly caught on the Mississippi coast from boats and even from piers on the mainland. These images document two catches. The fish in the first photo was described in newspaper accounts as the first tarpon caught on rod and reel in Mississippi. Just ten years earlier, the first documented catch of a large tarpon on rod and reel had been made in southwest Florida.

Captain Ernest Desporte and what was reported to be the first tarpon caught in Mississippi on rod and reel, on August 28, 1895. The fish was described as a "5'8-1/2" Silver King." Captain Desporte was serving as the harbor master at Ship Island and caught the fish in the Mississippi Sound
Captain Ernest Desporte and what was reported to be the first tarpon caught in Mississippi on rod and reel, on August 28, 1895. The fish was described as a "5'8-1/2" Silver King." Captain Desporte was serving as the harbor master at Ship Island and caught the fish in the Mississippi Sound
"Here's one that Didn't Get Away" from Way Down South magazine, December 5, 1925
"Here's one that Didn't Get Away" from Way Down South magazine, December 5, 1925

Today

A young tarpon collected on the Tchoutacabouffa River after a cold front in 2012. The fish was spotted by # (right) and collected by GCRL scientist Steve Curran (left) with the assistance of volunteer Mike Arguelles.
A young tarpon collected on the Tchoutacabouffa River after a cold front in December 2010. The fish was spotted by Louie Pinto (right) and collected collected at Parker’s Creek near the Tchoutacabouffa River by GCRL scientist Steve Curran (left) with the assistance of volunteer Mike Arguelles.
GCRL technician displays a juvenile tarpon caught near the Gulf Coast Research Laboratory by cast net. The fish was tagged and released.
GCRL biologist Paul Grammer displays a juvenile tarpon caught near the Gulf Coast Research Laboratory by cast net. The fish was tagged and released.

Resources and References

 


Tarpon Photos and Videos

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The Silver King (Atlantic Tarpon) - The Beauty Beneath the Docks

This video offers an interesting underwater perspective of tarpon alongside and beneath a dock.