(DRAFT) - Taxonomy
Species tarpon
Species Id M010406
Date 26 AUG 96
TAXONOMY
NAME - tarpon
OTHER COMMON NAMES - big scale, caffum, grande ecaille, grande ecoy, jewfish, sabalo, sabilo real, sadina, savalle, savallo, savaloreal, savanilla, silver fish, silver king, tarpom and tarpum
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - Chordata,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Elopiformes,
FAMILY AND SUBFAMILY - Elopidae or Megalopidae,
GENUS AND SUBGENUS - Megalops,
SPECIES AND SSP - atlanticus,
SCIENTIFIC NAME - Megalops atlanticus
AUTHORITY - Valenciennes
TAXONOMY REFERENCES - 223
COMMENTS ON TAXONOMY -
The tarpon was placed in the Elopidae by Gosline (1971) and Robins et al.
(1980), whereas Greenwood et al. (1966), Forey (1973a, 1973b), and Nelson
(1984) recognized the Megalopidae and Elopidae as separate families within
the suborder Elopoidei. The issue is equivocal and unlikely to be resolved
soon.*223*
Taxonomy - 1 (DRAFT) - Status
Species tarpon
Species Id M010406
Date 26 AUG 96
STATUS
Coded Status
Sport Fish
REFERENCES FOR STATUS - 223
COMMENTS ON STATUS -
The tarpon is the premier inshore big-game fish of the Florida coast.
Esteemed for its stamina, strength, and especially its leaping prowess, it
is avidly sought by anglers. Numerous annual tournaments are directed
specifically at this species. Tourist revenues generated by the fishery are
formidable. Tarpon are considered inedible in the United States because of
the boniness of the flesh, and therefore do not suport commercial
fisheries.*223*
The tarpon fisheries are solely recreational; no commercial fishery exists
for this species in the United States.*223*
Status - 1 (DRAFT) - Distribution
Species tarpon
Species Id M010406
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine FL2
Marine FL2
Marine FL3
Estuarine FL2
Estuarine FL3
Estuarine SB2
Estuarine SB3
Riverine FL2
Riverine FL3
Riverine SB2
Riverine SB3
REFERENCES FOR NWI - 223
COMMENTS ON HABITAT ASSOCIATIONS -
Habitats of Stage I tarpon larvae are clear, warm, oceanic waters within
100 m of the surface.*223*
Stage II and III tarpon larvae and juveniles live in salt marsh and
mangrove ponds, tidal creeks, rivers, ditches, beaches, and
mosquito-control impoundments. These habitats are typically shallow (<1m),
have a sandy mud or mud substrate with no rooted submerged vegetation, are
lined by reeds or mangroves, usually have turbid or dark-stained waters,
and may be either stagnant or have considerable current.*223*
In eastern Florida marshes, Stage III larvae have been found in ditches at
the headwaters of small creeks. Small juveniles (40-80 mm SL) lived in
larger ditches and creeks, especially in the deeper pools. Large juveniles
were found in larger canals and rivers. Juvenile tarpon eventually
emigrate from marsh and mangrove habitats and enter coastal waters when
they reach about 600-800 mm TL.*223*
Habitat Associations - 1 (DRAFT) - Food Habits
Species tarpon
Species Id M010406
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
OTHER
REFERENCES FOR TROPHIC LEVEL - 223
LIFESTAGE FOOD FOOD PART
Larva Zooplankton Not Applicable
Larva Copepods Not Specified
Larva Insects Not Specified
Larva Fish Not Specified
Juvenile Crustaceans Not Specified
Juvenile Zooplankton Not Applicable
Juvenile Copepods Not Specified
Juvenile Insects Not Specified
Juvenile Fish Not Specified
Juvenile See Comments; Food
Adult Siluriformes Not Specified
Adult Fish Not Specified
Adult Crustaceans Not Specified
Adult See Comments; Food
REFERENCES FOR ADULT FOOD - 223
REFERENCES FOR JUVENILE FOOD - 223
REFERENCES FOR LARVAE FOOD - 223
COMMENTS ON FOOD -
Stage I tarpon larvae do not forage; nutrients are obtained directly from
seawater by integumentary absorption.*223*
Stage II and III tarpon larvae and small juveniles (<125 mm SL) feed
primarily on zooplankton (e.g., copepods and ostracods) and secondarily on
insects and small fishes; larger juveniles continue to feed on zooplankton,
but progressively increase consumption of insects, fishes (especially
poeciliids and cyprinodontids), crabs, and grass shrimps of the genus
Palaemonetes. Juvenile tarpon are typically crepuscular and nocturnal
foragers.*223*
Adult tarpon are strictly carnivorous and feed primarily on mid-water
prey. Food is swallowed whole.*223*
Adult tarpon feed both nocturnally and diurnally on a variety of organisms
including mullets, pinfish, ariid catfishes, Atlantic needlefish, sardines,
shrimp, and crabs.*223*
COMMENTS ON ADULT FOOD -
Adult tarpon are strictly carnivorous and feed primarily on mid-water
prey. Food is swallowed whole.*223*
Food Habits - 1 (DRAFT) - Food Habits
Species tarpon
Species Id M010406
Date 26 AUG 96
Adult tarpon feed both nocturnally and diurnally on a variety of organisms
including mullets, pinfish, ariid catfishes, Atlantic needlefish, sardines,
shrimp, and crabs.*223*
COMMENTS ON JUVENILE FOOD -
Larger juveniles continue to feed on zooplankton,
but progressively increase consumption of insects, fishes (especially
poeciliids and cyprinodontids), crabs, and grass shrimps of the genus
Palaemonetes. Juvenile tarpon are typically crepuscular and nocturnal
foragers.*223*
COMMENTS ON LARVAE FOOD -
Stage I tarpon larvae do not forage; nutrients are obtained directly from
seawater by integumentary absorption.*223*
Stage II and III tarpon larvae and small juveniles (<125 mm SL) feed
primarily on zooplankton (e.g., copepods and ostracods) and secondarily on
insects and small fishes.*223*
Food Habits - 2 (DRAFT) - Environment Associations
Species tarpon
Species Id M010406
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
L Water Temperature: Specified in Comments
J Water Temperature: Specified in Comments
L
J
A Dissolved Oxygen: Specified in Comments
L Turbidity: Clear water
A Turbidity: Murky water [High turbidity]
J Turbidity: Murky water [High turbidity]
J Water pH: Between 6.5-8.5
G Bottom Type [Aquatic]: Mud or silt
G Bottom Type [Aquatic]: Sand
J Density of Aquatic Vegetation: Low
L Density of Aquatic Vegetation: Low
J Water Depth Preference: 1-5 ft.
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 223
REFERENCES FOR ADULT ENVIRONMENTAL ASSOC_ - 223
REFERENCES FOR JUVENILE ENVIRONMENTAL ASSOC_ - 223
REFERENCES FOR LARVAE ENVIRONMENTAL ASSOC_ - 223
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Tarpon are distinctly thermophilic fish. They have been reported in
cold-related fish kills in Florida. At Port Aransas, Texas, annual tarpon
abundances are correlated with yearly water temperature regimes.*223*
Early Stage I Tarpon larvae occur only in warm ocenaic waters (22.2-30.0
degrees C), and it appears probably that such temperatures are necessary
for proper development of eggs and early larvae.*223*
Studies state that the lower lethal temperature of tarpon is about 10
degrees C.*223*
Throughout most of its life stages, tarpon tolerate a wide range of
salinities. However, early Stage I larvae have been collected only at
oceanic salinities of 28.5-39.0 ppt, and it is likely that such
concentrations are required by eggs, yolk-sac larvae, and early Stage I
Environment Associations - 1 (DRAFT) - Environment Associations
Species tarpon
Species Id M010406
Date 26 AUG 96
larvae of tarpon for proper development.*223*
Beyond Stage I, tarpon are decidedly euryhaline.223
Tarpon are obligate air breathers (the swimbladder contains alveolar
tissue) and are frequently seen "rolling" at the surface gulping air; when
prevented from reaching the surface, they die within 7 to 128 h, even in
highly oxygenated water. Air breathing is imitatively mediated by visual
cues; juveniles in a school come to the surface in rapid succession,
perhaps to reduce individual susceptibilities to predation by fish-eating
birds. The frequency of air breathing is inversely correlated with
dissolved oxygen concentration. Air-breathing precludes mortality in
anoxic waters and allows tarpon to survive under conditions deleterious to
most fishes. Tarpon have this ability at least as early as the beginning
of Stage III.*223*
Aerial spraying and ground fogging for nuisance insect control are widely
practiced in Florida's coastal zone, and agricultural pesticides and
herbicides used in south Florida enter coastal waters. Tarpon are
extremely susceptible to contaminants. Application of dieldrin pellets in
a Florida salt marsh for the control of larval sandflies (Culicoides)
resulted in mortality of Tarpon.*223*
Stage I larvae of tarpon occur only in clear offshore waters. Subsequent
life history stages apppear to be tolerant of high turbidities. Habitats
occupied, especially by juveniles, are generally described as turbid and
dark-stained.*223*
COMMENTS ON ADULT ENVIRONMENTAL ASSOC_ -
Tarpon are distinctly thermophilic fish. They have been reported in
cold-related fish kills in Florida. At Port Aransas, Texas, annual tarpon
abundances are correlated with yearly water temperature regimes.*223*
Studies state that the lower lethal temperature of tarpon is about 10
degrees C.*223*
Beyond Stage I, tarpon are decidedly euryhaline.223
Tarpon are obligate air breathers (the swimbladder contains alveolar
tissue) and are frequently seen "rolling" at the surface gulping air; when
prevented from reaching the surface, they die within 7 to 128 h, even in
highly oxygenated water. Air breathing is imitatively mediated by visual
cues; juveniles in a school come to the surface in rapid succession,
perhaps to reduce individual susceptibilities to predation by fish-eating
birds. The frequency of air breathing is inversely correlated with
dissolved oxygen concentration. Air-breathing precludes mortality in
anoxic waters and allows tarpon to survive under conditions deleterious to
most fishes. Tarpon have this ability at least as early as the beginning
of Stage III.*223*
Aerial spraying and ground fogging for nuisance insect control are widely
practiced in Florida's coastal zone, and agricultural pesticides and
herbicides used in south Florida enter coastal waters. Tarpon are
Environment Associations - 2 (DRAFT) - Environment Associations
Species tarpon
Species Id M010406
Date 26 AUG 96
extremely susceptible to contaminants. Application of dieldrin pellets in
a Florida salt marsh for the control of larval sandflies (Culicoides)
resulted in mortality of Tarpon.*223*
Adult tarpon apppear to be tolerant of high turbidities. Habitats
occupied are generally described as turbid and dark-stained.*223*
COMMENTS ON JUVENILE ENVIRONMENTAL ASSOC_ -
Tarpon are obligate air breathers (the swimbladder contains alveolar
tissue) and are frequently seen "rolling" at the surface gulping air; when
prevented from reaching the surface, they die within 7 to 128 h, even in
highly oxygenated water. Air breathing is imitatively mediated by visual
cues; juveniles in a school come to the surface in rapid succession,
perhaps to reduce individual susceptibilities to predation by fish-eating
birds. The frequency of air breathing is inversely correlated with
dissolved oxygen concentration. Air-breathing precludes mortality in
anoxic waters and allows tarpon to survive under conditions deleterious to
most fishes. Tarpon have this ability at least as early as the beginning
of Stage III.*223*
Juvenile tarpon apppear to be tolerant of high turbidities. Habitats
occupied are generally described as turbid and dark-stained.*223*
COMMENTS ON LARVAE ENVIRONMENTAL ASSOC_ -
Early Stage I Tarpon larvae occur only in warm oceanic waters (22.2-30.0
degrees C), and it appears probably that such temperatures are necessary
for proper development of eggs and early larvae.*223*
Throughout most of its life stages, tarpon tolerate a wide range of
salinities. However, early Stage I larvae have been collected only at
oceanic salinities of 28.5-39.0 ppt, and it is likely that such
concentrations are required by eggs, yolk-sac larvae, and early Stage I
larvae of tarpon for proper development.*223*
Stage I larvae of tarpon occur only in clear offshore waters.*223*
Environment Associations - 3 (DRAFT) - Life History
Species tarpon
Species Id M010406
Date 26 AUG 96
LIFE HISTORY
MORPHOLOGY: The tarpon is herring-like in general appearance but is
readily distinguished from clupeids by the presence of an elongate bony
angular plate between the branches of the lower jaw and a much larger mouth;
the jaw extends considerably posterior to the rear edge of the orbit. The
belly is not keeled or serrated as in herrings, but is relatively broad
and covered with ordinary scales.*223*
The following description of the Elopidae is summarized form Jordan and
Evermann (1969). Body elongate, somewhat compressed, and covered with
silvery cycloid scales. No scales on head. Lateral line present. Mouth
broad, lower jaw prominent. Premaxillaries short and nonprotactile;
maxillaries form lateral margins of the upper jaw. Eye relatively large,
with adipose eyelid. Bands of villiform teeth on jaws, vomer, palatines,
pterygoids, tongue, and base of skull. Opercular bones thin, with expanded
membranous margins. Gill membranes entirely separate and free from the
isthmus; gillrakers long and slender. Dorsal fin inserted over or slightly
behind the pelvics. Caudal fin forked, dorsal and anal fins depressible
into scaly sheaths. No spines or adipose fin. Very long accessory scales
at the pectorals and pelvics.*223*
Body oblong, compressed, and covered with large, thick, silvery, cycloid
scales. Mouth large and superior. Branchiostegal rays 23. Dorsal fin with
12 rays, inserted considerably behind the pelvics. Anal deeply falcate, 20
rays, about twice as long as dorsal, has greatly elongated last ray. Caudal
widely forked and scaly. Lateral line nearly straight, 41 to 48 scales; its
tubes radiate widely over the surface of the scales. Vertebral counts 53 to
57. Color bright silver, with dorsal surface somewhat darker than ventral.
Reaches 2 to 2.6 m and over 90 kg.*223*
REPRODUCTION: Tarpon are believed to spawn throughout most of their range
in offshore waters. Researchers have inferred from larval capture locations
that spawning took place in the Florida Straits, Gulf Stream, and Caribbean.
Other studies have provided strong evidence (based on the collection of
very young larvae) that tarpon spawn off the Caribbean coast of Mexico near
Cozumel and Banco Chinchorro (Yucatan Channel), off west-central Florida,
and off the southern part of Veracruz, Mexico. The presence of small
larvae off Georgia and North Carolina indicates that spawning occurs there
also, and probably to some extent along the entire coast from Florida to
Cape Hatteras.*223*
Fecundity of a tarpon 2 m long was estimated to be about 12,200,000. Sexual
maturity is attained at a total length (TL) of about 120 cm.*223*
Studies have described and illustrated late yolk-sac larvae of tarpon. His
smallest specimen, 5.7 mm in notochord length (NL), retained only trace
amounts of yolk, indicating that the yolk-sac stage ends at about 6 mm
NL.*223*
Summarizing various references on the occurrences of larval tarpon, studies
noted that Stage I larvae occur from mid-May to late August,and Stage II
larvae from late June to early October: they inferred that spawning occurs
Life History - 1 (DRAFT) - Life History
Species tarpon
Species Id M010406
Date 26 AUG 96
in late spring or early summer.*223*
BEHAVIOR: Stage I tarpon larvae do not forage; nutrients are obtained
directly from seawater by integumentary absorption.*223*
Adult tarpon are strictly carnivorous and feed primarily on mid-water
prey. Food is swallowed whole.*223*
LIMITING FACTORS: Predation by carnivorous zooplankters and small fishes
undoubtedly causes high mortality of eggs and larvae of tarpon before the
larvae enter coastal nursery marshes. Tarpon are probably preyed upon by
piscivorous birds, and adult tarpon are occasionally eaten by sharks,
porpoises, and alligators.*223*
The digenetic trematode Lecithochirium microstomum occurs in the stomach of
tarpon. The isopods Nerocila acuminata and Cymothoa oestrum are external
parasites. Studies reported the copepod Paralebion pearsei from tarpon.
The trematode Bivescula tarponis is present in the pyloric caecae and along
the entire length of the intestine. Though not parasitic, remoras (Remora
remora) are commonly observed attached to large tarpon.*223*
POPULATION ATTRIBUTES:
GROWTH Post yolk-sac larval development in tarpon progresses through three
distinct stages. Stage I is an initial period of length increase that
culminates in the development of a fully formed leptocephalus larva. The
leptocephalus is characterized by a long, ribboon-like, colorless,
transparent body; large fang-like teeth; a very small head; and small fins.
It lacks gills and red blood cells, and its gut is not open. Oxygen and
nutrients are absorbed through the skin. In Stage II, the larva decreases
markedly in length and gradually loses the ribbon-like leptocephalic
morphology. Stage III is a second period of length increase that terminates
with the beginning of the juvenile stage. Late in Stage II and throughout
Stage III the larva undergoes pronounced changes in body form, including
increases in body depth, snout length, head length, dorsal and anal fin
height, and pectoral fin size. Late in Stage III, the body starts to become
opaque and silvery. Juveniles resemble adults in general appearance.*223*
Sizes of Stage I tarpon range from 6 mm NL to 28 mm SL. Duration of Stage I
is estimated to be 2 to 3 months in the ocean. Larval tarpon shrink to
about 14 mm SL during Stage II and become juveniles at about 40 mm SL after
Stage III. Duration of Stage II was 20-25 days in the laboratory. Stage
III is estimated to be about 7-8 weeks.*223*
Researchers who examined length-frequency distributions of juvenile tarpon
from a south Florida mangrove pond, reported that modal lengths increased
from 75-80 mm FL in early September to 110-115 mm FL at the end of the
month, and inferred a length increase of about 1.4 mm/day; rates declined by
about 50% in October. Five marked juvenile tarpon (301-376 mm FL when
tagged) in a south Florida drainage ditch grew an average of 1.0 mm/day
(range, 0.7-1.4 mm/day) from 22 August to 20 October. Over the same period,
modal lengths of tarpon in this population increased by 1.4 mm/day. In a
Georgia salt marsh, juvenile tarpon grew at a rate of about 30
mm/month.*223*
Life History - 2 (DRAFT) - Life History
Species tarpon
Species Id M010406
Date 26 AUG 96
Although scales of adult tarpon have distinct rings resembling annuli, these
marks have not been validated as annuli and should be considered with
extreme caution.*223*
On the basis of a graph presented by Moffett and Randall (1957), the
following relation between total length (TL) and fork length (FL) can be
derived for tarpon:
TL = 1.10 FL.
Harrington (1958) developed the following conversions between fork length
(FL), total length (TL), and standard length (SL) in millimeters for tarpon
25-54 mm SL:
FL = 1.1282SL - 1;
TL = 1.3333SL - 2. *223*
LIFE HISTORY CODES -
Breeding/Spawning Season: May
Breeding/Spawning Season: June
Breeding/Spawning Season: July
Display Site: Water
Average Number of Offspring/Reproductive Effort: Grea
REFERENCES FOR LIFE HISTORY- 223
Life History - 3 (DRAFT) - Management Practices
Species tarpon
Species Id M010406
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Adverse Shoreline modification/development
Adverse
Adverse Constructing/maintaining bulkheads, seawalls, and dikes
Adverse Locating/constructing powerlines and other rights-of-way
Existing Other management practices [specified in comments]
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 223
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 223
COMMENTS ON MANAGEMENT PRACTICES -
Offshore and coastal habitats of very young adult tarpon are relatively
immune to human-induced degradation. Conversely, the estuaries, salt
marshes, and coastal mangroves used as nurseries by larval and juvenile
tarpon in Florida are highly vulnerable to changes induced by development.
Factors resulting in the destruction of nursery wetlands include
filling of wetlands, canalization, bulkheading, construction of water-line
right-of-ways and steep-sided boat-access finger-canals, and impoundment of
wetlands for mosquito control. Progress has recently been made in
ameliorating the effects of impoundment for mosquito control because
impoundment does not necessarily result in the destruction of wetlands.
Rather, impounded wetlands, if properly managed, can retain the beneficial
characteristics of natural wetlands while providing adequate mosquito
control. However, access to these wetlands (and subsequent opportunities
for egress) by larval and juvenile tarpon is precluded or severely
curtailed by reduced or non-existent exchange with estuarine waters.
Improved impoundment management strategies, aimed at enhancing exchange
rates, have been proposed.*223*
Management Practices - 1 (DRAFT) - References
Species tarpon
Species Id M010406
Date 26 AUG 96
References
223 * Zale, A.V. 1989. Species Profiles: Life Histories and
Environmental Requirements of Coastal Fishes and Invertebrates
(South Florida) - Ladyfish and Tarpon. 82(11.104) (ed.).
National Wetlands Research Center Washington, DC:17.
References - 1