| Usual fin ray counts are
as follows: 1st dorsal = 5 strong spines, 2nd dorsal = 1 spine
and 9 soft rays, anal = 2 spines and 7-9 rays, pectoral = 1
spine and 5 soft rays (Russell 2002). Young S. barracuda
are characterized by a longitudinal dark stripe down the side
which breaks into black bars over time, remaining visible in
some adults. Overall adult coloration is gray to silver with
a green to blue cast above and white below. The caudal fin is
black with white tips and anterior lobes near the fork. Although
coloration and pattern change, Wilson et al. (2006) found that
S. barracuda retain natural markings over prolonged
periods of time, which can aid in distinguishing individuals
in a population.
Potentially Misidentified Species:
Approximately 26 species of Sphyraena
can be found in tropical and warm temperate waters worldwide.
The range of S. barracuda overlaps with that of the
guaguanche, S. guachancho, the northern sennet, S.
borealis, and the southern sennet, S. picudilla
(Russell 2002 & Robins et al 1986). However, it should be
noted that S. borealis and S. picudilla may
be synonymous. As adults, S. barracuda is the largest
of these species and can be further distinguished by dark splotches
or bars usually visible on the upper side and the number of
scales along the lateral line. Adults also have characteristic
lobes on the anterior margin of the caudal fin (Russell 2002)
and lack the fleshy appendage located on the lower jaw of other
species in the region (Robins et al. 1986).
II. HABITAT AND DISTRIBUTION
Regional Occurrence:
The range of S. barracuda is nearly
circumtropical, encompassing the warm waters of most oceans.
The species is rarely found in northern areas where winter temperatures
dip below 20 °C for extended periods of time. However, some
individuals have been found in the cooler waters off the coast
of the northeast United States, South Africa and Japan (de Sylva
1963). On the east coasts of North, Central and South America,
the range of the great barracuda extends from Massachusetts
to southern Brazil (Robins et al 1986).
IRL Distribution:
Barracuda, especially juveniles, are found
throughout the lagoon in mangrove and seagrass habitats (Fah
1976) where food and shelter are prominent. However, the distribution
of the species in the IRL may be linked in part to temperature.
A study conducted by Kupschus & Tremain (2001) showed that
the majority of fish collected were alongside other tropical
and subtropical species at the southern end of the lagoon.
III. LIFE HISTORY AND
POPULATION BIOLOGY
Age, Size, Lifespan:
Adult S. barracuda commonly reach
2m, with a maximum reported length of 2.3m (Russell 2002). The
maximum age of barracuda is unknown, but the typical lifespan
may often exceed 14 years (de Sylva 1963).
Abundance:
While the great barracuda is generally
a solitary species, juveniles and young adults are commonly
found in seagrass beds and alongside mangrove forests. Studies
conducted in the Indian River Lagoon documented a catch of 376
individuals ranging from 122 to 840 mm over a 17-month period
from 1996 to 1998 (Kupschus & Tremain 2001).
Reproduction:
Reproduction for S. barracuda
occurs sexually through external fertilization. Sexual maturity
is reached between the second and third year for males, and
the third to fourth year for females. Barracudas do not exhibit
sexual dimorphism, and sex can only be determined upon examination
of the gonads. Adults spawn between April and October in southern
Florida (de Sylva 1963), releasing eggs and sperm into the water
column. Literature detailing spawning behavior in the great
barracuda is lacking. However, in similar species, females may
spawn several times in one season, releasing over 500,000 eggs
each time (de Sylva 1963).
Embryology:
Little is known about the embryology of
S. barracuda. De Sylva (1963) documented the collection
of eggs from the ovaries of females, describing them as translucent
and 0.74 to 0.81mm in diameter. However, these eggs were most
likely immature and all attempts to culture embryos in the laboratory
were unsuccessful.
IV. PHYSICAL TOLERANCES
Temperature:
Distribution of S. barracuda is
primarily restricted to tropical and warm temperate waters worldwide,
suggesting a narrow thermal tolerance in the species. In the
Indian River Lagoon, hunting activity and gut contents of the
great barracuda declined in cold/dry seasons. Laboratory studies
revealed less prey stalking activity in juveniles kept in water
below 15°C than in those maintained at 21-27°C (Fah
1976). Galloway (1941) observed high mortality in barracudas
in the Florida Keys during January 1940, when water temperatures
dropped to 6°C.
Salinity:
Juvenile S. barracuda are common
in estuaries where salinity may fluctuate seasonally and during
tidal cycles by = 20 ppt. Adults are found primarily in nearshore
and coral reef areas where salinities are stable at approximately
35 ppt.
V. COMMUNITY ECOLOGY
Trophic Mode:
Barracudas employ ram strike feeding, quickly
lunging to force prey to into the jaws where sharp teeth and
head shakes shear it into manageable pieces (Grubich et al.
2007, Porter & Motta 2004). The diet of S. barracuda
consists mainly of schooling fishes, however studies of gut
contents in both juveniles and adults have revealed solitary
fishes and small numbers of crustaceans, mollusks and plant
material (de Sylva 1963 & Fahs 1976). Prey selection is
indiscriminate and determined by the mouth length of the barracuda,
but certain prey items are found more frequently. In Florida,
approximately 70% of the diet of juvenile S. barracuda
is comprised of gobies, herrings, sardines and silversides (de
Sylva 1963). In the Indian River Lagoon, the dominant prey item
of young barracuda is the bay anchovy, Anchoa mitchilli
(Fah 1976). Nearshore and coral reef fishes such as ballyhoo,
triggerfishes and mullet are the primary prey of adult barracuda
(de Sylva 1963).
Predators:
The speed and size of adult S. barracuda
allows for few predators. However, juveniles and small adults
have been reported in the guts of the goliath grouper, Epinephelus
itajara, the dolphinfish, Coryphaena
hippurus and several species of tuna (de Sylva, 1963).
Habitats:
Juvenile barracuda are commonly found in
estuaries where they feed and take shelter in seagrass beds
and among mangrove prop roots (Fah 1976). Solitary individuals
or small groups of adults are typical on nearshore and coral
reefs (Gudger 1918).
Activity Time:
Fah (1976) found that S. barracuda
in the Indian River Lagoon are a diurnal species (active during
the day), feeding in seagrass and mangrove habitats two hours
after sunrise to about two hours before sunset. The great barracuda
shares a similar diet with the northern sennet, S. borealis,
which is a nocturnal feeder most active between 3:00 am and
approximately two hours before sunrise. Differences in activity
time between these two species are thought to be a method of
niche separation to reduce competition for food resources.
VI. SPECIAL STATUS
Special Status:
None
Economic Importance:
Although barracuda are consumed in small
quantities in Atlantic and Caribbean waters, the species is
not a major sport fish due mostly in part to its involvement
in ciguatera. Ciguatera, also known as ciguatoxic or ciguatera
fish poisoning, is a food-borne illness that affects humans
after the consumption of an infected fish. Ciguatoxins are natural
toxins that originate from microscopic marine algae, most notably
the marine dinoflagellate, Gamberdiscus toxicus (Bagnis
1980). The toxins are amplified through food webs as small fishes
and invertebrates consume the algae directly, and larger predators
prey on the primary consumers. Therefore, many of the most toxic
species are top predators such as the great barracuda, and consumption
of larger individuals pose a higher risk than juveniles. Signs
and symptoms of ciguatera include gastrointestinal, cardiovascular,
neurological and neuropsychiatric complications. These effects
arise approximately 6-24 hours after consuming infected fish
and usually resolve within 1-4 days (Friedman et al. 2008).
VII. REFERENCES
Bagnis, R, Chanteau, S, Chungue, E, Hurtel,
JM, Yasumoto, T & A Inoue. 1980. Origins of ciguatera fish
poisoning: A new dinoflagellate, Gamberdiscus toxicus
Adachi and Fukuyo, definitely involved as a casual agent. Toxicon
18: 199-208.
De Sylva DP. 1963. Systematics and life history of the great
barracuda. Univ. Miami, Coral Gables. 179 pp.
Fahs II RW. 1976. Feeding habits and food of the great barracuda
Sphyraena barracuda in the Indian River. Master’s Thesis.
Florida Inst. of Technology. 36 pp.
Friedman, MA, Fleming, LE, Fernandez, M, Bienfang, P, Schrank,
K, Dickey, R, Bottein, M, Backer, L, Ayyar, R, Weisman, R, Watkins,
S, Granade, R & A Reich. 2008. Ciguatera fish poisoning:
treatment, prevention and management. Mar. Drugs 6:
456-479.
Galloway JC. 1941. Lethal effect of the cold winter of 1939-40
on marine fishes at Key West, Florida. Copeia 1: 118-119.
Grubich JR, Rice AN & MW Westneat. 2008. Functional morphology
of bite mechanics in the great barracuda (Sphyraena barracuda).
Zoology 111: 16-29.
Gudger, EW. 1918. Sphyraena barracuda; its morphology,
habits and history. Pap. Tortugas Lab. 12: 53-108.
Kupschus, S & D Tremain. 2001. Associations between fish
assemblages and environmental factors in nearshore habitats
of a subtropical estuary. J. Fish. Bio. 58: 1383-1403.
Robins CR, Ray GC, and J Douglas. 1986. A Field Guide to Atlantic
Coast Fishes. The Peterson Field Guide Series. Houghton Mifflin
Co., Boston. 354 pp.
Porter HT and PJ Motta. 2004. A comparison of strike and prey
capture kinematics of three species of piscivorous fishes: Florida
gar (Lepisosteus platyrhincus), redfin needlefish (Strongylura
notata), and great barracuda (Sphyraena barracuda).
Mar. Biol. 145: 989-1000.
Russell, BC. 2002. Sphyraenidae. pp. 1807-1811. In: The living
marine resources of the Western Central Atlantic. Volume 3:
Bony fishes part 2 (Opistognathidae to Molidae), sea turtles
and marine mammals. Carpenter KE (ed.). FAO species identification
guide for fishery purposes and American Society of Ichthyologists
and Herpetologists special publication no. 5. FAO, Rome. pp.
1375-2127.
Report by: LH Sweat, Smithsonian Marine Station
at Fort Pierce
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Page last updated: 6 May 2009
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