Species Description: The body of Sphyraena barracuda is elongate to slightly compressed with small, cycloid scales. The head is long and pointed with a large, nearly horizontal jaw fitted with variably-sized flattened or conical canine teeth that extend to the roof of the mouth. Two short dorsal fins are widely separated, with the first located opposite or directly behind the pelvic fins, and the second opposite the anal fin.
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).
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.
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.
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.
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.
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).
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.