Species Description: The redfin needlefish, Strongylura notata notata, is a member of the family Belonidae.
Fishes from this group are elongate with extended jaws that form a long, fragile beak (Robins & Ray 1986). They bear only one dorsal and one anal fin placed far back on the body, no finlets, and pelvic fins are on the abdomen. Scales are tiny, and the lateral line runs along the lower edge of the body. All species are bluish to greenish dorsally, with white or silver flanks and abdomen. The dorsal, caudal and anal fins of S. notata notata are orange to reddish. Both dorsal and anal fins exhibit 13-15 rays, and the opercle or gill cover bears a characteristic vertical black bar along its front edge. Like several other belonid species, the upper jaw is slightly shorter than the lower.
Potentially Misidentified Species: In addition to the redfin needlefish, two other species of Strongylura are found in the IRL: the Atlantic needlefish, S. marina; and the timucu, S. timucu. Both species reach 61 cm in length. The Atlantic needlefish has a bluish caudal fin and pale head (Robins & Ray 1986). Dorsal and anal fin ray counts are 14-17 and 16-20, respectively. The timucu is similar in appearance to S. marina, but with a broad dusky stripe behind the eye and a darker area in front of the eye. Both species lack the orange/red coloration on the fins and the dark band on the gill cover characteristic of S. notata notata.
Regional Occurrence: The range of S. notata notata extends from Florida and Bermuda throughout the Caribbean to Central America (Robins & Ray 1986). It is a coastal species, preferring bays and inlets including mangrove and seagrass habitats.
IRL Distribution: The redfin needlefish is found throughout the IRL system, and is most abundant in mangrove and seagrass habitats.
Age, Size, Lifespan: The maximum age of the redfin needlefish is unknown, and lifespan and growth may vary with food availability and environmental factors such as temperature, salinity and dissolved oxygen. The maximum reported size for S. notata notata is 61 cm, but most specimens do not exceed 38 cm (Robins & Ray 1986).
Abundance: The redfin needlefish is a common inhabitant of mangrove and seagrass ecosystems, swimming alone or in small schools. Trawl data for Florida Bay populations report catches of S. notata notata exceeding 99.9 individuals per 1,000 m² in some locations (Powell et al. 2007).
Reproduction & Embryology: Little information is documented for the life history of S. notata notata. Breder (1959) reported that the species prefers to spawn among the prop roots of the red mangrove, Rhizophora mangle. Fertilized eggs are demersal, with external adhesive filaments attached to the chorion, or outer membrane. The approximate diameter of eggs at hatching is 12 mm. Spawning most likely occurs in all seasons, but is elevated in spring and summer, as evidenced by the surge of juveniles caught throughout Florida Bay in May through July (Powell et al. 2007).
Temperature: The redfin needlefish is a tropical to subtropical species, preferring warm coastal waters. Little information exists concerning the temperature tolerances for the species, but individuals have been collected from waters ranging from 21 to 32°C (Arceo-Carranza et al. 2004). High spawning occurrences in the spring and summer months (Powell et al. 2007) may be due in part to increased water temperature.
Salinity: As a coastal and estuarine species, S. notata notata experiences wide fluctuations in salinity seasonally as a result of increased precipitation, runoff and evaporation. Individuals can thrive in a large range of salinities, and have been collected from waters between 0 and 110 ppt (Arceo-Carranza et al. 2004, Vega-Cendejas & de Santillana 2004). Like S. marina, this species is known to enter freshwater areas (Robins & Ray 1986).
Trophic Mode: All needlefish species are predators, feeding on a variety of pelagic and demersal organisms (Arceo-Carranza et al. 2004, Robins & Ray 1986). The prey of the redfin needlefish includes:
Fishes, especially other belonids, pipefishes, mullet, anchovies and cichlids; crustaceans, including shrimps, crabs and amphipods; polychaete worms; and insects (Arceo-Carranza et al. 2004, Chavez-López 1998, Ley et al. 1994, Reid 1954).
The feeding behavior of S. notata notata is similar to that of the great barracuda, Sphyraena barracuda. It lunges and strikes at its prey via "ram feeding" (Porter & Motta 2004). During this process, the needlefish orients itself parallel to its prey before quickly striking to pin the animal in its jaws. A series of rapid movements in which the needlefish releases the prey, lunges again and recaptures the prey serves to turn the food to a head-first orientation. Once the organism is properly positioned, it is consumed through suction transport. This food positioning behavior has only been observed for fish prey, and is most likely less crucial during the capture of invertebrates, which vary greatly in body form.
Predators: Redfin needlefish are likely prey for a variety of larger birds and fishes. However, like many other shallow-water organisms, S. notata notata employs countershading (Robins & Ray 1986) to lower predation risk. Blue to green coloration on the dorsal surface allows the fish to blend in with the surrounding water, thereby camouflaging itself from overhead predators like birds. Contrasting white or silver on the abdomen blends with the color of the sky, concealing S. notata notata from predators that may attack from below.
Associated Species: While S. notata notata has no known obligate relationships with other species, it is commonly found with a variety of other co-occurring organisms in seagrass and/or mangrove ecosystems.
Arceo-Carranza, A, Franco-López, J, Waggy, GL & R Chavez-López. 2004. Trophic comparison of two species of needlefish (Belonidae) in the Alvarado lagoonal system, Vercruz, Mexico. Gulf Carib. Res. 16: 81-88.
Breder, CM, Jr. 1959. Observations on the spawning behavior and egg development of Strongylura notata (Poey). Zoologica. 44: 141-148.
Chavez-Lopez, R. 1998. Caracterización ecológica de la comunidad de peces asociada a praderas de Ruppia maritima en el Sistema Lagunar de Alvarado, Veracruz. Master's Thesis. Facultad de Ciencias, Universidad Nacional Autónoma de Mexico. 145 pp.
Ley, JA, Montague, CL & CC McIvor. 1994. Food habits of mangrove fishes: a comparison along estuarine gradients in northeastern Florida Bay. Bull. Mar. Sci. 54: 881-899.
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.
Powell, AB, Thayer, G, Lacroix, M & R Cheshire. 2007. Juvenile and small resident fishes of Florida Bay, a critical habitat in the Everglades National Park, Florida. NOAA Professional Paper NMFS 6: 105-108. National Marine Fisheries Service. Seattle, WA. USA.
Reid, GK, Jr. 1954. An ecological study of the Gulf of Mexico fishes in the vicinity of Cedar Key, Florida. Bull. Mar. Sci. 4: 1-94.
Robins, CR & GC Ray. 1986. A field guide to Atlantic coast fishes of North America. Houghton Mifflin Co. New York. USA. 354 pp.
Sogard, SM, Powell, GVN & JG Holmquist. 1989. Utilization by fishes of shallow, seagrass-covered banks in Florida Bay: 1. Species composition and spatial heterogeneity. Environ. Biol. Fish. 24: 53-65.
Vega-Cendejas, ME & MH de Santillana. 2004. Fish community structure and dynamics in a coastal hypersaline lagoon: Rio Lagartos, Yucatan, Mexico. Estuar. Coast. Shelf Sci. 60: 285-299.