Species Description: The Atlantic needlefish, Strongylura marina, is a small- to medium-sized, elongate, somewhat gar-like carnivorous fish with the upper and lower jaws elongated into a pointed beak armed with hundreds of small, sharp teeth. Body coloration is greenish to blue-green above and silvery below and the body is covered with small scales (Hoese and Moore 1977). Despite their superficial resemblance to gars, needlefish are more closely related to flying fish (Family Exocoetidae), and the leaping and surface-skittering behavior of S. marina when alarmed or pursuing prey is well-documented (Collette 1977, Helfman et al. 1997).
Hoese and Moore (1977) give soft ray counts for S. marina as: dorsal = 14-17, anal = 16=20, pectoral = 10-12 (typically 11).
Potentially Misidentified Species: Two other common and very similar species of western Atlantic Strongylura occur alongside Strongylura marina in the IRL: Strongylura notata and Strongylura timucu. Until the late 1960s, S. timucu was largely considered to be synonymous with S. marina (Berry and Rivas 1962). Collette (1968) notes that S. notata differs from S. marina and S. timucu in having fewer anal rays and fewer predorsal scales, and internal examination also reveals fewer vertebrae and other distinguishing skeletal features. Internal examination also reveals that both gonads are developed in S. tumucu, while only the right gonad is developed in S. marina. Typically, S. timucu is also somewhat darker in coloration than S. marina (Hoese and Moore 1977).
Strongylura notata differs externally from S. marina, possessing 13-15 dorsal rays and 13-16 anal rays (Hoese and Moore 1977).
Three additional genera of belonid fish also occur in the western Atlantic, Ablennes, Belone, and Tylosurus (Berry and Rivas 1962).
Regional Occurrence: Strongylura marina occurs in the western Atlantic from Maine to southern Brazil, throughout the coastal Gulf of Mexico, and the western Caribbean Sea including Cuba and Jamaica. It also occurs in a number of coastal rivers and streams and is capable of ascending well upstream into fresh water (Hoese and Moore 1977, Boschung 1992, Nordlie 2003).
Fuller (2008) indicates that S. marina also occurs as an introduced species within the portions of the Tennessee River drainage basin in Alabama and Tennessee. Introduction was reportedly by means of an artificial canal that that was opened in 1985 (Etnier and Starnes 1993).
Nordlie (2003) reports that S. marina is among the 15 most widely distributed fish species from Atlantic and Gulf Coast estuaries of North America.
IRL Distribution: Strongylura marina occupies estuarine and coastal waters throughout the IRL region.
Age, Size, Lifespan: IGFA (2001) reports a maximum total length for the species as 111 cm and a maximum published weight of 2,340 g, although most specimens are much smaller than this. Hoese and Moore (1977) indicate a more typical maximum length of 61 cm.
Abundance: Although widely distributed, Atlantic needlefish typically do not occur as numerical dominants of most ichthyofaunal collections in which they occur (e.g., Orth and Heck 1980, Idelberger and Greenwood 2005).
Reproduction: Strongylura marina is oviparous, and the demersal eggs may be found attached to submerged plants and other suitable surfaces by long filamentous tendrils on the egg surfaces (Breder and Rosen 1966). Spawning activity is likely confined to shallow inshore habitats with algal mats or other suitable submerged vegetation (Berry and Rivas 1962, Foster 1974). The fertilized eggs are spherical and large, averaging around 3.5 mm in diameter (Breder and Rosen 1966, Hardy 1978).
Reproductive seasonality is dictated by region. Foster (1974) reports a late spring to early summer spawning season in the Potomac River, while Hardy (1978) notes the appearance of near-ripe females in mid-February in Texas.
The internal reproductive anatomy of Strongylura marina is unusual in that only the right gonad is developed in mature animals (Hoese and Moore 1977). Hardy (1978) suggests that reproductive maturity occurs in the second year of life.
Embryology: The newly hatched larvae are large, averaging 9.2-14.4 mm TL (Foster 1974, Hardy 1978). Boughton et al. (1991) describe ontogenic changes in jaw morphology exhibited by Strongylura marina and other needlefish species. Newly hatched larvae possess short jaws of equal length, and juveniles of 35-50 mm or less exhibit a "halfbeak" form in which the upper jaw remains short but the upper jaw is elongated. The upper jaw elongates in time and larger juveniles soon take on a "needlenose" morphology in which the upper and lower jaws are essentially equal in length.
Temperature: Warlen and Burke (1990) note that Strongylura marina is among the predatory fish that occupy North Carolina estuaries during warmer months but migrate out of the estuaries with the fall onset of colder temperatures. Holt and Holt (1983) also indicate that S. marina is at least somewhat susceptible to cold temperature kills and they list the species as one that suffered high morbidity during a 1982 cold snap at Port Aransas, TX.
Salinity: The euryhaline nature of Strongylura marina is well documented. Boschung and Hemphill (1960) noted that individuals have been collected more than 600 km up the Black Warrior River near Tuscaloosa, Alabama. Froese and Pauly (2008) and Fuller (2008) indicate that Atlantic needlefish regularly venture into fresh water, and Mettee et al. (1996) present evidence supporting the claim that spawning adult populations occur upstream in several rivers in the southeastern United States. Collette (1974) suggests that freshwater populations of S. marina are self-sustaining within Florida's St. John's River system, and Swift et al. (1977) indicated the possible existence of a permanent population in the Apalachicola River.
Lovejoy and Collette (2001) note the existence of several freshwater species of Strongylura and other belonids and hypothesize that they are the result of multiple independent transitions to neotropical freshwater habitats.
Trophic Mode: Needlefishes are swift predators that employ a ram-feeding, active pursuit predation strategy similar to that of gars and barracudas. Gut analysis of Strongylura marina from the northeastern Gulf of Mexico conducted by Luczkovich et al. (2002) confirm that adults are predominantly piscivorous in nature. Carr and Adams (1973) note an ontogenetic dietary shift in which juveniles from 35-50 mm SL ate mostly (70%) shrimp, mysids, and amphipods and 30% fish, while large individuals were almost entirely piscivorous. Boughton et al. (1991) report that this dietary shift coincides with the ontogenetic change in jaw morphology (see above) from a "halfbeak" form (lower jaw longer than upper jaw) to the "needlenose" form (upper and lower jaws equal in length) typical of adults.
Competitors: Potential competitors with Elops saurus for food resources is likely to include a number of similarly sized piscivorous species, including tarpon, bonefish, needlefish, and others.
Predators: Strongylura marina and other needlefish are common components in the diets of large piscivorous fish such as tarpon, Megalops atlanticus (Zale and Merrifield 1989). Gunter (1942) indicates that S. marina is an occasional component in the diet of bottlenose dolphin (Tursiops truncatus) in Texas, and Cortes and Gruber (1990) list it as a component in the diet of juvenile lemon sharks (Negaprion brevirostris).
The surface-swimming tendencies of S. marina also leave the species vulnerable to avian predators. Gordon et al. (2000) report that S. marina was one of the two fish species most frequently fed to Chesapeake Bay fledgling black skimmers (Rynchops niger) by their parents. The authors note that an 80% decline in S. marina and Atlantic menhaden (Brevortia tyrannus) over the previous two decades coincided with an equally precipitous drop in skimmer numbers during that same period. McEwan and Hirth (1980) report Atlantic needlefish remains were identifiable in droppings collected from in and around the nests of bald eagles (Haliaeetus leucocephalus) in north-central Florida.
Parasites: Bere (1936) reported several parasitic copepods that have been observed on Strongylura from the Florida Gulf coast. Williams and Rogers (1972) describe three species of monogenetic tremetodes of genus Ancyrocephalus that are known to parasitize the gills of S. marina.
Habitat: The Atlantic needlefish is a common inhabitant of shallow coastal and estuarine habitats, including within mangrove margins and swimming over and around seagrass meadows. Orth and Heck (1980) note that S. marina is one of the larger mobile predatory fish found in lower Chesapeake Bay Eelgrass (Zostera marina) meadows, and Klassen (1998) found it a notable component of Indian River lagoon shoreline habitats. It spends most of its time swimming at the surface using undulating anguilliform (eel-like) body waves to propel itself (Liao 2002).
The countershaded body coloration of Atlantic needlefish is an adaptation that is typical for a species that lives near the water's surface (Randall 1983).
Activity Time: Active Strongylura marina may be encountered during both day and night. Sogard et al. (1989) reported that there was no consistent diel pattern observed in the congener S. notata in Florida Bay, and suggested that activity time may be more related to tidal patterns. The same may hold for this species.
Economic Importance: Strongylura marina appears to be of little economic importance in Florida. It is a minor, incidental component of commercial and recreational fisheries.
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