Species Description: The ladyfish, Elops saurus, is a medium-sized fish with an elongate body covered with small, silvery scales. The overall body color is silver, bluish dorsally with yellowish lower sides and a yellow to white ventral surface. The head is small and pointed, with a large terminal mouth whose maxillary extends well behind the eye. The symmetrical caudal lobes of the tail are long and slender, and the dorsal fin inserts just behind the insertion point of the pelvics (Hoese and Moore 1977, Zale and Merrifield 1989).
The scale count along the straight lateral line is 103-120, the dorsal ray count is 21-25, and the anal ray count is 14-17 (Hoese and Moore 1977).
Potentially Misidentified Species: Ladyfish belong to an ancestral order of bony fish called the Elopiformes. Tarpon (Megalops atlanticus) belong to the same order, and both species are placed in the same family, Elopidae. Both of these species are herring-like in appearance, but can be distinguished from the clupeids not just by size, but by the presence of a gular plate-a bony structure located at the center of the lower jaw. Ladyfish can be differentiated from tarpon by a smaller body size, thinner profile, and finer body scales (Hoese and Moore 1977).
Bonefish (Albula vulpes) belong to Order Elopiformes as well, but they are placed into a separate family, the Albulidae. Bonefish lack the gular plate that the elopids possess, the inferior mouth is smaller than that of ladyfish, the snout somewhat more rounded, and the body profile not as thin (Hoese and Moore 1977, Robbins et al. 1986).
Larval ladyfish develop into an elongate, flat, nearly transparent larval type known as a leptocephalus. The leptocephalus is an ancestral larval form that today is found only in ladyfish, tarpon, bonefish, and a number of eel families. All of these species are considered to be among the more ancestral of living teleost fish groups.
Regional Occurrence: Elops saurus can be found in the western Atlantic from southern New England (but uncommon north of Cape Hatteras, NC) south to Bermuda, Florida, and throughout the Gulf of Mexico to southern Brazil (Zale and Merrifield 1989, FWRI 2006). The species also occurs in the western Pacific and the Indian Ocean (Bigelow and Schroeder 1953).
Two phenotypically distinct, sympatric (overlapping distributions) ladyfish stocks occur in Florida waters (McBride and Horodysky 2004). The more northern stock is characterized by a high myomere count while the more southern stock exhibits a low myomere count (Smith 1989).
IRL Distribution: Ladyfish occur throughout the IRL system. McBride at al. (2001) confirm that the species is broadly distributed in both the Indian River and Banana River basins throughout the year, with larger individuals (> 300 lm SL) more common in the Banana River basin.
Age, Size, Lifespan: Zale and Merrifield (1989) report that ladyfish attain a maximum length of nearly 1 m (but usually less than 60 cm). Although they can reach a maximum weight of nearly 7 kg, most individuals are less than 1.5 kg (Hoese and Moore 1977).
Palko (1984) suggests ladyfish can live as long as 6 years.
Abundance: The abundance of Elops saurus in Florida is sufficient to support a recreational fishery as well as an incidental commercial fishery. The estimated total Florida landings (commercial and recreational) of the species in 2005 exceeded 725,000 kg (FWRI 2006).
Reproduction: Ladyfish are known to be offshore spawners (McBride et al. 2001). Field larval collections analyzed by Hildenbrand (1943) suggest that offshore spawning occurs in the fall.
McBride et al. (2001) indicated that few individuals older than 2-3 years were collected in surveys conducted in Tampa Bay and in the Indian River Lagoon, and nearly all inshore fish of this age were reproductively immature. The authors agree with other published reports (e.g., Hildebrand 1963, Palko1984) suggesting that ladyfish leave the estuaries at 2-3 years of age to mature and spawn offshore.
Embryology: Post yolk-sac animals progress through three distinct larval stages (Zale and Merrifield 1989). Stage I is the leptocephalus stage in which individuals are 40-45 mm long (SL), ribbonlike and colorless, with a small head and small fins. Large, fang-like teeth are present though, paradoxically, the gut is not fully formed. Gills and red blood cells are absent. Gas exchange occurs across the body surface and nutrient uptake probably occurs in this manner as well (i.e., osmotrophy).
Stage II larvae decrease measurably in length (SL = 18-20 mm) compared to Stage I animals, and they become less ribbon-like over time. Stage III larvae again increase in length before undergoing metamorphosis into the juvenile stage at around SL 30-35 mm. Morphological changes accompanying this transition include an increase in body depth, head and snout length, fin height/size, and the gradual emergence of body colors analogous to those of juvenile and adult animals (Hildebrand 1934, Zale and Merrifield 1989).
Research reports provide varying larval duration estimates, with some authors noting the combined duration of Stages II and III as just 9 days (Gehringer 1959a), while other investigators observed combined Stages II and III durations of roughly 71 days (Alikunhi and Rao 1951).
McBride et al. (2001) observed that numbers of new cohorts of late-metamorphic ladyfish larvae in Tampa Bay peaked in April. In the Indian River Lagoon, these authors note the presence of early- and mid-metamorphic larvae from at least December to May, and a peak concentration of late-metamorphic larvae in the spring.
Temperature: Zale and Merrifield (1989) consider ladyfish to be a thermophilic species. It has been involved in documented cold-related fish kills in the Indian River Lagoon (Snelson and Bradley 1978) and elsewhere in Florida (Springer and Woodburn 1960). Ladyfish seem to be slightly more tolerant of cold snaps than tarpon, however, and are less frequently harmed in thermal kills (Storey 1937).
Adults have been collected from waters ranging from 11°C to 35°C, while early-stage larvae are found exclusively in warm oceanic waters at temperatures of 22.2-30°C (Eldred and Lyons 1966, Zale and Merrifield 1989).
Salinity: Elops saurus is found in marine and brackish waters throughout most stages of their life (Nelson 1984), although early larvae appear to be confined to oceanic salinities (Smith 1980). Juveniles are typically found at moderate salinities of around 23-25 ppt (McBride et al. 2001), but they have also been collected from a much broader range of 0-45 ppt (Govoni and Merriner 1978, Thompson and Deegan 1982).
Adult ladyfish have been collected from Florida waters at salinities as low as 0.5 ppt (Zale and Merrifield 1989).
Dissolved Oxygen: Although they are not obligate air-breathers like tarpon, ladyfish do appear to be relatively tolerant of hypoxia. Rose et al. (1975) record ladyfish inhabiting a Louisiana coastal impoundment that experienced an oxygen minimum concentration of 2.0 mg/L.
Trophic Mode: As adults, Elops saurus are primarily piscivorous midwater predators, with various investigators reporting that fish accounted for between 34 and 94% of stomach contents (FWRI 2006). Decapod crustaceans are also important components of the diet of ladyfish.
Stage II and III ladyfish larvae feed almost exclusively on zooplankton. As they grow, juveniles take in increasing amounts of larger prey items such as small fish and shrimp as they grow, simultaneously reducing their reliance on zooplankton (Harrington and Harrington 1961).
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: Relatively large size protects adult ladyfish from most would-be predators, although some mortality occurs via predation by piscivorous birds, sharks, dolphins, and alligators (Zale and Merrifield 1989).
Pelagic eggs and larvae are susceptible to predation by small fish and carnivorous zooplankton (Zale and Merrifield 1989).
Parasites: Corkum (1959) reported parasitic tremetodes of genera Bucephalus and Prosorhynchus living within the intestine of ladyfish collected from the Mississippi Gulf coast.
Habitats: Ladyfish can be found in several coastal and estuarine habitats, including seagrass beds, mangrove marsh, and sand flats. Settlement-stage larvae and juveniles occur along beaches and in rivers, canals, and impounded estuarine marshes (Gilmore et al. 1981).
Activity Time: Diel activity studies conducted by Sogard et al. (1989) indicate that Elops saurus exhibits a high degree of nocturnal activity, evident as increased capture rates occurred starting at dusk and continued through the first few hours after dark before declining through the later nighttime hours. These authors report that E. saurus was captured exclusively at night at Florida Bay sampling sites with high water clarity, but was caught in low numbers during daylight hours as well where water clarity was low.
Economic Importance: Although ladyfish are not widely sought as an edible species owing to its boniness, a moderate commercial fishery does exist in Florida. Total Florida landings of ladyfish in 2005 exceeded 725,000 kg, with 85% of that total landed commercially (FWRI 2006). 96% of the 2005 catch was taken on the Florida Gulf coast.
The 1995 Florida inshore net ban severely impacted the commercial ladyfish fishery. It may also have allowed stocks to rebound after several decades of exploitation; landing totals in 2005 were 25% higher than the average landings from the previous 5 years (FWRI 2006).
A significant recreational ladyfish fishery exists throughout coastal Florida, which exhibits many of the same sportfish attributes as tarpon but can be caught on light tackle.
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