Ingress of Postlarval Gag, Mycteroperca-Microlepis (Pisces, Serranidae), through a South-Carolina Barrier-Island Inlet

Postlarval gag, Mycleroperca microlepis, collected with fixed neuston nets at Price Inlet, South Carolina, entered the barrier island inlet during late spring-early summer. The mean age of M. microlepis collected during 5 years of sampling was 43 days; mean standard length was 15 mm. Postlarvae were most abundant in near-surface waters during night flood tides and generally did not leave the inlet on subsequent ebb tides. Analysis of back-calculated fertilization dates, as determined from presumed daily growth increments in lapilli from postlarvae, indicated that putative peaks in spawning were correlated with lunar phase. Estimates of the magnitude of ingress and the extremely rare occurrence of young of the year offshore suggest that estuarine ingress and residence is probably a consistent and integral part of the early life history of M. microlepis off South Carolina. The gag, Mycteroperca microlepis (Goode and Bean, 1880), is a large (up to 1,200 mm TL) epinepheline serranid found in coastal waters of the western Atlantic from New York to Brazil, including the Gulf of Mexico, Cuba, and Bermuda (Smith, 1971; Hardy, 1978). Along the southeastern coast of the United States and the Gulf of Mexico, the gag is often an important component of recreational and commercial fisheries. Although certain aspects of the biology of the adults have been examined (McErlean, 1963; McErlean and Smith, 1964; Huntsman and Dixon, 1976; Manooch and Haimovici, 1978; Collins et al., 1987), little is known ofthe early life history of M. microlepis or, for that matter, other grouper species (Hardy, 1978; Leis, 1986). Characters useful for generic and specific identification of American grouper larvae have been described only recently (Johnson and Keener, 1984) and the larvae of many species, particularly those of Mycteroperca, remain indistinguishable. Although the Serranidae has been reported to be one of the most abundant families taken in ichthyoplankton collections from the southeastern coast of the United States, the Gulf of Mexico, and the Caribbean (Powles and Stender, 1976; Finucane et al., 1979; Houde et al., 1979; Richards, 1984; McGowan, 1985), the subfamily Epinephelinae is nowhere abundant in the plankton (Houde, 1982; Leis, 1986), and it is therefore difficult to make valid, meaningful comparisons of their distribution and relative abundance. Newly settled young of most species are cryptic inhabitants of structurally complex bottoms and are rarely collected by conventional sampling methods, Off the southeastern coast of the United States, adult M. microlepis are most frequently found in association with live bottom (sponge-coral) habitats (Struhsaker, 1969; Wenner, 1979; 1983; Powles and Barans, 1980) in depths from 25 to 100 m from 40 to 70 km offshore. Small juveniles, presumably young of the year, have been collected in estuarine waters (Hoese et al., 1961; McErlean, 1963; Adams, 1976; Manooch and Haimovici, 1978) but the generality and extent of their estuarine association has not been investigated. McErlean (1963) reported that young gag occur inshore in the Gulf of Mexico 3 to 4 months after the time of spawning and noted that "a vigorous collecting program aimed at obtaining