EGG AND LARVAL DEVELOPMENT OF THE SPOT, 

 LEIOSTOMUS XANTHURUS (SCIAENIDAE)' 



Allyn B. Powell and Herbert R. Gordy^ 



ABSTRACT 



The egg and larval development of the spot, Leiostomus xanthurus, was described mainly from 

 laboratory-reared specimens. Egg diameters averaged 0.80 mm and ranged from 0.72 to 0.87 mm. The 

 number of oil globules varied, but coalesced during development. Oil globule diameters of eggs with one 

 globule averaged 0.21 mm and ranged from 0.18 to 0.28 mm. Newly hatched larvae measured 1.6-1.7 

 mm standard length, had a single oil globule located at the posterior margin of the yolk sac, and were 

 inconspicuously pigmented. Late yolk-sac larvae developed a characteristic pigment pattern of a single 

 row of melanophores along the ventral midline that persisted throughout the larval period. An 

 important pigment pattern — embedded pigment at the anterior of the gut — was first observed in clear 

 and stained late flexion larvae (2.9 mm standard length). Vertebrae and anal fin pterygiophore counts 

 were considered useful in separating spot from other sciaenids. Vertebral counts (25) were established 

 by 4.6 mm standard length, and precaudal (lOi and caudal (15) vertebrae were recognized at 5.1 mm 

 standard length. Anal fin pterygiophores which numbered two fewer than the number of anal fin 

 elements were established at 6.3 mm standard length. 



The spot, Leiostomus xanthurus (Lacepede), is a 

 commercially important sciaenid found along the 

 Northwest Atlantic and Gulf of Mexico coasts from 

 Massachusetts Bay to the Bay of Campeche 

 (Johnson 1978). Spot spawns in offshore waters 

 during late fall and early winter, throughout its 

 range (Hildebrand and Cable 1930; Nelson 1969). 

 The larvae are transported towards shore and into 

 estuaries which serve as nursery areas (Fahay 

 1975; Chao and Musick 1977). 



The eggs and yolk-sac larvae of spot have not 

 been described. Pearson (1929) briefly described 

 larvae ranging from 7 to 15 mm. Hildebrand and 

 Cable ( 1930 ) described larvae in greater detail and 

 attempted to distinguish spot larvae from mor- 

 phologically similar larvae of Atlantic croaker, 

 Micropogonias undulatus (the generic name 

 change from Micropogon follows Chao 1978). Hil- 

 debrand and Cable (1934) summarized early life 

 history data for 13 species of sciaenids, including 

 spot, but the keys they prepared were limited since 

 the early developmental stages for many species 

 were unknown. Lippson and Moran (1974) and 

 Johnson (1978) summarized early life history 



'Contribution No. 80-27B of the Southeast Fisheries Center 

 Beaufort Laboratory, National Marine Fisheries Service, 

 NOAA. 



^Southeast Fisheries Center Beaufort Laboratory, National 

 Marine Fisheries Service, NOAA, Beaufort, NC 28516. 



Manuscript accepted FebruaQf 1980. 

 FISHERY BULLETIN: VOL. 78, NO. 3, 1980. 



studies on sciaenids and included previously un- 

 published illustrations useful in separating spot 

 and croaker larvae. Fruge and Truesdale (1978) 

 and Powles and Stender (1978) described devel- 

 opmental stages of spot larvae from the Gulf of 

 Mexico and the South Atlantic Bight. Fruge and 

 Truesdale provided comparative data useful for 

 separating larvae of spot from larvae of Atlantic 

 croaker, while Powles and Stender emphasized 

 characters useful in separating early sciaenid lar- 

 vae. 



In this paper we describe the life history of spot 

 from egg to juvenile, using the dynamic approach 

 of Ahlstrom and Ball (1954). Our objective is to 

 provide descriptive information useful in identifi- 

 cation and classification, as patterns of larval 

 development and larval anatomical features may 

 provide keys to possible relations among groups 

 ( Aprieto 1974). Furthermore, studies of variations 

 of these patterns and features could provide keys 

 to how environmental factors may affect larval 

 development. 



METHODS 



Spot used for spawning were collected from a 

 commercial long-haul seine in Back Sound off 

 Harkers Island, N.C., during their spawning mi- 

 gration to the ocean. Eggs were obtained from fish 

 using an induced spawning technique developed 



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