DEVELOPMENT AND EARLY LIFE HISTORY OF THE 

 NORTHERN SENNET, Sphyraena borealis DeKAY 

 (PISCES: SPHYRAENIDAE) REARED IN THE LABORATORY' 



Edward D. Houde^ 



ABSTRACT 



Eggs and larvae of the northern sennet, Sphyraena borealis DeKay, are described from laboratory- 

 reared specimens. Fertilized eggs were collected on the edge of the Florida Current near Miami in 

 December 1969. Larvae were 2.6 mm SL (standard length) at hatching and 13.5 mm SL at 21 days 

 after hatching. Head and snout length increased rapidly relative to standard length as larvae grew. 

 A fleshy tip developed on the lower jaw when larvae were longer than 5 mm SL. Teeth also first 

 appeared at about 5 mm SL. Myomere and vertebral numbers were constant at 24. Ossification of 

 the axial skeleton began in the cephalic region and proceeded caudad as growth occurred. Fin ray 

 complements were complete at about 13.5 mm SL. Pigmentation during development is described and 

 illustrated. Behavior of laboratory-reared S. borealis larvae is discussed. Several wild-caught post- 

 larvae were used to extend the descriptive series and helped to validate the identification of the lab- 

 oratory-reared larvae. 



Little is known about early development of bar- 

 racudas (Sphyraenidae) in the Western Atlantic 

 Ocean. Larvae of the northern sennet (also 

 called northern barracuda) , Sphyraena borealis 

 DeKay, recently were reared in the laboratory, 

 and the eggs, yolk-sac larvae, and early post- 

 larval stages are described in this report from 

 a series of preserved specimens, providing the 

 first description of this species in its earliest life 

 stages. De Sylva (1963) described some post- 

 larval S. borealis and presented keys to identify 

 the postlarvae of western North Atlantic sphyr- 

 aenids longer than 5.5 mm SL (standard length) . 

 Some confusion exists regarding the syste- 

 matic relation of S. borealis and the similar S. 

 picudilla Poey (southern sennet). The two spe- 

 cies are regarded by de Sylva (personal commu- 

 nication) as valid species, separable on minor 

 morphometric characters in adults. Briggs 



^ Contribution No. 202, National Marine Fisheries 

 Service, Southeast Fisheries Center, Miami Laboratory, 

 Miami, FL 33149. 



^ Contribution No. 1452, University of Miami, Rosen- 

 stiel School of Marine and Atmospheric Science, Miami, 

 FL 33149. 



^ National Marine Fisheries Service, Southeast Fish- 

 eries Center, Miami, FL 33149; present address: Divi- 

 sion of Fisheries and Applied Estuarine Ecology, Rosen- 

 steil School of Marine and Atmospheric Science, 10 Rick- 

 enbacker Causeway, Miami, FL 33149. 



(1958) reported S. borealis to be distributed 

 nearshore from Bermuda and Massachusetts to 

 Panama, including the north central Gulf of 

 Mexico. Adults of 5. borealis from southern 

 Florida intergrade in many characters toward 

 those of S'. picudilla (de Sylva, personal com- 

 munication). Postlarvae reared in the labora- 

 tory during this study always closely resembled 

 the S. borealis described by de Sylva (1963). 



The eggs and yolk-sac larvae of Sphyraena 

 argentea Girard from the eastern Pacific were 

 described by Barnhart (1927). Orton (1955) 

 also described S. argentea eggs and yolk-sac 

 larvae as well as older larvae of about 4 and 7 mm 

 TL (total length). Eggs and young larvae of 

 S. pinguis Gunther from the western Pacific 

 were described by Shojima, Fujita, and Uchida 

 (1957), and their development was reviewed by 

 Uchida et al. (1958) . Development of S. sphyr- 

 aena Linnaeus collected in the Mediterranean 

 was summarized by Vialli (1956), and illustra- 

 tions of some stages were presented by Lo Bianco 

 (1956). Development of S. barracuda (Wal- 

 baum), commencing with postlarval stages, was 

 discussed by de Sylva (1963). Except for the 

 material on S. sphyraena, complete develop- 

 mental series appear to be lacking for barra- 

 cudas. My specimens of S. borealis provide a 



Manuscript accepted September 1971. 



FISHERY BULLETIN: VOL. 70, NO. 1, 1972. 



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