LARVAL DEVELOPMENT OF THE SCUP, STENOTOMUS CHRYSOPS 



(PISCES: SPARIDAE) 1 



Carolyn A. Griswold 2 and Thomas W. McKenney 3 



ABSTRACT 



Larval scup, Stenotomus chrysops (Linnaeus 1766), were reared from eggs hatched in an aquarium. 

 Measurements of morphological features for 88 specimens from 2.0 to 16.9 mm SL indicate that growth is 

 gradual and continual with no well-defined changes in relative body proportions. Twenty-four myomeres are 

 present in larvae, agreeing with published reports of vertebrae numbers in adult scup. Ossification begins 

 first in the skulls of 6.1 mm SL larvae, and by 7.0 mm SL the vertebrae, neural spines, and fin rays are begin- 

 ning to ossify. Ossification is nearly complete in 18.7 mm SL juveniles. Three preopercular spines are present 

 in 4.1 mm SL specimens; the numbers of spines increase and by 16.9 mm SL the preopercular margin is 

 serrate. Median fin development occurs at 4.1 mm SL, all fins are present in 8.8 mm SL larvae, and a full com- 

 plement of rays are observed by 12.8 mm SL. Larvae are completely scaled by 13.0 mm SL. 



Scup, Stenotomus chrysops (Linnaeus 1766), the only 

 common sparid in southern New England waters, is a 

 popular sport and commercial fish in spring and sum- 

 mer. Their range is from South Carolina to Sable 

 Island, Nova Scotia, although they are uncommon 

 north of Cape Cod (Breder 1948; Bigelow and 

 Schroeder 1953; Leim and Scott 1966). Scup move 

 inshore in schools in early April in the Chesapeake 

 Bay area and in May north to Cape Cod. Most scup 

 spend the summer in bays or within 8-10 km of the 

 coast where they spawn from May to August with a 

 peak in June in Narragansett Bay (Perlmutter 1939; 

 Bigelow and Schroeder 1953; Wheatland 1956; Her- 

 man 1963). In late October scup begin to move 

 offshore to depths of 40-100 m. Commercial catches 

 between January and April indicate that many scup 

 winter off Virginia and North Carolina (Neville and 

 Talbot 1964; Smith and Norcross 1968). 



Despite the commercial importance and abundance 

 of this species, only one description of the eggs and 

 larvae exists (Kuntz and Radcliffe 1917). This de- 

 scription, which has been paraphrased several times, 

 and the accompanying illustrations, which have been 

 reprinted several times, provide no information on 

 osteological development nor do they present meris- 

 tic and morphometric data. Consequently we under- 

 took to rear larvae from laboratory-spawned eggs to 

 provide specimens for a more complete description 

 which would be useful for identification of wild 

 larvae. 



'MARMAP Contribution MED/NEFC 81-03. 



2 Northeast Fisheries Center Narragansett Laboratory, National 

 Marine Fisheries Serivce, NOAA, Narragansett, RI 02882. 



'Northeast Fisheries Center Sandy Hook Laboratory, National 

 Marine Fisheries Service, NOAA, Highlands, NJ 07732. 



METHODS 



Adult fish captured by trawl in Narragansett Bay, 

 R.I., were held in a 58 m 1 aquarium until they spawned 

 naturally. Fertilized eggs were collected from the 

 aquarium with plankton nets and incubated in 40 1 

 aquaria at 18° and 21C in 3 l%o salinity. Thepostin- 

 cubation series for this study was reared at 18°C. 

 After hatching, the larvae and juveniles were fed 

 zooplankton and brine shrimp nauplii. Larvae were 

 removed regularly for our studies and preserved in 

 4% buffered Formalin 4 and Formalin with Ionol 

 added as a color preservative. Specimens up to 19.5 

 mm standard length (SL) are included in this descrip- 

 tion, but scup were reared to >40 mm in some of our 

 experiments. Eighty-eight larvae from 2.0 to 16.9 

 mm SL were measured with an ocular micrometer. 

 The data were pooled for all fish of the same SL, and 

 all measurements converted into percentages of SL 

 and summarized in Table 1. The following 

 measurements were made: 



Total length (TL) : Tip of snout to end of caudal fin or 

 finfold. 



Standard length (SL): Tip of snout to end of 

 notochord in larvae prior to and during notochord 

 flexure; tip of snout to base of hypural plate once it 

 is formed. All references to length or size in the text 

 refer to SL unless otherwise noted. 



Postanal length: Anus to end of notochord mea- 

 sured along midline of body. 



Manuscript accepted June 1983. 



FISHERY BULLETIN: VOL. 82, NO. 1. 1984. 



4 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



77 



