Abstract. — Most red drum, 

 Sciaenops ocellatus, age and growth 

 research has utilized sagittal 

 otoliths. We evaluated the other 

 otoliths, the lapilli and asterisci, as 

 well as the sagittae, as ageing 

 structures and length-at-age esti- 

 mators in hatchery-reared and wild 

 juveniles (<50 mm SL). Our otolith 

 mounting and sectioning protocol 

 for preparing sagittal sections re- 

 quired significantly less processing 

 time with no loss in accuracy than 

 the more traditional transverse 

 sectioning reported in the litera- 

 ture. Increments in asterisci were 

 clearly visible from the primordium 

 to the otolith margin, whereas the 

 nuclear region of sagittae and 

 lapilli were more opaque and pre- 

 vented detection of all rings. 

 Asterisci were not present at hatch- 

 ing, but on average form six days 

 later, therefore the addition of a 

 constant (6 days) to the ring counts 

 of asterisci resulted in this otolith 

 providing more accurate ages than 

 sagittae or lapilli. According to co- 

 efficients of determination (r 2 ) gen- 

 erated from the relation between 

 fish length and otolith diameter, 

 the sagitta, asteriscus, and lapillus 

 predict fish length in descending 

 order. However, because inner 

 rings on sagittae were usually un- 

 detectable, lengths at ages cannot 

 accurately be predicted. All rings 

 are observable in the asteriscus; 

 thus, by using the 6-day adjust- 

 ment factor accurate length-at-age 

 prediction is possible. 



Differences between the sagitta, 

 lapillus, and asteriscus in 

 estimating age and growth in 

 juvenile red drum, 

 Sciaenops ocellatus 



Andrew W. David 

 J. Jeffery Isely* 

 Churchill B. Grimes 



Panama City Laboratory, Southeast Fisheries Science Center, 



National Marine Fisheries Service, NOAA 



3500 Delwood Beach Road, Panama City, Florida 32408 



The red drum, Sciaenops ocellatus, 

 is a recreationally and commercially 

 important marine fish ranging 

 throughout the Gulf of Mexico and 

 along the Atlantic seaboard to Mas- 

 sachusetts. An estuarine-dependent 

 species, red drum spawn offshore, 

 and juveniles move to estuarine nur- 

 sery areas. After reaching sexual 

 maturity at about age 5 (Mercer, 

 1984), these fish migrate offshore, 

 where they aggregate into large 

 schools. Concern for the declining 

 status of the resource has prompted 

 many Gulf of Mexico and Atlantic 

 states to implement research to pro- 

 vide a sound scientific basis for 

 management. This research in- 

 cludes aspects of early life history 

 important to recruitment processes 

 (Holt et al., 1983), age and growth 

 (Peters and McMichael, 1987; 

 Comyns et al., 1989), artificial pro- 

 pagation (Arnold, 1988), behavior 

 (Fuiman and Ottey, 1993), and 

 spawning stock abundance (Comyns 

 etal., 1991). 



An overwhelming percentage of 

 age and growth investigations have 

 utilized the sagittae because they 

 are the largest of the three otoliths 



and therefore the easiest to extract 

 and examine (Irie, 1960; Campana 

 and Neilson, 1985). Since Panella 

 ( 1971 ) first identified daily growth 

 increments in sagittal otoliths, the 

 formation of daily rings has been 

 confirmed in many species (Jones, 

 1986). 



References to the lapillus are un- 

 common in the literature. Bailey 

 and Stehr ( 1988) reported use of the 

 lapillus to age larval walleye pol- 

 lock, Theragra chalcogramma (Pal- 

 las), younger than 20 days because 

 it was larger than the sagitta up to 

 that age. Brothers and McFarland 

 (1981) used lapilli to age juvenile 

 French grunts, Haemulon flavo- 

 Hneatum . References to the use of the 

 asteriscus in ageing are unknown. 



Previous ages for red drum lar- 

 vae (Comyns et al., 1989) and juve- 

 niles (Peters and McMichael, 1987) 

 were derived from sagittae. Peters 

 and McMichael (1987) found that 

 the inner ring structure was usu- 

 ally unclear in juveniles. They used 

 ten larval otoliths to measure the 

 distance from the primordium to the 

 tenth ring, then began juvenile ring 

 counts with the eleventh ring, 56 um 



Manuscript accepted 22 December 1993. 

 Fishery Bulletin 92:509-515 ( 1994). 



Present Address: U.S. Fish and Wildlife Service, South Carolina Cooperative Fish and 

 Wildlife Research Unit, G-08 Lehotsky Hall, Clemson University, Box 340362, Clemson, 

 South Carolina 29634. 



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