NYMAN and CONOVER: YOUNG-OF-THE-YEAR BLUEFISH 



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c: 



CD 



Z) 



cr 



QJ 



o 



u 



d 



CD 

 Z) 

 O" 

 QJ 



30 



20 



10 







60 



50 - 



40 - 



30 - 



20 - 



10 - 







150 



180 



Julian Date of First Ring Deposition 



Figure 10. — Estimated date of first ring deposition for all YOY bluefish caught in Great 

 South Bay in 1985 (n = 561) and in 1986 {n = 868) using the respective age-length equa- 

 tions in Fig. 9. 



ture. Feeding periodicity was probably the pri- 

 mary artifact of confinement that could have af- 

 fected the rate of ring production in caged fish. 

 However, Marshall and Parker (1982) showed 

 that feeding periodicity did not significantly af- 

 fect ring production in sockeye salmon, 

 Oncorhynchus nerka. 



We were unable to determine directly the num- 

 ber of days between spawning and first ring depo- 

 sition because numerous attempts to capture 

 running-ripe females for initiating experiments 



on eggs and larvae were unsuccessful. However, 

 most species of fish deposit the first daily growth 

 increment within a few days of hatching (Broth- 

 ers et al. 1976; Radtke and Dean 1982; McGurk 

 1984; Radtke 1984; Davis et al. 1985). Recent ev- 

 idence suggests this is also true in bluefish. Lar- 

 vae captured off Long Island in 1987 had about 

 seven otolith increments at a total body length of 

 4-5 mm (R. K. Cowen and D. O. Conover, unpubl. 

 data). Based on the rate of development at 20°C in 

 the laboratory observed by Deuel et al. (1966), 



247 



