390 



Fishery Bulletin 91(2). 1993 



Table 1 



Sources of bluefish Pomatomus saltatrix samples examined in this study. Size range is given as mmFL. Larger datasets (n>500) were 

 used to compile length-frequency distributions, and some fish from 1987-88 were used for otolith analyses. Other samples ln<13) were 

 obtained specifically for otolith analyses. 



Most data and specimens supplied by the N.C. Dep. Mar. Fish. (NCDMF); additional material from S.C. Wildl. Mar. Resour. Dep. 

 (SCWMRD), Univ. South Carolina (USC) Belle Baruch Lab., and the Southeast Area Monitoring and Assessment Program (SEAMAP). 

 Data from these sources were truncated at 360mm FL. 



Mean ring count (= daily age) was subtracted from 

 date of capture to estimate birthdate, assuming no lag 

 between birthdate and date of first ring deposition. 

 Average growth rate was calculated as ([FL-2mm]/daily 

 age); a 2mm constant represents the size-at-hatching 

 (Deuel et al. 1966). Growth rate was also calculated 

 using least-squares regression of FL on daily age. 



Results 



Evidence of spring-spawned juveniles Small blue- 

 fish (21-60mmFL) entered North Carolina estuaries 

 in March and April (Fig. 1A). These fish were similar 

 in size to spring-spawned bluefish collected by neus- 

 ton nets on incoming tides at Breech Inlet (South Caro- 

 lina) as early as 29 April 1988, and as late as 16 June 

 1988 (Table 2). 



This spring-spawned cohort grew rapidly and re- 

 cruited to the North Carolina pound-net fishery in July 

 (Fig. IB). These fish became progressively larger until 

 the fishery ended in October. A July recruitment of 



spring-spawned fish was also evident in SEAMAP 

 trawling (Fig. 1C). 



Bluefish <175mmFL in July were YOY that had been 

 spawned primarily in April (Table 2, Fig. 2). For ex- 

 ample, a sample from 29 July 1987 had a mean 

 birthdate of 19 April ± 13d (±1SD), and a sample for 

 26 July 1988 had a mean birthdate of 26 April ± 12d 

 (Table 2). Bluefish observed in July, but >200mmFL, 

 showed evidence of an overwinter growth mark on their 

 otoliths. Very few specimens of 175-200mm were avail- 

 able for otolith analysis, which precluded a more 

 precise separation of age from size modes. Bluefish 

 juveniles were larger and older in August samples 

 (Table 2). Spring-spawned YOY bluefish grew 1.2- 

 1.9mm/d during this time-period (Fig. 3). 



Evidence of summer-spawned juveniles Small blue- 

 fish (<150-170mmFL) appeared in North Carolina es- 

 tuaries and in nearshore continental shelf waters of 

 the SAB in October (Fig. 1). Small bluefish (< 150mm) 

 collected near Bogue and Stono Inlets in October and 

 November 1988 had a mid-July birthdate (Table 2, 



