Recruitment of bluefish Pomatomus 

 saltatrix to estuaries of the U.S. 

 South Atlantic Bight* 



Richard S. McBride 



Rutgers University Marine Field Station 

 Institute of Marine and Coastal Sciences 

 PO Box 278, Tuckerton. New Jersey 08087 



Jeffrey L. Ross 



North Carolina Division of Marine Fisheries 

 PO Box I 550. Manteo, North Carolina 27954 



David O. Conover 



Marine Sciences Research Center 



State University of New York 



Stony Brook. New York 1 I 794-5000 



The bluefish Pomatomus saltatrix 

 is a pelagic species that is distrib- 

 uted circumtropically (Briggs 1960, 

 Richards 1965, van der Elst 1976, 

 Fable et al. 1981, Pollock 1984, 

 Lenanton & Potter 1987). Ichthyo- 

 plankton surveys off the U.S. east 

 coast indicate three separate spawn- 

 ing concentrations of bluefish, 

 namely (Da spring-spawned cohort 

 produced between March and May 

 in the South Atlantic Bight (SAB), 

 (2) a summer-spawned cohort origi- 

 nating between June and August in 

 the Middle Atlantic Bight (MAB), 

 and (3) a fall-spawned cohort pro- 

 duced in the SAB between Septem- 

 ber and January (Norcross et al. 

 1974, Kendall & Walford 1979, 

 Powles 1981, Collins & Stender 

 1987). 



The abundance of bluefish has 

 fluctuated widely along the Atlan- 

 tic coast during the past century 

 (Baird 1873, Bigelow & Schroeder 

 1953). Recently, population abun- 

 dance increased steadily from the 

 early 1960s to the late 1970s 

 (Gilmore 1985) and remained rela- 

 tively high during the 1980s (NMFS 

 1987, 1988). Chiarella & Conover 

 (1990) speculated that increased 

 recruitment success of the spring- 

 spawned cohort is largely respon- 



sible for this recent increase in 

 overall bluefish abundance. They 

 demonstrated that bluefish off the 

 New York coast during the 1980s 

 were primarily spring-spawned fish, 

 and this contrasts with a more 

 equal proportion of spring-spawned 

 and summer-spawned fish observed 

 by Lassiter ( 1962) in the late 1950s, 

 when overall bluefish abundance 

 was lower. 



Our understanding of how these 

 three intra-annual cohorts contrib- 

 ute to the overall year-class 

 strength of bluefish along the U.S. 

 Atlantic coast, however, is still un- 

 clear. For example, Kendall & 

 Walford (1979) hypothesized that 

 spring-spawned bluefish were trans- 

 ported from the SAB northward into 

 the MAB estuaries, but Collins & 

 Stender (1987) postulated that 

 spring-spawned fish were trans- 

 ported directly inshore to estuaries 

 of the SAB. Otolith analyses of 

 young recruits have confirmed the 

 northerly dispersal of spring- 

 spawned fish as proposed by 

 Kendall & Walford (Nyman & 

 Conover 1988, McBride & Conover 

 1991), but similar studies of recruit- 

 ment to SAB estuaries are nonex- 

 istent. Length-frequency data for 

 bluefish from SAB estuaries is also 



sparse, thus it has been difficult to 

 evaluate if bluefish use estuaries in 

 the SAB as nursery grounds. Here 

 we present evidence of recruitment 

 by three cohorts of young-of-the- 

 year (YOY) bluefish to estuaries and 

 nearshore habitats of the SAB. 



Materials and methods 



Field sampling 



Bluefish <360mm fork length (FL) 

 were collected from estuarine pound- 

 net (a summer fishery) and oceanic 

 trawl (a winter fishery) samples 

 taken in North Carolina (Table 1). 

 The upper limit of 360mmFL repre- 

 sents the largest size attained by 

 young bluefish in their first year of 

 life (Lassiter 1962). Additional data 

 were also obtained from a variety of 

 fishery-independent sources of sam- 

 pling from North Carolina to Florida 

 (Table 1). 



Otolith aging 



To avoid dissolution, sagittal otoliths 

 were extracted directly in the field, 

 or from frozen or preserved (95% 

 ETOH) fish. Nyman & Conover 

 (1988) validated that daily incre- 

 ments are present in otolith micro- 

 structure, and we followed their 

 methods of preparation. Sagittae 

 were chosen randomly from YOY 

 specimens of the large fishery col- 

 lections. Eight of the total 51 sagittae 

 prepared were determined to be 

 yearling fish and were excluded from 

 further analysis. Daily sagittal in- 

 crements were counted indepen- 

 dently three times, and a mean 

 count was considered valid if the 

 range was <10% of the mean count. 

 If the range was greater (11% of the 

 time ), then a fourth count was made 

 and the outlier was discarded. 



Manuscript accepted 22 January 1993. 

 Fishery Bulletin, U.S. 91:389-395 (19931 



* Contribution 867 of the Marine Sciences 

 Research Center, State University of New 

 York at Stony Brook. 



389 



