758 



AbStrSCt.— After spending summer 

 months in estuaries, spring- and sum- 

 mer-spawned young-of-the-year (YOY) 

 bluefish, Pomatomus saltatrix. migrate 

 out to continental shelf waters of the 

 Mid-Atlantic Bight in early autumn. 

 Adult bluefish are found on the conti- 

 nental shelf throughout summer and 

 fall. Both juveniles and adults have high 

 food consumption rates and are gener- 

 ally piscivorous. To determine princi- 

 pal prey types on the shelf, dietary 

 analyses were performed on YOY and 

 adult bluefish collected from National 

 Marine Fisheries Service autumn bot- 

 tom trawl surveys in 1994 and 199.5. 

 Both spring- and summer-spawned 

 YOY bluefish diets were dominated by 

 bay anchovy. However, the significantly 

 larger size of the spring-spawned cohort 

 was associated with the consumption 

 of other prey species such as squid, 

 butterfish. striped anchovy, and round 

 herring. Summer-spawned bluefish 

 were significantly smaller in 199.5 than 

 in 1994; diet and prey size comparisons 

 suggest that body size had a dramatic 

 influence on the amount of piscivorous 

 feeding in the summer-spawned cohort. 

 Adult bluefish diet was dominated by 

 schooling species such as squid, butter- 

 fish, and clupeids. Cannibalism was 

 virtually nonexistent. Daily ration es- 

 timates of YOY bluefish on the shelf (4- 

 12"^? body wt/d i were similar to estua- 

 rine estimates in late summer It is es- 

 timated that during the month of Sep- 

 tember, YOY bluefish in aggregate con- 

 sumed 6.0 to 6.8 billion bay anchovies 

 in 1994 and from 2.2 to 5.3 billion in 

 1995. The effect of this predatory loss 

 on population dynamics of bay anchovy 

 and the fish community on the conti- 

 nental shelf is unknown. 



Foraging habits of bluefish, 

 Pomatomus saltatrix, on the 

 U.S. east coast continental shelf* 



Jeffrey A. Buckel 



Marine Sciences Research Center 



State University of New York 



Stony Brook, New York 11794-5000 



Present address James J Howard Manne Sciences Laboratory 

 National Marine Fishenes Service, NOAA 

 74 Magruder Road 

 Highlands, New Jersey 07732 



Email address ibuckelgsh nmfsgov 



Michael J. Fogarty 



Northeast Fisheries Science Center 

 National Manne Fisheries Service, NOAA 

 166 Water Street 

 Woods Hole, Massachusetts 02543 



David O. Conover 



Marine Sciences Research Center 

 State University of New York 

 Stony Brook, New York 11794-5000 



Manuscript accepted 1 December 1998. 

 Fish. Bull. 97:758-775(1999). 



One of the dominant marine pisci- 

 vores along the U.S. east coast is the 

 bluefish, Pomatomus saltatrix 

 (Juanes et al., 1996). Bluefish 

 spawned in offshore waters of the 

 South Atlantic Bight in the spring 

 (spring-spawned ) are advected north- 

 ward in waters associated with the 

 Gulf Stream (Hare and Cowen, 1996) 

 and move into mid-Atlantic Bight 

 estuaries in June at -60 mm fork 

 length (Kendall and Walford, 1979; 

 Nyman and Conover, 1988; McBride 

 and Conover, 1991). A second wave 

 of recruits consisting of summer- 

 spawned fish occur in nearshore wa- 

 ters from mid to late summer. 



In estuaries, bluefish exhibit 

 rapid growth rates that are fueled 

 by high food consumption and 

 evacuation rates (Juanes and Con- 

 over, 1994; Buckel et al., 1995; Buckel 

 and Conover, 1996). In the Hudson 

 River estuary, for example, preda- 

 tion by bluefish is high enough to 

 account for virtually all natural mor- 

 tality of young-of-the-year (YOY) 



striped bass during their summer- 

 fall growing season (Buckel et al., 

 1999). After spending the summer 

 months in estuaries, YOY bluefish 

 migrate back out onto the shelf and 

 migrate southward to overwinter 

 (Munch and Conover, in press). 

 Spring-spawned YOY bluefish mi- 

 grate out of estuaries at a size of 

 -180 mm fork length (FL) and -100 g 

 ( Nyman and Conover, 1988; McBride 

 and Conover 1991). By age 1, these 

 spring-spawned fish attain sizes of 

 -260 mm FL and weights of -300 g 

 (Chiarella and Conover, 1990). 

 Therefore, an individual spring- 

 spawned bluefish gains from 100 to 

 200 g during its autumn migration. 

 Given a 15% gross growth efficiency 

 (Juanes and Conover, 1994; Buckel 

 et al. 1995), a single bluefish could 

 thus consume from -650 to 1300 g 

 of prey 



 Contribution 1134 of the Marine Sciences 

 Research Center, State University of New 

 York, Stony Brook, New York 11794. 



