212 



Fishery Bulletin 101(2) 



Ifish lJ invertebrates 



c 100 



0) 



80 



60 



40 



20 



OH 



B 



n = 667 



i 



1 — I — I — |— -I— ■,— .,— .| 



I 



1 



I 



1 



10 20 30 40 50 60 70 80 90 100 110 120 130 140>150 



Fork length (mm) 



Figure 10 



Ontogenetic changes in diet of YOY bluefish based on percent fre- 

 quency of occurrence of fish and invertebrate prey for individuals 

 collected on ocean beaches in northern (A) and southern (B) New 

 Jersey and on estuarine beaches (C) in southern New Jersey during 

 summer and fall 1998. See Figure 1 for location of beaches. 



the ocean also occurred for another species, Menticirrhtis 

 saxatilis, during the same period with exactly the same tag 

 and recapture techniques (Miller et al., 2002). 



Growth 



Earlier estimates for the same and other estuarine systems 

 indicated an average growth rate of 0.9-2.1 mm/day for 

 YOY bluefish (McBride and Conover,1991; McBride et al, 

 1995; Juanes et al., 1993, 1996). Another species, Menticir- 

 rhus saxatilis. that occurred in the same estuarine habitat, 

 had slightly higher growth rates (Mean 1.8 mm/day, range 

 0.7-2.8 mm/day) (Miller et al., 2002). These estimates of 

 growth for bluefish average greater than that for YOY of 

 most other estuarine fish, at least in the Middle Atlantic 

 Bight, where most nonresident, i.e. the fastest-growing spe- 

 cies, range from 0.3 to 1.1 mm/day (Able and Fahay, 1998). 



Food habits 



Just as an understanding of YOY bluefish distribution and 

 abundance in the New York Bight has been largely based 



on estuarine collections, so has the knowledge of their food 

 habits. The ontogenetic shift reported in the diet of YOY 

 bluefish during the transition from pelagic juveniles in the 

 ocean to larger juveniles in estuarine habitats (Marks and 

 Conover, 1993) also occurs on ocean beaches. Observations 

 on northern and southern New Jersey beaches indicate 

 that this transition, from invertebrates to fishes, occurs at 

 approximately the same sizes (80-100 mm FL) as reported 

 elsewhere (Marks and Conover, 1993; Juanes and Conover, 

 1994a, 1994b; Creaser and Perkins, 1994). 



The diet of YOY bluefish in the coastal ocean is similar to 

 that reported elsewhere in the world. The selection of en- 

 graulids and atherinids, as occurs on New Jersey beaches, 

 is similar to that for other populations (Juanes et al., 1996), 

 except that atherinids made up a much smaller percentage 

 of the diet (Table 2). This difference is not easily explained 

 because atherinids are a large component of the surf zone 

 fish assemblage on New Jersey beaches during the summer 

 and fall (Rowe and Able, unpubl. data). 



In summary, ocean beaches and deeper waters of the in- 

 ner continental shelf are used continuously by YOY blue- 

 fish from summer through the fall migration. Bluefish in 



