206 



Fishery Bulletin 101(2) 



400 



200 

 



t^- 



1997 

 A Aug 4 7 " 



'I ' l i V i'i' r i I i S i'i'i'if VfV i iS'i'i'i'i 



1998 



Aug. 3 - 4 

 n = 5 



1 4 7 10 13 16 19 22 25 28 

 Oct. 15-17 

 n = 599/ 



i V i 1 1 



7 10 13 16 19 22 25 28 



Sampling station 



Figure 4 



Spatial variation in abundance (CPUE) of young-of-year bluefish by sampling period on north- 

 em New Jersey beaches by collection date during 1997 and 1998. See Figure 1 for sampling 

 locations. 



recaptured individuals ranged from 0.1 to 2.2 mm FlVday 

 with a mean value of 1.4 mm FLVday across all habitats 

 (Fig. 9). The differences between years in the estuary and 

 between the estuary and the ocean were not significantly 

 different. Growth rates, in length, did decline slightly over 

 the summer with the highest individual growth occurring 

 in July and August and lower values in late August or 

 September through October regardless of how the growth 

 is expressed (Fig. 9). 



Food habits 



Fish dominated the stomach contents of YOY bluefish from 

 ocean beaches in northern and southern New Jersey and in 

 the estuary, occurring in more than GO'^/t of the stomachs in 

 both areas (Table 2). Prey fish species in the ocean included 

 bay anchovy iAnchoa mitchilli, 21.69c and 24.T'A frequency 

 of occurrence on northern and southern beaches, respec- 

 tively), silversides (Menidia spp., <2'7, ), northern kingfish 

 iMenticirrhuK saxatilis. <0.5'; ), and northern pipefish ^Syll■ 

 gnathus fuKcus. <0.2'/i ), with about 40'; of the fish in both 

 areas unidentified. Evidence of cannibalism was rare, with 

 only 2.3% (northern) and 0.3% (southern) incidence. Other 

 important prey categories (>10''r frequency of occurrence) 

 included gammarid amphipods and a variety of decapod 



crustaceans. The occurrence of empty stomachs was infre- 

 quent. In the estuary, stomach contents were somewhat dif- 

 ferent: the dominant prey fish species consisted of Menidia 

 spp. (22.0% frequency of occurrence), smaller numbers of 

 Fundulus majalis less frequently (5.1%), and a large pro- 

 portion of unidentified fish (55.9%). AncTioo spp. were nota- 

 ble by their absence in relation to diets in the ocean. Other 

 important categories included decapod crustaceans, which 

 were mostly unidentified shrimp. Empty stomachs repre- 

 sented 18% of the total examined, as a result of this and the 

 relatively small number examined, the effective sample size 

 was much smaller than those from ocean beaches. 



The relative contribution of fish and invertebrates in the 

 diet changed with size and to some degree location (Fig. 

 10). Fish from the ocean beaches were consumed by virtu- 

 ally all size classes of YOY bluefish, including some of the 

 smallest individuals in our collections (<40 mm FL), but fish 

 occurrence in the diet became more frequent beginning at 

 sizes of approximately 80-100 mm FL, depending on area. 

 In northern New Jersey beaches, invertebrates dominated 

 the diet at sizes of 30->70 mm FL, whereas fish occurred in 

 >70% of stomachs at sizes >80 mm FL, which increased to 

 >80% in sizes >90 mm FL. In southern New Jersey beaches, 

 where smaller bluefish (<50 mm FL) were not captured, in- 

 vertebrates dominated the diets of bluefish up to 80-90 mm. 



