Able et al : Use of ocean and estuarine habitats by young-of-the-year Pomatomus saltatrix 



205 



Sampling week 



Figure 3 



Abundance (CPUEl of young-of-year bluefish on northern 

 New Jersey ocean beaches during 1995-98 and southern 

 New Jersey ocean beaches and estuarine beaches during 

 1998. See Figure 1 for sampling locations. 



larger mode in October approximated the size of the larger 

 mode in October 1995, and the smaller mode resembled 

 that of the intermediate mode during the same month. In 

 September 1997 there was a single size mode, and perhaps 

 two in October, and the latter were similar in size to the 

 largest and intermediate modes in 1995. In 1998 the YOY 

 were represented by a small size mode similar to that in 

 August 1995 and the dominant size class in October was 

 similar to the intermediate group in October 1995; thus 

 the larger mode, that was present in other years was not 

 present in 1998. Over the same time period, there appeared 

 to be some relationship between distance offshore, depth, 

 and size (Fig. 5). When fish occurred in the deepest strata 

 sampled they were often the largest individuals and this 

 was especially evident in 1995 and 1996. 



Young-of-year on northern New Jersey beaches had simi- 

 lar mean sizes but fewer large and small fish than in inner 

 continental shelf collections (Fig. 6). Often two modes were 

 represented but these did not occur consistently in all col- 

 lections. In early fall one mode often consisted of very small 

 fish (<4-7 cm FL). This was obvious in early October 1995, 

 September and October 1996, October 1997 and 28 Septem- 

 ber-! October 1998. Large fish (>17 cm FL) were also repre- 

 sented in the fall, especially in October 1995 and 1998. 



The average size of YOY on ocean beaches in southern 

 New Jersey in 1998 was similar to those collected on the 

 inner continental shelf, on northern New Jersey beaches, 

 and in the estuary (Fig. 7). In most instances a single mode 

 was evident, with the exception of October when few larger 

 fish were present. 



(Fig. 3). Peaks occurred much later in October in relation 

 to northern beaches in all years and, compared to the es- 

 tuary, relative abundance was much higher than in the 

 adjacent estuary during the entire sampling period, with 

 peak abundance reaching approximately 400 individuals/ 

 tow (in the estuary only 6 individuals/tow were collected). 

 Both ocean and estuarine beaches had very small numbers 

 in late June and July, and abundance peaks in August and 

 early September. Although estuarine catches declined by 

 late September, with zero catches continuing through the 

 end of the sampling period, catches on ocean beaches were 

 highest in late September and early October and did not 

 decline until October or early November. 



Size composition 



Young-of-year bluefish were represented by different size 

 classes or cohorts and these varied between years and loca- 

 tions (Figs. 5-7). The size at first occurrence in the ocean 

 was as small as approximately 20 mm FL in some years 

 and around 50 mm FL in other years. Largest YOY were 

 collected in otter trawl collections on the inner continental 

 shelf where individuals >19 cm were common (Fig. 5). In 

 1995 several size classes were evident in August and three 

 in October; the largest, in the latter, was approximately 17- 

 26 cm FL, the smallest was 6-9 cm FL, and an intermediate 

 group was 10-16 cm FL( Fig. 5). In 1996.only one size class 

 was represented in August and only two in October. The 



Residency and movements 



The results from the tag and recapture experiments dif- 

 fered markedly between the estuary and the ocean and 

 in no instance were fish from the estuary or the ocean 

 captured in the other area (Fig. 8). Of the fish tagged in 

 the ocean during 1999 («=4987, 50-202 mm FL) only two 

 (0.04'7f ) were recaptured, whereas in 2000 (n=649, 55-241 

 mm FL) none were recaptured. The number of tag returns 

 was much higher in the estuary during 1999 (?!=856, 59- 

 250 mm FL ) with 29 (3.4%) recaptured; whereas in 2000 

 (;?=661, 55-244 mm FL) only five (0.8%) were recaptured. 

 In the ocean, the two fish recaptured were both at liberty 

 for 15 days. In fact, they were tagged on the same day at 

 the same location and recaptured together on the same day 

 and at the same location, suggesting that they were travel- 

 ing together. Over that period they traveled a minimum of 

 17 km from the tagging location at Surf City south to the 

 recapture location at Holgate (Fig. 1). In the estuary the 

 number of days at liberty ranged from 2 to 18 days in 1999 

 and 5-27 days in 2000 (Fig. 8). All of the fish tagged in the 

 estuary at Graveling Point in both years were captured 

 at the same location, indicating a much higher period of 

 residency than could be demonstrated in the ocean. 



Growth 



Maximum growth rates for bluefish are among the highest 

 recorded for the YOY of any fish species. Values for tagged and 



