Ross: Relative value of different estuarine nursery areas for luvenile marine fishes in North Carolina 



391 



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18Mar 

 n=544 



1 Apr 



n.ll05 



15 Apr 



n-3515 



29ADr 

 n=1337 



CAPE FEAR ESTUARY 



MIDDLE 



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n=2 



13May 

 n=1052 



27May 

 n=1734 





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n=520 



n=230 



n=253 



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n=1938 



n=2705 



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n = 250 



n=424 



• n=2012 



10 20 30 40 50 60 10 20 30 40 50 60 10 20 30 40 50 60 



Standard length (mm) 



Figure 5 



Spot length frequencies in general areas of the Cape Fear, NC. estuary by sampling week, March-June 1987. Solid dots represent 

 mean SL. 



area creeks (Figs. 3 and 5). Initial recruitment was high 

 in the lower Cape Fear area, whereas it lagged behind in 

 the middle and upper areas (Fig. 3). Nevertheless, all Cape 

 Fear areas reached peak numbers by the second or third 

 sampling dates (Fig. 3). 



Size distributions The bulk of the spot year class recruited 

 to all creeks from mid-March to early April; however, some 

 small fish (<25 mm) continued to enter the creeks through 

 the end of May (Figs. 4 and 5). The smallest spot captured 

 in both systems were always between 13 and 15 mm SL 

 (Figs. 4 and 5). Because the trawl can collect spot and 

 Atlantic croaker at least to 10 mm SL , 13-15 mm prob- 

 ably represented the smallest recruitment sizes of spot to 

 nursery habitats. 



Differences in mean spot SLs between areas steadily in- 

 creased during the study from <1 mm (through mid- April) 

 to 4.3 mm in the Cape Fear and from 1 to 6.2 mm in the 



Pamlico. Although mean spot SLs exhibited the small- 

 est variations between areas in the Cape Fear system 

 (Fig. 5), they were significantly different (paired ^tests, 

 P<0.05) between areas on most sampling dates. No area 

 in the Cape Fear had consistently larger or smaller mean 

 spot SLs. After mid-April mean SLs of spot from all four 

 Pamlico areas were larger than those from the Cape Fear. 

 Within the Pamlico system (Fig. 4) spot in the mid-lower 

 area had significantly larger (P<0.05) mean SL (except 

 sampling weeks four and six), and fish in the middle area 

 were always significantly smaller (P<0.05) than those in 

 the other three areas. 



Growth Estimated spot ages ranged from 61 to 157 days 

 (17-35 mm SL, /!=379). All of the age-SL relationships 

 used to assess growth rates (Fig. 6) were highly significant 

 (P<0.0001). Regression residuals were evenly distributed 

 around zero, indicating that the exponential growth model 



