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Fishery Bulletin 101(2) 



although the two are intimately related (Werner and Gil- 

 liam, 1984). Selecting for optimized growth, however, ap- 

 pears not to be an issue for these two estuarine generalists. 

 If upstream PNAs are better nurseries (i.e. provide better 

 conditions for survival and perhaps growth), delayed PNA 

 recruitment (longer estuarine migrations), especially for 

 Atlantic croaker, may maximize ultimate fitness (Miller 

 et al., 1985; Shapiro, 1987). Factors affecting transport of 

 young to upstream areas may, therefore, be an important 

 determinant of population fitness. 



Unexpected patterns of recruitment into middle region 

 creeks suggested that their function or recruitment po- 

 tential as fish nursery areas may difTer significantly from 

 other regions. Even though these creeks were physically 

 similar to creeks on either end of the estuarine transects, 

 lower abundances of spot and Atlantic croaker in middle 



areas suggested that they either avoided (bypassed) middle 

 areas or endured higher initial mortalities there. Higher 

 initial mortality in middle regions seems unlikely because 

 catches were generally low throughout the sampling pe- 

 riod. Relatively poor habitat quality could explain the low 

 densities of fishes in these creeks. This hypothesis was sup- 

 ported by the fact that most fishes settling in middle re- 

 gions of both systems exhibited significantly smaller mean 

 lengths and were lighter per length. The same pattern was 

 observed for Atlantic menhaden in these systems (Ross, 

 1992). Szedlmeyer (1991) also found lower abundances 

 and species richness in middle reaches of a Florida estuary 

 and suggested that either less diverse habitat or greater 

 salinity variation (or both) influenced this result. Ross 

 and Kpperly (1985) found stations close to the periphery 

 of Pamlico Sound (including the middle area of this study) 



