CHAO and MUSICK: LIFE HISTORY OF JUVENILE SCIAENID FISHES 



upon these species by adaptive morphological 

 limitations rather than to selective feeding per se. 



CONCLUSION 



In the Sciaenidae, a family of primarily coastal 

 marine fishes, many species utilize the same 

 coastal area as common nursery and seasonal 

 feeding grounds. In the York River estuarine sys- 

 tem, the coexistence of sciaenid fishes may be at- 

 tributed to: 1) Differences in their temporal and 

 spatial distributions. Juveniles of the four most 

 abundant sciaenid fishes entered the estuary at 

 different times of the year. Within a given period, 

 the highest catches of each species were usually in 

 different areas (upper and lower reaches) and 

 depths (beach zone, shoals, and channel) of the 

 York River system. Also, the size distributions of 

 each species were often separated temporally and 

 spatially. 2) Differences in their habitat adapta- 

 tions and food habits. The diverse morphological 

 features of these sciaenid fishes enable them to 

 utilize food resources from different levels (micro- 

 habitats) of the water column. Correlations of 

 feeding apparatus, digestive system, and food 

 habits are evident and result in niche division. 3) 

 The abundant food resources of the study area. At 

 times some prey organism (e.g., Neomysis 

 americanus) may be ubiquitous and very abun- 

 dant, providing food for several species of juvenile 

 sciaenids. Then food would not be a limiting re- 

 source and intrafamilial competition may not oc- 

 cur. 



ACKNOWLEDGMENTS 



We thank D. F. Boesch, B. B. Collette, G. C. 

 Grant, P. A. Haefner, Jr., and J. V. Merriner for 

 their helpful suggestions and critical review of 

 this manuscript. We also express our appreciation 

 to the following persons from VIMS: R. Bradley, J. 

 Gilley, and M. Williams for preparation of graphs; 

 Susan Barrick and her staff at the VIMS library; 

 William H. Kriete, Jr., James Colvocoresses, 

 Douglas F. Markle, Jerome E. Illowsky, and 

 James Green who helped in field work, including 

 trawling, collecting, and measuring fishes during 

 the study; Deborah A. Sprinkle and Julia F. Mil- 

 len who typed many drafts of this manuscript; 

 Joyce S. Davis who answered many questions 

 about different surveys; Genie Shaw who re- 

 trieved all the hydrographic data from the VIMS 

 computer data storage; and to our colleagues, K. 



W. Able, J. Colvocoresses, D. F. Markle, J. D. 

 McEachran, L. P. Mercer, G. Sedberry, and C. A. 

 Wenner for allowing us to talk to them about sci- 

 aenids and for helpful suggestions. 



Our special appreciation goes to Bruce B. Col- 

 lette, Systematics Laboratory, National Marine 

 Fisheries Service, NOAA, Washington, D.C., who 

 instigated this joint adventure a few years ago. 



D. E. McAllister, National Museums of Canada, 

 reviewed the final draft of the manuscript and 

 offered helpful suggestions. J. McConnell and her 

 staff at the Word Processing Centre, National 

 Museums of Canada, typed the final draft. 



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