FISHERY BULLETIN: VOL. 74, NO. 2 



Important spawning and nursery areas probably 

 extend farthest downstream when the run is 

 large and spawning is successful. The upper Del- 

 aware area near Hancock is probably the core 

 around which expansion and contraction occurs. 

 Downstream sections of the nursery usually 

 contribute little or nothing to production of adults 

 even if the nursery expands. Since 1925, larger 

 shad runs in the Delaware River have depended 

 upon one year class which successfully passed the 

 Philadelphia area (Chittenden 1975). Down- 

 stream nurseries contribute to production only 

 when water quality near Philadelphia per- 

 mits shad passage earlier than normal; there is 

 usually catastrophic destruction of the young as 

 they pass Philadelphia (Chittenden 1969). There- 

 fore, in general, it appears that nursery and 

 spawning areas contribute to production in pro- 

 portion to their distance from Philadelphia. Only 

 a small part of the historical nursery area now 

 contributes to production of adults. 



Future Prospects 



Future prospects of shad in the Delware River 

 depend primarily upon water quality in the tidal 

 area and upon a dam near Tocks Island (Chitten- 

 den 1969). The present remnant runs appear 

 based upon stocks that spawn far upstream in a 

 small part of their former spawning grounds and 

 whose progeny pass tidal water in late fall when 

 dissolved oxygen increases. A greater area would 

 contribute to successful production if dissolved 

 oxygen increased earlier, because fish spawned 

 farthest downstream pass tidal water first. There- 

 fore, the magnitude of future runs will reflect dis- 

 solved oxygen conditions, because the area con- 

 tributing to production will change accordingly. If 

 recent or typical water quality was maintained, 

 future runs would usually be small. Fortuitous 

 circumstances would occasionally produce larger 

 runs as in the early 1960's. 



Construction of a dam near Tocks Island would 

 greatly affect shad. They probably would be ex- 

 tirpated from the Delaware if successful fishways 

 for both adults and young are not provided and 

 water quality in the tidal area is unchanged. Cold 

 water reservoir releases drastically and ad- 

 versely affect usage of downstream spawning and 

 nursery areas, if only due to avoidance (Chitten- 

 den 1972). Cold water releases from a Tocks Is- 

 land dam would shift spawning and nursery 

 areas far downstream, and spawning grounds 



under any water release circumstances would be 

 downstream of the area that presently produces 

 adults successfully. Therefore, the young pro- 

 duced would reach tidal water too early to pass 

 seaward successfully. Great water quality im- 

 provement would be needed in the tidal area just 

 to maintain the present small runs. Water qual- 

 ity improvement by flow augmentation might be 

 self-defeating, because the young now move 

 downstream even during the summer; and in- 

 creased discharge and temperature decrease 

 would accelerate this. The potential would be 

 brighter if successful fishways were provided. The 

 reservoir might be an excellent nursery for the 

 young judging from their pelagic habits, their 

 preference for pool habitats, and the former im- 

 portance of tidal nurseries. This, combined with 

 nurseries upstream from the reservoir, might es- 

 tablish larger runs — if the young passed the dam 

 and tidal water successfully. However, much 

 larger runs would be achieved with less risk at 

 possibly less cost if Delaware River water quality 

 in the tidal area were restored and the dam was 

 not built. Then, the outstanding recreational po- 

 tential of a clean tidal area in a great population 

 center would be restored — and the outstanding 

 recreational opportunity of an unobstructed Del- 

 aware River would not be lost. 



ACKNOWLEDGMENTS 



For assisting in collections, I am deeply grate- 

 ful to J. Westman and J. Hoff, J. Harakal, D. Rie- 

 mer, J. Barker, F. Bolton, R. Coluntuno, K. 

 Compton, R. Gross, C. Masser, R. Stewart, J. 

 Miletich, S. Hoyt, L. Schulman, H. Dinje, H. Buck- 

 ley, J. Musick, M. Bender, J. Gift, C. Townsend, 

 R. Bogaczk, and K. Marcellus of or formerly of 

 Rutgers University, Harvard University, the New 

 Jersey Division of Fish and Game and/or the New 

 York Department of Environmental Conservation. 



Fred and William Lewis, Jr. generously gave 

 permission to collect at their fishery at Lam- 

 bertville and frequently assisted in seining. W. 

 Kelly of the New York Department of Environ- 

 mental Conservation and J. Musick, then at Har- 

 vard University, provided observations. J. 

 McEachran and R. Noble of Texas A&M Univer- 

 sity reviewed the manuscript. 



The U.S. Bureau of Sport Fisheries and 

 Wildlife, New Jersey Division of Fish and Game, 

 Pennsylvania Fish Commission, and New York 

 Department of Environmental Conservation 



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