PRESENT AND HISTORICAL SPAWNING GROUNDS AND 

 NURSERIES OF AMERICAN SHAD, ALOSA SAPIDISSIMA, 



IN THE DELAWARE RIVERA 



Mark E. Chittenden, Jr.^ 



ABSTRACT 



Spawning occurs from late May into July but mainly in a 3-wk period from late May to mid-late June. 

 Spawning ends progressively later proceeding upstream. Light intensity seemed to regulate when 

 spawning began each day. Fish selected shallow riffle areas in preference to pool habitat for spawning. 

 Spawning behavior is described. 



Except for the most grossly polluted tidal water, spawning and nursery areas now extend throughout 

 fresh water of the main Delaware and into the East and West branches. The most important spawning 

 grounds and nurseries are now located from Port Jervis, N.Y., to Hancock, N.Y., and extend into the 

 lower East Branch; this has probably been the case since 1910-20. There has been a fundamental 

 upstream shift in the chief spawning grounds and nurseries since the decline of the Delaware River 

 shad runs, because these historically extended downstream from about Delaware Water Gap, Pa., and 

 included tidal water. Reasons for this shift suggest intrastream homing. 



Only a small proportion of the historical nursery now contributes to production. Nursery and 

 spawning areas now contribute to production of adults in proportion to their distance from Philadel- 

 phia, Pa. The extent of the spawning and nursery area since about 1910-20 has probably expanded and 

 contracted around a core area in the upper Delaware near Hancock. Future prospects of Delaware River 

 shad are discussed. They depend upon water quality in the tidal area and the proposed Tocks Island 

 dam. Extirpation of the remnant runs is a distinct possibility. 



The Delaware River basin once supported larger 

 landings of American shad, Alosa sapidissima, 

 than any other river system (Stevenson 1899). 

 Annual landings near the turn of the century av- 

 eraged about 14-17 million pounds but have con- 

 sistently been much less than 0.5 million pounds 

 since 1920 (Sykes and Lehman 1957; Chittenden 

 1974). Gross pollution near Philadelphia, Pa. 

 (Figure 1), has been the chief reason for the low 

 abundance since at least 1920 (Ellis et al. 1947; 

 Sykes and Lehman 1957; Chittenden 1969). If pol- 

 lution were cleared up, shad runs could be largely 

 restored (Chittenden 1969). 



Spawning and nursery areas of shad in the 

 Delaware River are not well known, although the 

 U.S. Army Corps of Engineers proposes to con- 

 struct a dam near Tocks Island, a few kilometers 

 upstream of Delaware Water Gap, Pa. If proposed 

 fishways are not successful, this dam would pre- 

 vent access to nearly half the 406 km of fresh 

 water between Marcus Hook, Pa., and Hancock, 

 N.Y. Sykes and Lehman (1957) concluded that the 



'Based on part of a dissertation submitted in partial fiilfill- 

 ment of the requirements for a Ph .D. degree, Rutgers University, 

 New Brunswick, N.J. 



^Department of Wildlife and Fisheries Sciences, Texas A&M 

 University, College Station, TX 77843. 



chief spawning and nursery areas were located 

 upstream of Tocks Island. Their studies were 

 made in 1950-52 when shad runs were almost 

 nonexistent, however, and their conclusion was 

 necessarily based on extremely limited data. 

 Shad runs markedly resurged during the early 

 mid-1960's when I made extensive collections and 

 observations of adults and young. This paper de- 

 scribes the spawning period, behavior during the 

 spawning period, recent and historical spawning 

 and nursery grounds, and discusses the future 

 prospects of shad in the Delaware River. 



MATERIALS AND METHODS 



Locations referred to are indicated in Figure 1 

 or, when first mentioned, by their approximate 

 distances upstream from Marcus Hook, situated 

 about 90 km downstream from the fall line at 

 Trenton, N.J., and near the transition between 

 fresh and brackish water. 



Adults (278 males and 250 females) were col- 

 lected during the spawning runs at Lambertville, 

 N.J., using a 76-mm stretch-mesh, 107-m long 

 and 3.6-m deep haul seine at 3- or 4-day intervals 

 from 5 April to 19 May 1963, 20 March to 18 May 

 1964, 26 March to 7 May 1965, and 27 March to 19 



Manuscript accepted September 1975 

 FISHERY BULLETIN: VOL. 74, NO. 2, 1976. 



343 



