NOTE Bllkovic et al.: Spawning of Alosa sapidissima and Morone saxatilis 



633 



kilometers 

 40 



Figure 1 



Extent of ichthyoplankton sampling by bongo net and pushnet in the Mattaponi and Pamunkey rivers (1997-99). Stations are 

 denoted as the number of kilometers from the mouth of the York River. 



can shad [Leach and Houde, 1999; Walburg and Nichols^] 

 and salinity requirements for the early life stages of these 

 species, the potential for spawning overlap spatially and 

 temporally is high. Species interactions, including preda- 

 tion and competition by both adults and young, may play a 

 role in the spawning and recruitment success of these spe- 

 cies. Similar interactions have been postulated between 

 American shad and other alosines in the Hudson River 

 (Schmidt etal, 1988). 



Our objectives were to describe the American shad 

 spawning reaches in the Mattaponi and Pamunkey Rivers 

 spatiotemporally, and to determine if striped bass also 

 spawn within the identified spawning habitat of American 

 shad. In year one, we completed an exploratory survey 

 to map the distribution of the American shad spawning 

 ground and the occurrence of striped bass within these 

 reaches. In years two and three, sampling was modified to 

 locate the upper limit of American shad and striped bass 

 spawning within the two rivers. 



^ Walburg, C. H., and P R. Nichols. 1967. Biology and man- 

 agement of the American shad and the status of the fisheries, 

 Atlantic coast of the United States, 1960. U.S. Fish and Wild- 

 life Service, Special Scientific Report-Fish .550, 105 p. Fish 

 and Wildlife Service, U.S. Dep. of Interior, Washington, DC 

 20005. 



Materials and methods 



Sampling protocol in 1997 



Exploratory sampling in the Mattaponi and Pamunkey 

 rivers for eggs and lai^ae of American shad and striped 

 bass extended from March through April 1997. Sites were 

 chosen on the basis of a prior survey of American shad 

 eggs in the rivers (Massmann, 1952). Sampling protocol 

 included weekly ichthyoplankton collections during day- 

 light hours with stepped oblique tows of a bongo frame 

 fitted with two 333-pm mesh nets (60-cm diameter). 

 Catches from both nets were combined. The same ten 

 stations were sampled weekly on each river within the 

 tidal freshwater reaches. Stations are depicted as river 

 kilometers (rkm) from the mouth of the York River, for 

 example, M68 is a station on the Mattaponi River that is 

 approximately 68 river kilometers from the mouth of the 

 York River The stations were located at approximately 

 3.2-rkm intervals within the range of 72 to 106 rkm (P72 

 to P106) on the Pamunkey River and 68 to 102 rkm (M68 

 to M102) on the Mattaponi River (Fig. 1). 



Sampling protocol in 1998 and 1999 



In 1998 and 1999, station locations were extended upriver 

 to include more shallow stations owing to the low abun- 



