FISHERY BULLETIN: VOL. 74, NO. 2 



N.Y 

 PA. 



_ .-T^ t'^>--^Oown%ville (445) 



14031 HancocO 

 (3901 Equ.nunkJ 



Figure l. — The Delaware River. Numbers in parentheses 

 represent distance in kilometers from Marcus Hook, Pa. 



May 1966. Low dissolved oxygen near Philadel- 

 phia blocked upstream passage of part of the 1965 

 spawning run, and few fish were captured at 

 Lambertville (Chittenden 1969); however, 43 

 dead males and 147 females were collected 21 

 May-10 June during a fish kill near Paulsboro, 

 N.J. The gonads of all adults collected were 

 examined to assess their degree of maturation fol- 

 lowing criteria of Leach (1925). 



Data on the abundance of adults in the period 

 1959-62 were obtained from surveys (hereinafter 

 referred to as the Tri-State Surveys) during July 

 and August by the states of New Jersey, New 

 York, and Pennsylvania in cooperation with the 

 U.S. Fish and Wildlife Service. Rotenone was 

 used to collect. After 1962 I made many observa- 

 tions on adult abundance and gonad condition 

 during irregular collections upstream from 

 Dingmans Ferry, Pa., especially during annual 

 float trips in late May between Hancock and Port 



Jervis, N.Y. Observations on behavior during the 

 spawning period were made chiefly in the East 

 Branch near Hancock. 



Young fish were collected in nontidal fresh 

 water from 1963 to 1966 using 12-mm stretch- 

 mesh seines. In 1963, most collections were made 

 from Milford, Pa., upstream into the East and 

 West branches using a 1.8-m deep, 6-m long net or 

 a similar 10.7-m long bag seine. Most seine hauls 

 in 1963 captured few or no young, but a few hauls 

 captured many fish. Quantitative comparisons of 

 abundance were considered unreliable because of 

 the extremely contagious fish distribution. There- 

 fore, techniques were greatly modified in 1964. A 

 22.9-m long, 1.8-m deep net was paid out from a 

 pram. Lights (900 W for 1 h) were used at night to 

 attract young shad to the shoreline for most col- 

 lections during 1964 and thereafter. Only one 

 seine haul was made at a station when lights 

 were used, and collection sites were near deep 

 water. 



During 1966, night seining with lights was con- 

 ducted at 2-wk intervals at Lordville, N.Y, Tus- 

 ten, N.Y, Dingmans Ferry, Belvidere, N.J., 

 Riegelsville, Pa., and Scudders Falls, N.J., from 

 1-4 August to 27-29 September and weekly there- 

 after until 14 November following an unreplicated 

 two-way (stations and collections periods) experi- 

 mental design in which collections were made at 

 each station until the young completely vacated 

 nontidal water. No F tests for significant differ- 

 ences in abundance were possible because of the 

 inherent nature of the study: collecting with lights 

 made catches reliable but replication impossible; 

 intensive seawgird movement of the young by 

 mid-late August caused a stations by collection 

 period interaction which negated tests for main 

 effects. Supplementary collections using lights 

 were made during 1966 in the East and West 

 branches and downstream from Dingmans Ferry 

 (Table 1). 



Nurseries refer herein to areas the young oc- 

 cupy during July and August. Data for 1963, 

 1964, and 1966 (after August) are presented in 

 Chittenden (1969, tables 35, 36, 38, 39, 41). 



SPAWNING PERIOD 



Nearly all spawning apparently occurred 

 within a 3-wk period fi-om about late May to mid- 

 late June, although some spawning extended well 

 into July. No fish had any translucent eggs until 

 early May at Lambertville, and only one running 



344 



