FISHERY BULLETIN: VOL. 74, NO. 2 



this was the spawning act. However, the vigorous 

 splashing and noise is similar to the observations 

 of Goode (1888) and Leach (1925) and of Leim 

 (1924) who used plankton nets to collect newly 

 fertilized eggs. 



Light intensity seemed to regulate when 

 spawning began each day, and the shad seemed to 

 prefer shallow riffle areas for this activity. Few 

 fish were observed during the day in a shallow 

 riffle spawning site near Hancock, but many fish 

 moved from the upstream pool to the riffle as 

 evening approached. Concentration near the 

 riffle occurred earlier on overcast days than on 

 sunny days. I observed spawning only at night in 

 general agreement with Pennsylvania (1875), 

 Goode (1888), Leim (1924), Leach (1925), Walburg 

 and Nichols (1967), and Marcy (1972). In contrast, 

 Massmann (1952) found spawning at all hours in 

 the Pamunkey River, Va., although possibly more 

 intensively fi:-om noon to midnight. Water turbid- 

 ity probably influences the effect of light in reg- 

 ulating the daily onset of spawning. Spawning 

 probably tends to occur at night in clear water 

 such as the upper Delaware, but seems to begin 

 later during the day or occurs all day long in tur- 

 bid water typical of tidal areas such as the 

 Pamunkey River. Overcast skies apparently per- 

 mit spawning to begin earlier in the day. 



SPAWNING GROUNDS 



Important spawning grounds apparently ex- 

 tend no farther downstream than the Belvidere 

 area. During the Tri-State Surveys, greatest 

 numbers of adults were captured from Minisink 

 Island to Skinners Falls, and none were captured 

 downstream from Manunka Chunk (Table 2). 

 Few adults were captured from Long Eddy, N.Y., 

 upstream. However, these collections were made 

 10-21 July which is well after most adults move 

 seaward or die (Chittenden 1976). Therefore, the 

 chief spawning grounds may have been farther 

 upstream. 



Extensive observations from 1962 to 1968 gen- 

 erally support the Tri-State Survey collections, 

 but in contrast they suggest that the area from 

 Skinners Falls to the lower East Branch was ex- 

 temely important. Many adults were observed 31 

 May-1 June 1962 from Milford to Delaware Water 

 Gap, and 30 May-5 June 1963 from Mongaup 

 River (km 296) to a few kilometers above Calli- 

 coon, N.Y. (km 360). In 1964, hundreds of adults 

 were observed near Hancock and the lower East 



Branch 29 May-20 June and (J. Musick pers. 

 commun.) near Milford on 31 May. Fewer adults 

 were observed after 1964, but they consistently 

 appeared from Sparrowbush, N.Y. (km 286), to the 

 lower East Branch in late May and early June. 



Table 2. — Numbers of adult American shad captured during 

 the Tri-State Surveys. 



Some spawning occurs downstream of Philadel- 

 phia; however, few fish which pass Philadelphia 

 spawn as far downstream as Lambertville. I col- 

 lected a nearly spent male on 10 June 1965 at 

 Marcus Hook. This fish undoubtedly had spawned 

 nearby, because low dissolved oxygen would have 

 prevented movement past Philadelphia after 

 April (Chittenden 1969). The Lewis Fishery at 

 Lambertville captured about 6,300 fish from 1963 

 to 1968, but only 21 were taken after 15 May. 



Spawning extends into the lower West and East 

 branches, especially the latter, but dams prevent 

 movement upstream of Stilesville, N.Y., and 

 Downsville, N.Y. Young shad (27 mm total length) 

 were captured in the West Branch at Hancock on 9 

 August 1963 (Chittenden 1969, table 26). This 

 suggests spawning there because net movement of 

 the young is downstream. Adults were collected in 

 the East Branch at Hancock during the 1961 Tri- 

 State Surveys. Many occurred at least as far up- 

 stream as East Branch, N.Y. (km 430), in the runs 

 of 1962-65 (W. Kelly pers. commun.; my observa- 

 tions). I observed spawning in the East Branch 

 near Hancock in 1964 and 1965. 



The adults ascend some tributaries, but it is not 

 certain if they spawn there. A female was caught 

 on 16 May 1961 in Big Flat Brook (km 235) about 

 10 km upstream from the Delaware (Anonymous 

 1961). Adults ascended several kilometers up the 

 Mongaup River from 1962 to 1964 and 6 km up the 

 Beaverkill River, an East Branch tributary (W. 

 Kelly pers. commun.). 



346 



