SPAWNING HABITS OF THE SHAD. 
205 
Another seine, operated just below Oldman Creek, appears, in consequence of its 
detached situation, to have been passed over by spawn-collectors, and we have no 
data relating thereto. If this seine is not wholly without the spawning region by 
virtue of its seaward location, it will doubtless be found very productive of spawn 
and, should this prove to be the case, will probably afford the choicest site on the 
Delaware for a permanent shad station. 
The Potency of Greeks . — That the higher temperature of the creek water is chiefly 
the controlling factor in drawing shad to these localities to spawn, I have no reason- 
able doubt. That the creek water, as a separate volume, is itself preferred as an 
element to spawn in, is evidently not the case ; for observation on the catch of the seine 
operated by the Raum family in Broad Creek proper (2 miles above Fort Washington 
station, Potomac river) shows that this fishery possesses no value as an instrument of 
egg-production. Apparently the warmer water of the creeks becomes an active influ- 
ence only when commingling with the colder river volume, or when effecting a mean 
between the two extremes in temperature. How far bottom may exert an influence I 
am unable to judge; it is not impossible that a greater amount of sand and gravel dis- 
tributed over these areas by the creeks gives them a somewhat preferred character, 
but I do not think that this feature enters into the question except in a minor wav, 
if at all. 
Commissioner McDonald has pointed out that shad are controlled by tempera- 
ture, they being always found within given limits of beat and cold; that they enter 
the estuaries as soon as these waters become warmer than that of the ocean, and 
that they ascend the fresh water streams in quest of the higher zone of heat, the 
mean temperature sought being about 60° F. Now, since they spawn about or soon 
after the sunset hour (between the hours of 5 and 10 p. m.), it becomes evident that 
they prefer, for this act, neither the highest nor the lowest temperature of the 24-hour 
period, for the highest degree prevails earlier in the afternoon on the flats and in the 
creeks, while the lowest is existent in the early morning. 
The fact that spawning shad caught in the warmer water on wide flats remote from 
the river channel are unaccompanied by sufficient bucks to afford milt for impregnating 
their eggs suggests that these localities are abnormal for spawning. It is possible, 
but rather improbable, that sufficient bucks do accompany the females, but, owing to 
their smaller size, escape the meshes of the gill nets. 
On the other hand the, spawning between midnight and noon, or in the coldest 
water of the 24-liour period, is very light. Experience satisfies me that even the low 
production by the Fort Washington seine is greater than at other fisheries (see two 
years’ record of this seine below) : 
Year. 
A. M. (12 o’clock 
midnight, to 12 
o’clock meridian) 
eggs. 
P. M. (12 o’clock 
meridian to 12 
o’clock midnight) 
eggs. 
Total eggs. 
Percentage 
of A. M. 
eggs. 
Percentage 
of P. M. 
eggs- 
1887 
*3, 095, 000 
tl, 858, 000 
17, 861, 000 
20, 799, 000 
20, 956, 000 
22, 657, 000 
14 
8 
86 
92 
1888 
* Taken during 19 days, April 16 to May 23. t Taken during 16 days, April 16 to May 26. 
