HATCHING OF THE YELLOW PEKCH. 
333 
undergoing inspection. The remaining loss occurred among the fry which were held 
in the aquaria under observation one and two weeks. Probably no other eggs ever 
handled by the Commission were so hardy as these. 
After becoming water -hard the yellow-perch egg-strings are larger than the 
parent fish. The 88-inch string previously referred to weighed 41 ounces avoirdupois, 
while the parent fish would not have exceeded 14 ounces previous to spawning. The 
length and weight of her eggs, as well as the size of the spawning fish, were person- 
ally verified by me. The eggs being of less specific gravity occupy relatively more 
space than the yellow perch themselves. 
Table of yellow-perch egg -production at Central Station, Washington, D. C., 1890. 
This large yield of eggs was far beyond my most ardent expectations, producing 
for actual introduction into the streams 754,000 fry. The eggs were developed in twenty- 
two of the universal hatching jars, their weight being sufficient to keep them well 
down at the bottoms. No eggs could have been a less care, it being only necessary to 
prevent them from being enveloped in sediment. This was done by increasing the 
current at times and keeping them in rapid motion till the mud was washed away. 
No jar motion was employed in the hatching. 
While undergoing hatching the young, as in shad-hatching operations, were 
automatically separated into the collectors. When any dead eggs were discovered, a 
rare occurrence, it was usually found that the whole lobe was defective. As the lobe 
could be removed intact and with onemotion of the hand-net, the picking was no trouble 
whatever. Therefore, in simplicity of manipulation, economy of labor in attendance, 
and in turning out a large percentage in hatching, the yellow perch may be said to 
rank at the head of the list. 
Four, three, and two weeks were occupied in hatching, the period being modified 
by temperature. On the 17th of April 754,000 fry were released, 704,000 in the Poto- 
mac and 50,000, as an experimental plant, in a private pond near Washington. The 
parent fish, after all spawning was concluded, were set free again in the Potomac. 
