PIKES AND PIKE PERCH Zi: 
COMMERCIAL IMPORTANCE 
Throughout most of its range the yellow perch occupies an im- 
portant place in the commercial fisheries and is highly esteemed. 
From the Great Lakes, the Potomac River, and the smaller lakes of 
the upper Mississippi Valley large quantities are taken every year 
by means of fyke nets, gill nets, traps, seines, and lines and find a 
ready market. The annual catch approximates 5,700,000 pounds, 
valued at $384,000, about 86 per cent being credited to the Great 
Lakes. 
SPAWNING SEASON AND CHARACTER OF EGGS 
The spawning season of the yellow perch occurs on a rising water 
temperature in late summer or early spring. In the Potomac River 
this fish spawns in February, March, or April, depending upon 
climatic conditions. The eggs, which are of a light color and semi- 
transparent, are remarkable from the fact that when deposited they 
are joined together in a greatly elongated, ribbonlike mass. One 
end of the mass, corresponding to the anterior end of the roe, is 
larger than the other end and bluntly forked. The length of the 
string varies from 2 to 7 feet, depending upon the size of the fish, 
but it may be much compressed lengthwise because of its arrange- 
ment in regular transverse folds, like the sides of a bellows. Upon 
deposition the eggs are in loose, globular form, but after being fer- 
tilized and water-hardened the mass becomes many times larger 
than the parent fish. It is recorded that a female yellow perch under 
observation in an aquarium deposited a string 88 inches long, 4 inches 
wide at one end, and 2 inches wide at the other. The weight of this 
mass after fertilization was 41 ounces avoirdupois, while the weight 
of the fish shortly before it had spawned was only 24 ounces. 
Throughout the entire length of the string there is a cavity, its 
walls being formed by the delicate membrane surrounding the eggs. 
Small apertures occur in this column at irregular intervals, their 
purpose apparently being to permit the free circulation of water to 
facilitate incubation. 
At the Cape Vincent (N. Y.) hatchery, where a careful count 
was conducted, a quart of green eggs was found to number approxi- 
mately 100,000, while the number per quart, after being fully swollen, 
was reduced to 36,000. These figures can not be adopted as standard, 
however, since there is a wide variation in the size of the eggs taken 
in different regions. 
The incubation period in a mean water temperature of 47° EF. covers 
about 27 days. The egg sac is absorbed in about five days. 
ARTIFICIAL PROPAGATION 
The source of egg supply of this species consists principally of 
adult fish procured from market fishermen and allowed to spawn 
naturally in tanks of running water or in floating boxes or pens. 
These boxes are made of seven-eighths-inch material and are about 
8 feet long, 4 feet wide, and 4 feet deep. In their construction a 
solid board, to form the bottom, is fastened to four corner posts. 
