[11] THE SPANISH MACKEREL. 405 
As has been said, the spawning season for our coast continues through- 
out the entire summer, and, in any particular locality, it lasts from six to 
upwards of ten weeks. The time of spawning for individuals of the same 
school varies considerably, the ovaries of some of the fish being fully 
mature while those of others are still quite green. Again, a single indi- 
vidual is a number of weeks in depositing its eggs, as shown by the fact 
that when the first are excluded a large percentage are still small and 
immature. All of the eggs in the ovaries of a shad, salmon, or white- 
fish develop uniformly, and the whole number are deposited at about 
the same time, so that the spawning season for the individual lasts only 
a few days at most. Up to the winter of 1878~79 it had been supposed 
that all fishes were alike in this particular; but our study of the cod at 
that time proved that the individuals of that species were several months 
in depositing their eggs, and the same is found to be true, within smaller 
limits, of the Spanish mackerel. 
The number of eggs varies with the size of the parent fish, that for a 
one-pound mackerel being estimated at 300,000, while that for a six- 
pound fish can searcely be less than 1,500,000. To ascertain definitely 
the number for the average fish, an immature female, weighing one pound 
and thirteen ounces, and measuring 184 inches was selected, and the num- 
ber of eggs was carefully computed. The ovaries, when placed on accu- 
rately adjusted balances, were found to weigh 34.275 grams. These were 
then opened, and a 100 milligrams, selected from different portions of the 
roe-bags, so that all sizes might be represented, were weighed out. When 
counted this mass was found to contain 1,536 eggs. From these data it 
was found that the ovaries of the fish should contain 526,464 eggs. This 
number would be too great, as no allowance was made for the weight 
of the ovary walls; allowing for these, the number would be not far from 
525,000. Itis thus seen that the species is more prolific than the salmon, 
shad, or white-fish, though it is much less so than many of the gadoids, 
a 75-pound codfish yielding fully nine millions. 
The eggs of the Spanish mackerel are smaller than those of any other 
species with which we are familiar. During the early part of the season 
they can scarcely be distinguished by the unaided eye, and although 
they gradually increase in size, when fully ripe they have a diameter,— 
varying somewhat with the size of the parent and the condition of the 
eggs when pressed from the ovaries—of only one twenty-second to one 
twenty-eighth of an inch. Most of those secured by us were of the.last- 
named size, and taking these as a basis it will be seen that a cubic inch 
would contain 21,952 eggs, and that 1,267,728 could be placed in a quart 
cup. 
After impregnation the eggs have a specific gravity between that ot 
fresh and salt water, as shown by the fact that they sink in one and 
float in the other. When thrown from the parent they rise to the sur- 
face, and are driven hither and thither by the winds and tides during 
the earlier period of development. Many are lost from lack of fertiliza- 
