314 NATURAL HISTORY OF AQUATIC ANIMALS. 



are very much enlarged. By the 1st of June occasional ripe fish are seen. The spawning season 

 proper begins about two weeks later, and continues during the greater part of the summer. The 

 fisliermen report many of the Mackerel to be full-roed when they reach the Sandy Hook region, 

 and claim that t>y the last of August the eggs begin to separate and run from the female. From 

 this date to the close of the season numerous individuals are taken from which eggs or milt will 

 run freely. 



"The limits of the spawning grounds have not yet been definitely ascertained, though enough 

 has been learned to show that the Mackerel spawn at numerous points between Narragansett 

 Bay and South Carolina, and it seems probable that when a thorough investigation is made the 

 southern limits will be found to extend as far as Mississippi, and perhaps to Texas. It is certain 

 that they spawn in some of the sounds of the Carolinas, in Chesapeake Bay, off Sandy Hook, and 

 along the southern shores of Long Island; the Chesapeake and Sandy Hook regions being visited 

 by immense numbers of Mackerel for this purpose. 



"As has been said, the spawning season for our coast continues throughout 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 individual 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 whitefish 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 scarcely 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 eighteen and a half inches, was selected, and the number of eggs 

 was carefully computed. The ovaries, when placed on accurately adjusted balances, were found 

 to weigh 34.275 grams. These were then opened, and 100 milligrams, selected from different por- 

 tions of l he roe-bags, so that all sizes might be represented, were weighed out. When counted 

 this mass was found to contain 1,5 .6 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. It 

 is thus seen that the species is more prolific than the salmon, shad, or whitefish, though it is 

 much less so than many of the gadoids, a seventy-five-pound codfish yielding fully 9,000,000. 



"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 of 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 surface and are driven hither and thither by the winds ind tides during the earlier 

 period of development. Many are lost from lack of fertilization, others are destroyed by the 

 animals of the water, and considerable quantities are doubtless driven upon the shore during 



