EFFECTS OF THE MENHADEN AND MACKEREL FISHERIES 
UPON THE FISH SUPPLY. 
& 
By W. C. KENDALL, 
Assistant, United States Bureau of Fisheries. 
& 
SCHOOLING OF FISHES. 
There are various degrees of gregariousness among fishes. Probably there are 
but few fishes that do not swim in schools at some stage of their existence, and 
there are few, if any, that are always in schools. The very young of most species, 
as a rule, occur in schools of greater or less extent. The broods of fishes from 
ova laid in more or less stationary collections or floating agglutinated masses 
naturally occur in family groups of brothers and sisters. Floating eggs, while 
sometimes scattered, are perhaps oftener assembled through the effects of winds, 
minor currents, etc. The young from such eggs to some extent constitute 
brotherly and sisterly aggregations, though probably they are more frequently 
mixed broods. Some species commonly regarded as nongregarious are occasion- 
ally observed in schools in their young or adult stages. 
The schooling habit is socommon among fishes that it must in some way be 
an advantage to them, although it not infrequently is an obvious and decided 
disadvantage. The most pronounced types of gregarious fishes are comprised 
in the scombroid and clupeoid groups, but among the species of these groups 
there is considerable diversity in respect to the habit. The most representa- 
tive and perhaps the most perfect examples of the schooling fishes of these two 
great groups are, respectively, the common mackerel and menhaden. 
The eggs of the mackerel float. They are supposedly deposited at the 
bottom, whence they rise to the surface and are subject to the influences of winds, 
waves, and currents, which factors determine whether they shall be scattered or 
aggregated. 
Practically nothing is known of the place of spawning of the menhaden or the 
character of its eggs—whether agglutinated, attached to objects, or free, or 
whether they sink or float. But the fact remains that as soon as the young of 
either the mackerel or the menhaden are observed they are in schools. The 
very young of either species have not been observed except in the case of arti- 
281 
