300 NATURAL HISTORY OF AQUATIC ANIMALS. 



change its color to that of the sand so perfectly as to be almost invisible. In this way it would 

 wait until the fishes eaine back, and when they were swimming close to or over the ambuscade, the 

 squid, by a sudden dart, would be pretty sure to secure a fish. Ordinarily when swimming they 

 were thickly spotted with red and brown, but when darting among the Mackerel they appeared 

 translucent and pale. The Mackerel, howevei', seemed to have learned that the shallow water is 

 the safest for them and would hug the shore as closely as possible, so that in pursuing them many 

 of the squids became stranded and perished by hundreds, for when they once touch the shore they 

 begin to pump water from their siphons with great energy, and this usually forces them farther 

 and farther up the beach. At such times they often discharge their ink in large quantities. The 

 attacks on the young Mackerel were observed mostly at or near high water, for at other times the 

 Mackerel were seldom seen, though the squids were seen swimming about at all hours; and these 

 attacks were observed both in the day and evening." 



The dogfish is doubtless a dangerous foe to the Mackerel weakened by the act of spawning 

 and remaining near the bottom. An old fisherman has described to me with great animation how 

 greedily the dogfish devour the Mackerel which have become gilled in the nets, how they follow 

 them to the surface and linger about the vessel while the process of cleaning is going on, drinking 

 the blood of the fish as it flows from the scuppers. 



STUDIES OF THE MOVEMENTS OF THE MACKEREL SCHOOLS. 



HIND ON THE CAUSES OP IRREGULAR MOVEMENTS. In closing this chapter upon the 

 natural history of the Mackerel, it seems appropriate to quote from the writings of Professor Hind 

 some very important paragraphs in which he has attempted to interpret the irregular movements 

 of the mackerel schools in our waters, and to explain the causes of the alleged annual variation 

 of their numbers: 



"What is the proper interpretation of the movements of the Mackerel from its first appear- 

 ance in the spring to its disappearance in the fall? These movements vary with the geographical 

 position of local schools of this fish. On the coasts of the United States and Nova Scotia, its 

 annual movements resemble in all particulars those of the same species in European seas where 

 the schools have a free and unobstructed ocean in which to seek their prey. 



"In the spring, at the end of April and May, the Atlantic schools of this fish which have 

 wintered off the coasts approach the land in separate bodies, full of spawn and poor, coming direct 

 from winter homes where they have remained in a torpid condition, partially buried in sand or 

 mud. After spawning, the different schools feed for a short time on the fry of fish, and as the 

 temperature rises they go out to sea in search of free-swimming crustaceans and larval forms of 

 food according as they are distributed by wind and tide. 



"They pursue this food against the current or tide. They often feed during the night, because 

 at that period great numbers of free-swimming larval forms approach the surface. This is one 

 reason why mackerel schools are frequently missed by fishermen, and areas supposed to be deserted 

 may really abound with this fish, which would be discovered by sink-net fishing. The currents 

 are constantly changing with the seasons under the influence of temperature and prevailing winds, 

 hence the course of direction and depth of the food is constantly changing also. 



"Sometimes it is carried far off from the land, at other times towards it, and the mackerel 

 schools following the food move first in one direction, then in another, and range from close inshore 

 to fifty miles and more seawards, and often, doubtless, at a considerable depth below the surface. 



"The general direction of these movements, when plotted on paper, would be a series of irregu- 



