2 42 AMERICAN FISHES. 



of the water in those localities and at that depth is sure to be less than 

 40° Fahr. How is this fact to be reconciled with the known habits of the 

 fish, that it prefers the warmest weather of summer and swims at the sur- 

 face in water of temperature ranging from 55° to 70°, sinking when cool 

 winds blow below? The case seemed clear enough until the inconvenient 

 discovery was made, that Sword-fish are taken on bottom trawl-lines. In 

 other respects their habits agree closely with those of the mackerel tribe, 

 all the members of which seem sensitive to slight changes in temperature, 

 and which, as a rule, prefer temperature in the neighborhood of 50° or 

 more. 



The appearance of the fish at the surface depends apparently upon tem- 

 perature. They are seen only upon quiet summer days, in the morning 

 before ten or eleven o'clock, and in the afternoon about four o'clock. 

 Old fishermen say that they rise when the mackerel rise, and when the 

 mackerel go down they go down also. 



Regarding the winter abode of the Sword-fish, conjecture is useless. I 

 have already discussed this question at length with reference to the men- 

 haden and mackerel. With the Sword-fish the conditions are very 

 different. The former are known to spawn in our waters, and the schools 

 of young ones follow the old ones in toward the shores. The latter do not 

 spawn in our waters. We cannot well believe that they hibernate, nor is 

 the hypothesis of a sojourn in the middle strata of mid-ocean exactly 

 tenable. Perhaps they migrate to some distant region, where they spawn. 

 But then the spawning time of this species in the Mediterranean, as is 

 related in a subsequent paragraph, appears to occur in the summer months, 

 at the very time when Sword-fish are most abundant in our own waters, 

 apparently feeling no responsibility for the perpetuation of their species. 



The Sword-fish when swimming at the surface, usually allows its dorsal 

 fin and the upper lobe of its caudal fin to be visible, projecting out of the 

 water several inches. It is this habit which enables the fisherman to 

 detect the presence of the fish. It swims slowly along, and the fishing 

 schooner with a light breeze finds no difficulty in overtaking it. When 

 excited its motions are very rapid and nervous. Sword-fish are sometimes 

 seen to leap entirely out of the water. Early writers attributed this habit 

 to the tormenting presence of parasites, but this theory seems hardly 

 necessary, knowing what we do of its violent exertions at other times. 

 The pointed head, the fins of the back and abdomen snugly fitting into 



