102 FISH—-CULTURAL ASSOCIATION. 
a 
South of the cruising ground the dates of arrival and depar- 
ture are doubtless farther apart; north and east the season 
shorter. There are no means of obtaining information, since 
the men engaged in this fishery are the only ones likely to re- 
member the dates when the fish are seen. 
REASONS OF THE COMING OF SWORDFISH UPON OUR COAST. 
The swordfish comes into our waters in pursuit of its food. 
At least this is the most probable explanation of their move- 
ments, since the duties of reproduction appear to be performed 
elsewhere. Like the tunny, the bluefish, the bonito, and the 
squeteaguc, they pursue and prey upon the schools of menhaden 
and mackerel, which are so abundant in the summer months. 
“When you see swordfish you may know that mackerel are 
about !’”’ said an old fisherman to me, ‘‘ Where you see the fin- 
back whale following food, there you find swordfish !” said an- 
other. The swordfish also feeds upon squid, which are at times 
abundant on our banks. 
THE INFLUENCE OF TEMPERATURE UPON THE MOVEMENTS OF THE 
SWORDFISH. 
To what extent this fish is amenable to the influences of tem- 
perature is an unsolved problem. We are met at the outset by 
the fact that they are frequently taken on trawl lines, which are 
set at the depth of one hundred fathoms or more on the off-shore 
banks. We know that the temperature of the water at those lo- 
calities, and at that depth, is sure to be less than forty degrees 
Fahrenheit. How is this fact to be reconciled with the known 
habits of the fish, that it prefers the warmest weather of sum- 
mer, and swims at the surface in water of temperature ranging 
from fifty-five to seventy degrees, sinking when cool winds 
blow? The case seemed clear enough until this inconvenient 
discovery was made, that swordfish 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 the temperature, and which, as a rule,;prefer 
temperature in the neighborhood of fifty degrees or more. 
