166 AMERICAN FISHES. 
generalizations. I have there claimed that menhaden make their appear- 
- ance near the shore in the spring as soon as the temperature of the water 
in the harbors has reached a weekly average of 50°, and that they dis- 
appear in the fall soon after the waters have again cooled down to the 
same average temperature. 
The Mackerel are partial to much colder waters. They range ten to 
fifteen degrees farther to the north, and their southern limit is propor- 
tionally high. They appear earlier in the spring and disappear later in 
the fall, and their presence is nearly synchronous with the time when the 
water temperatures of the harbor have reached a weekly average of 45°. 
It has been remarked that the presence of the menhaden depends upon 
a weekly average of the harbor temperature of 50° or more. These harbor 
temperatures are several degrees—it is not known exactly how many— 
higher than those of the open ocean at the same latitude, and there can 
be no question that the menhaden thrives in water as cold as 45°. 
Mackerel will remain active and contented in a temperature of 40°, or 
even less. The normal time of the departure of Mackerel from the coast | 
is, therefore, a month or two later than that of the menhaden. 
There are well recorded instances of the capture of menhaden in Massa- 
chusetts Bay as late as December, and there are also many instances where 
Mackerel have been taken not only on the New England coast, but also 
in the Gulf of St. Lawrence, in midwinter. 
Basing their arguments upon such occurrences as these, Canadian 
writers have attempted to prove that large bodies of Mackerel hibernate 
along their shores in the winter months. It is still believed by many 
fishermen that the Mackerel, at the approach of cold weather, go down 
into the mud and there remain in a state of torpidity until the approach 
of warm weather in spring. All that can be said regarding this theory is 
that, although we do not know enough about the subject to pronounce 
this impossible, American ichthyologists think they know enough to be of 
the opinion that it is very decidedly improbable. 
The appearance of the mackerel schools at the appearance of summer in 
ordinary years has been noticed somewhere in the neighborhood of the 
following dates: At sea, off Cape Hatteras, March 20 to April 25; off 
Norfolk, Va., March 2 to April 30; off the Capes of Delaware, April 15 
to May 1; off Barnegat and Sandy Hook, May 5 to May 25, and at the 
same date along the whole southern coast of New England, and as far 
