48 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



suggest any very extensive southward journey of the schools in the 

 autumn after their disappearance from northern coasts. Observa- 

 tions on the behavior of the European mackerel are also consistent 

 with this theory. 



Further, there are certain facts which seem to indicate that the 

 mackerel, when not present at the surface near the coasts, may be 

 in deeper water not far away. In certain bays on the west coast 

 of Ireland large spring mackerel are taken in nets close to shore 

 two or three weeks before any are captured outside in water 40 to 

 80 fathoms deep. This suggests a shoreward movement of the fishes 

 in the deeper layers of water. Also, several cases have been observed 

 of the capture of mackerel by trawls of boats fishing in deep water 

 when the fish were not present at the surface. In one such case a 

 large number of mackerel were taken in trawls at the beginning of 

 March, 1891, at about six miles off Cape Couronne at depths of 50 to 

 75 fathoms. Such facts are consistent with the finding of mackerel 

 in the stomachs of cod taken in American waters some time before 

 the schools had showed at the surface. 



If it be true, then, as the facts known at present seem to indicate, 

 that the mackerel retire to deeper waters to spend the colder months 

 of the year, the question then remains as to whether there is a 

 deeper layer of water accessible to the fish where they can find a 

 temperature similar to that of their summer haunts. That such a 

 substratum of water actually exists is shown by a series of observa- 

 tions taken in 1873 by H. M. 8. Challenger between Bermuda and 

 Halifax, and Bermuda and New York. In the Report of the U. 8. 

 Fish Commission for 1877, Goode has an extended discussion of 

 this matter and shows that out near the Gulf Stream, at a depth 

 of 50 to 100 fathoms, there are, in April and May, extensive layers 

 of water which have a temperature of about 50° F. There is also 

 reason to suppose that similar conditions of temperature exist in 

 parts of the Atlantic off the European coast, though no exact records 

 have been taken in that part of the ocean. 



The evidence which has been adduced above to support the second 



