[7] HISTORY OF THE MACKEREL FISHERY. 97 



ward in spring and southward in antumn, as that of the ordinary pleas- 

 ure seekers, and their habit of schooling on the surface of the water en- 

 ables us to determine this fact with great precision. Whatever may be 

 the theories of others on the subject, the American mackerel fisher knows 

 perfectly well that in the spring he may find the schools of mackerel off 

 Oape Henry, and that he can follow them northward day by day as they 

 move in countless myriads on to the coasts of Maine and Nova Scotia." 



The movements of the mackerel schools, like those of the menhaden, 

 appear to be regulated solely by the temperature of the ocean. 



In my essay upon menhaden, which has just been referred to, I have 

 attempted to show, in a preliminary way, the relations of the movements 

 of the menhaden schools to the temperature of the water at different 

 stations along the coast in accordance with certain crude observations, 

 which at present constitute the only material available as a basis for 

 such generalizations. I have there claimed that menhaden make their 

 appearance 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 disappear in the fall soon after the waters have again cooled down 

 to the same average temperature. 



The mackerel is 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 450. 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 Mas- 

 sachusetts 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 Saint Lawrence, in mid- winter.* 



* Twenty mackerel were caught in a gill-net at Proviucetown January 17, 1878. 

 Others were taken late in December. Captain Harding tella me that they sometimes 

 come ashore frozen in cold weather, and are found in the ice on the beach. 



Early in February, 18S1, small mackerel 5 or 6 inches in length were found in con- 

 siderable numbers in the stomachs of hake and cod, taken on the eastern part of 

 Greorge's Bank in 50 fathoms, and on the southeastern part of Le Have in 60 and 80 

 fathoms of water; sometimes ten, twelve, or fifteen in the stomach of a single fish. 

 On the 8th and 9th of February, Captain Olsen observed f hem schooling at the surface 

 on George's. Gloucester fishemien had before seen them iu winter on George's, but never 

 BO abundant. 



S= Mis. 110 7 



