328 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



have been made. 62 Mackerel also spawn to some 

 extent thence northward, as far as Casco Bay, but 

 we believe very few do so farther east than that 

 along the coast of Maine. Neither is it likely that 

 mackerel breed successfully in the northern side 

 of the Bay of Fundy for neither eggs nor larvae 

 have been taken there though some production 

 may take place on the Nova Scotian side for 

 Huntsman reports eggs at the mouth of the An- 

 napolis River. And while a moderate amount of 

 spawning takes place along the outer coast of 

 Nova Scotia, 63 it seems that the eggs do not hatch 

 in the low temperatures prevailing there, for no 

 larvae have been found. But the southern side 

 of the Gulf of St. Lawrence, where the surface 

 waters warm to a high temperature in summer, 

 is an extremely productive spawning ground (p. 

 322). 



Since the large adult mackerel tend to keep 

 farther offshore than the small ones (p. 328), such 

 of them as spawn in our Gulf do so at least a few 

 miles out. Very few eggs, for example, were 

 found in 1897 (a year of plenty) in the inshore 

 parts of Casco Bay, 64 though this was formerly 

 thought to be a productive spawning ground. 



Once the mackerel have entered our Gulf, 

 schools are to be expected anywhere around its 

 coastal belt, at any time during the summer; also 

 on Nantucket Shoals, on the western part of 

 Georges Bank, and on Browns Bank, as just noted 

 (p. 327). And while adult fish seldom venture 

 within the outer islands or headlands, good catches 

 of them have been made well up Penobscot Bay, 

 and young ones 6 to 10 inches long often swarm 

 right up to the docks in various harbors in summers 

 of plenty. 88 



Mackerel are proverbially unpredictable in their 

 appearances and disappearances at any particular 

 place, hence the common saying that "mackerel are 

 where and when you find them." This is partly 

 because the schools are constantly on the move, 

 but partly because it is only while they are school- 

 ing at the surface or near it that they are seen. 



" Subsequent information, and especially the result of tow nettings on the 

 southern grounds in 1929, 1930, 1931, and 1932 (Sette, Fish. Bull. U. S. Fish 

 and Wildlife Service, vol. 50, Bull. 38, 1943) have shown that the Gulf of 

 Maine as a whole is much less productive than the more southern spawning 

 grounds, not more so as Bigelow and Welsh (Bull. U. S. Bur. Fish., vol. 4, 

 Ft. 1, 1925, p. 206) believed. 



" Sparks, Contrib. Canadian Biol, and Fish., N. Ser., vol. 4, No. 28, 1929. 



'< Moore, Rept. U. S. Comm. Fish. (1898) 1899, p. 16. 



« Sette (Fish. Bull. U. S. Fish and Wildlife Service, vol. 51, Bull. 49, 1950, 

 p. 297) discusses this point further. 



When they sink to lower levels in the water, as 

 they often do, they drop out of sight entirely, 

 unless some of them chance to be picked up by 

 drift netters. Large mackerel are more prone to 

 disappear in this way than small ones, especially 

 in late summer or early autumn. In 1906, for 

 example, the schools of large fish vanished from 

 the Massachusetts Bay region in June, to reappear 

 the 27th of July, on which date 28 seiners made 

 catches ranging from 18 to 250 barrels each. And 

 in 1S92, a year of abundance, they disappeared 

 (that is, sank) in August, not to appear again in 

 any abundance anywhere in the Gulf of Maine 

 until October. 



The view has grown that when this happens the 

 mackerel have deserted the Gulf for the time being. 

 But it was common knowledge in the days before 

 the introduction of the purse seine, when it was 

 the regular practice to lure the fish to the surface 

 by throwing out ground bait, that large mackerel 

 summer as regularly in the Gulf as small, and that 

 good hook-and-line catches of large fish could be 

 made in one or another part of the Gulf through 

 the season from June to October, even when none 

 showed at the surface. 



Their disappearances in summer merely mean 

 that the fish have sought lower levels in the water; 

 that they have wandered to some other part of the 

 Gulf; or perhaps that the schools have dispersed 

 more or less. When they sink in summer in our 

 Gulf, it is not likely that they descend very deep. 

 In the first place the water deeper than about 

 40 to 50 fathoms is colder than 46°-47° F. (8° 

 C), i. e., than they seem to prefer; in the second 

 place the planktonic animals on which they feed 

 are more concentrated above the 50-fathom level 

 than deeper. And a year comes, now and then, 

 when mackerel of all sizes school at the surface 

 all summer long. 66 



Sette's 67 painstaking analysis of the relative 

 frequency with which schools are seined in different 

 localities has shown that mackerel are seen far the 

 most often in the southwestern part of the Gulf 

 and out along the western part of Georges Bank, 

 with the chief concentrations in one part or another 

 of Massachusetts Bay and off the outer shore of 

 Cape Cod to Nantucket Shoals, though great 

 numbers are also caught along the Maine coast, 

 close inshore. 



'• 1882 was an example of this. 



" Fish. Bull. U .S. Fish and Wildlife Service, vol. 51, Bull. 49, 1950, p. 

 297, fig. 17. 



