[35] HISTORY OF THE MACKEREL FISHERY. 125 



" In these differences of surface temperatures, and the causes which 

 give rise to them, we discover the reason why the mackerel retire, as 

 the summer advances, from the warm coastal waters of the United 

 States out to sea, where they find a stratum of water of the requisite 

 temperature for their free-swimming food.* In the Gulf of Saint Law- 

 rence this requisite temperature is best attained where cold substratum 

 waters are mixed with warmer coastal waters by the tidal waves, the 

 food being at the same time brought inshore by these currents as already 

 described. Here it lingers, partly on account of a suitable temperature 

 being attained, and partly because the efflux and reflux of the tides oc- 

 casion a constant cuxular or elliptical movement of the water. Hence, 

 while the off'-shore waters on the coast of the United States alone pos- 

 sess the requisite degree of coolness in summer for the mackerel food, 

 the inshore waters of tbe gulf acquire the degree of warmth best suited 

 to the habits of these free-swimming creatures, which continues until 

 late in the fall. The question of inshore and off-shore mackerel fishing 

 grounds thus becomes, in a great measure, reduced to the different con- 

 ditions of marine climate which prevail where the Labrador current is 

 the controlling agent, or where the Gulf Stream asserts its power and 

 influence during the summer season." t 



9. — Hind on the causes of the alleged annual variations in 

 the number of mackerel observed. 



"It is well known that the spawn of the herring is deiDosited at the 

 bottom 5 and owing to the glutinous secretion binding the eggs, one to 

 the other, it adheres firmlj'^ to everything which may happen to touch 

 it; and masses of eggs are found to be tightly glued together. But it 

 has been conclusively established by Professor Sars that the mackerel 

 spawn, like that of the cod, floats; and the spawn is developed at the 

 surface of the sea, being drifted to and fro by currents and winds, and, 

 wholly unlike the spawn of the herring, sculpin, smelt, caplin, &c., is 

 at the mercy of the ever- varying currents of the ocean. 



"The taking of mackerel on banks and shoals, dropi^ing their spawn, 

 must be accepted that the fish are ready to spawn at the place where 

 they are then caught. The transparent floating spawn being very diffi- 

 cult to recognize and indeed rarely to be seen, except looked for and 

 caught in tow-nets at the surface of the water. 



* Mackerel are frequently abundant close in to tbe ebores of New England in mid- 

 summer. As a matter of fact large catcbes of mackerel bave been occasionally made 

 in Penobscot Bay, fifteen miles or more inside of tbe outer beadlands and islands. 

 Bluebill Bay, also in Maine, is a famous resort for small and medium-sized mackerel 

 in summer. It is also well known tbat tbe immediate vicinity of Monbegan Island 

 is one of tbe best mackerel grounds on tbe New England coast during tbe montbs of 

 July and August. — J. W. Collins. 



t Fisberies of Britisb Nortb America, pp. 42, 43. 



