Section IV, 1918 [61] Trans. R.S.C. 



The effect of the Tide on the Distribution of the Fishes of the Canadian 



Atlantic Coast. 



By A. G. Huntsman, B.A., F.R.S.C. 



(Read May Meeting, 1918.) 



On the Atlantic coast there are two large gulfs, each connected 

 with the open ocean by openings which are traversed by ancient 

 river beds, now submerged a hundred fathoms or more below the 

 surface. These are the gulf of St. Lawrence at the north and at the 

 south the gulf of Maine which is continued into the bay of Fundy. 

 The tidal conditions in these two bodies of water differ greatly. In 

 the gulf of St. Lawrence the rise and fall are slight amounting to 

 from 3 to 8 feet, while in the gulf of Maine and particularly in the 

 bay of Fundy the rise and fall are very great, reaching a maximum of 

 about fifty feet at the head of the bay of Fundy. We purpose con- 

 trasting this latter region with the gulf of St. Lawrence. 



The heavy tides in the bay of Fundy produce strong currents, 

 which flow over many shoals and through narrow passages. These 

 heavy tide-rips and whirlpools mix the water very effectually so that 

 there is little difference to be found between that at the surface and 

 that at the bottom. This condition seems to reach its extreme on the 

 northwest side of the bay, where in Charlotte county. New Brunswick, 

 is an assemblage of islands of many sizes and irregular shapes, to which 

 the name of Western Archipelago has been given. 



From the earliest times the cold character of the water in this 

 region has been noted. Rarely does it at any point reach a tempera- 

 ture higher than 53 degrees F. even by the end of the summer, and the 

 mass of the water remains constantly below that temperature. In the 

 winter the greater part of the water cools nearly to 32 degrees F. and 

 much of it, particularly in the estuaries, goes below that temperature. 



In the gulf of St. Lawrence a distinctly different picture is pre- 

 sented, which finds its maximum development on the Magdalen 

 shallows, just across the Chignecto isthmus from the head waters of 

 the bay of Fundy. A large shallow bay surrounds the Magdalen and 

 Prince Edward islands, and in it the tides are slight, there is an absence 

 of narrow passages, and shoals are few. There cannot be, therefore, 

 much mixing of the water. As a result we have a definitely stratified 

 condition, which is most prominent at the end of summer. Briefly 

 there are two principal layers in the water of the Magdalen shallows; 



