CANADIAN FISHERIES EXPEDITION, 1914-15 483 



temperatures were higher (37-8° — 40° Fj, indicating boreal water. For the banks just 

 south of Newfoundland, Dawson's investigations did not go deep enough, but iljurt 

 failed to find it at the bottom, or only in very small amount at the north. The Chal- 

 lenger, on May 20, 1873, found, just east of La Have bank, water at the bottom with 

 too low salinity and temperature to be boreal. For the early part of the year the boreal 

 water may be absent from the Scotian bank. Bigelow has found boreal water at the 

 mouth of the Bay of Fundy. With the exception of the ChalleiKjer record, for which 

 the season of the year may be responsible, the distribution of the Chaetoguatlis agrees 

 with what has been found as to the extent of the boreal oceanic water. 



As to its origin and movements, we have seen that there is little reason to suppose 

 that the Gulf Stream contributes appreciably to it. It must therefore come either 

 from the deeper part of the Polar current around the outer side of the Grand Banks 

 (its comparative purity at the north as shown by the quantitative distribution of 

 S. maxima and E. hamata support this view) or by upwelling from the depths of the 

 Atlantic, since it is being constantly dissipated by mixture with the coastal water. 

 That it is actually moving toward the southwest seems to be shown by the movement 

 of the centre of abundance of S. serratodentata to the southwest during the summer, 

 and also by the rarity of the boreal species over the Scotian bank, which is an indica- 

 tion that boreal water is passing in that direction and being dissipated. 



The greater abundance of the boreal species on the northern side of the Laurentian 

 channel is an evidence that the boreal water forms part of the current entering the 

 gulf. On its way it must be mixing with the coastal water, as is witnessed by the 

 presence of E. hamata near the surface. This doubtless explains the failure of two 

 of the species to enter the gulf. The third species certainly passes up the Laurentian 

 ichannel as far as the Gaspe coast, although it is unlikely that it reproduces there. 



The boreal oceanic water may be considered as coming from the northeast, and 

 in our region disappearing partly by mixing with the coastal water, particularly in 

 the Laurentian channel, on the Scotian bank and in the gulf of Maine, partly by 

 mixing with the Gulf Stream and returning to the northeast and partly by sinking 

 beneath the Gulf Stream to pass into the Atlantic bottom water. 



In the Northei'n Coastal zone there is only a single species, S. elegans. Young 

 individuals characterize the upper layers, large individuals the lower layers, and very 

 large ones the deepest parts. Fig. 9 shows the distribution in July-August, horizontal 

 lines representing individuals under 20mm., and vertical lines those over 20mm. The 

 general extent of the zone corresponds with the continental shelf, but passes beyond 

 it to some extent in the north, particularly at the mouth of the Laurentian channel. 

 The only parts of the shelf not in the zone are the Xorthumberland strait and the 

 extreme outer part of the Scotian bank. The former is occupied by the southern 

 coastal water, and the latter by the boreal oceanic water. If we exclude the smaller 

 individuals, considering that they belong properly to the southern coastal water, the 

 zone is more restricted, the shallower banks and particularly the Magdalen bay being 

 excluded. This intermediate water containing chiefly the large individuals over 

 20mm. in length has a salinity of from 3lVoo to 33Voo and temperature ranging from 

 about 10° C. down to — 1-5° C. Its apparent absence in the northern part of the gulf 

 will be explained later. Its full development as indicated by the largest individual? of 

 S: elegans occurs in deep fjords like the Bay of Islands, and to a less extent over the 

 Breton bank. The May-June cruises show less difference between the upper and lower 

 layers, large S. elegans being nearer the surface, and therefore in shallower water and 

 more generally distributed. The zone as a whole was at that time more extensive, 

 covering parctically the whole area investigated, extending into Xorthumberland strait 

 and out to the outermost station in the Atlantic. The species was, however, not 

 abundant near these limits nor over the shallower banks. 



The effect of the currents on the coastal water and this coastal species would seem 

 to be the following: The circular motios around the gulf acts as a huge whirlpool and 

 tends to collect S. elegans in the central portions. "Wherever data are available they 



6551—35 



