SURFACE WATERS OFF THE CANADIAN PACIFIC COAST 573 



The surface temperatures observed during the four cruises are 

 shown in Figure 4. During the summer the water along the coast is 

 cold, particularly in the approaches to Juan de Fuca Strait. This cold 

 coastal belt corresponds to the region of fresh water influence shown 

 in the previous figure. The temperature of the surface zone increases to 

 seaward. 



In August 1950 there were several clouds of warm water lying in 

 a band extending due south from the Queen Charlotte Islands and be- 

 coming warmer towards the southern limit of the area. Thus tlie coldest 

 and wannest regions were contiguous. West of the warm belt the 

 water became colder in all latitudes, the minimum temperatures being 

 similar to those in the approaches to Juan de Fuca Strait. 



In August 1951 the characteristic band of cold coastal water was 

 again present, and the temperatures increased to seaward. However, in 

 the offshore regions the isotherms crossed the area essentially normal 

 to the coast. The principal gradient instead of being east-west as in the 

 previous year, was practically north-south. Although the average tem- 

 perature was two degrees higher in 1951, the range was smaller. This 

 picture is a distinctly different type of situation from that observed 

 in the previous year. 



It is interesting to note in passing that during August 1950 vast 

 numbers of vellela were observed throughout the entire areas of this 

 survey west of Longitude 130°W. Large numbers were visible at all 

 times, and they frequently occurred in such concentrations as to look 

 like great streaks of foam on the water. By the crudest of calculations 

 it was estimated that the number in the area between Longitude 

 141 °W and the coast would be of the order of 10" to IO12, and it is 

 not known how much further they extended in all directions. In 

 August 1951, on the other hand, when tlie water was warmer, not a 

 single specimen was observed throughout the cruise. 



In winter the warmest water was along the shore, and became 

 colder to seaward. It appears likely that this condition is typical of 

 winter and spring. 



The dynamic topographies of the sea surface shown in Figure 5 

 indicate that the currents are weak and variable. In the summer the 

 currents do not exceed two miles a day (4 cm. /sec). They are so sinu- 

 ous that there appears to be no resolution of flow in the southern 

 part of the area. However, there is a general tendency for water to 

 enter from the south and west, and leave to the north. This results 

 in some degree of convergence and acceleration towards the northern 

 limit of the area. The two August and the May surveys were made 

 during periods of northwest winds which oppose and retard the net 

 flow. The northward tendency is much stronger in the winter (March 



