708 EIGHTH PACIFIC SCIENCE CONGRESS 



of these typical regions. Once the oceanographic conditions of an area 

 have been determined for each season of the year by means of oceano- 

 graphic surveys, it is only necessary to refer to the daily seawater records 

 to recognize annual changes in the properties of the water. Thus, Lan- 

 gara and Cape St. James record the exposed open ocean regions; Triple^ 

 Sandspit, Ivory, Entrance, Texada, Departure Bay and East Point record 

 the protected coastal regions; Kains and Amphitrite record the exposed 

 coastal regions; and Pine, Cape Mudge and Race Rocks record the tur- 

 bulent sea-ways. The Pacific coastline of Canada is so extensive that 

 these typical oceanic regions occur in widely separated locations where 

 the determining factors of meteorological conditions, fresh water runoff, 

 and tide might be quite different in magnitude. This is especially 

 true of the region of Georgia Strait, where the extensive variation in 

 local geographic conditions creates several sub-classes of oceanic regions. 



The oceanography of the Georgia Strait (Fig. 1) is dominated by 

 the fresh water discharge from the Eraser River. This fresh water flows 

 over the surface of the strait, mixing all the time with the underlying 

 salt water as it flows in a northward direction along the eastern shores. 

 Once these surface waters reach the vicinity of Cape Mudge they turn 

 south and flow along the western shore and finally empty into the Juan 

 de Fuca Strait (Figs. 5 and 6). The passage of this brackish upper zone 

 of water can be marked by the changes in surface salinities at Entrance 

 Island, Cape Mudge, East Point, and finally Race Rocks. The diluting 

 effects of the Fraser River discharge and the degree of mixing with the 

 deeper salt water can be measured by the salinity changes observed at 

 Entrance Island (Fig. 7). A series of oceanographic surveys extended 

 over a period of two years have determined the circulation patterns in 

 Georgia Strait for every month of the year. It is now only necessary 

 to refer to the annual changes in salinity at Entrance Island in order 

 to predict the occurrence and duration of any of the seasonal patterns 

 previously determined by the oceanographic surveys. 



Another application of these daily seawater observations to obsei-v- 

 ing oceanographic conditions is in the "offshore" area. During August 

 of 1950 and 1951 oceanographic surveys were made of the northeast 

 Pacific Ocean extending to 500 miles offshore. In 1950 (Fig. 8) there 

 were three clouds of warm water (60° F) lying in a band parallel to the 

 coast with colder water on either side. In 1951 (Fig. 9) the warm water 

 covered the southwest part of the area surveyed. The surface water 

 temperature increased steadily to seaward and decreased to the north. 

 An examination of the August mean surface water temperatures observed 

 at four seawater sampling stations located on the coast showed that the 

 irregular 1950 "offshore" surface conditions were associated with an ir- 



