680 
BULLETIN OF THE BUREAU OF FISHERIES 
determined were taken from the works of Schott (1928 and 1935), Uda and Okamoto 
(1930), and Uda (1931). 
The isohalines of 33 and 34 parts per thousand describe the mean annual salinities 
of the surface waters at the southern boundaries in the distribution of the salmon 
along the coasts of Korea and Japan. Owing to the direct contact of warm currents of 
high salinity with cold currents of low salinity, and the continuous shifting of these 
currents off the eastern coast of Honshu Island, the isohaline of 34 parts per thousand 
is not confined to any one district but shifts about over a broad area. Hence, the sal- 
mon frequenting the waters in this area may at times be subjected to surface salinities 
as high as 35 and as low as 33 parts per thousand. 
The southern distributional limits of the salmon on the North American continent 
fall within an area whose coastal waters are characterized by mean surface salinities 
from 33 to 34 parts per thousand. In the northern range of the salmon the mean 
salinities of the surface waters do not exceed 30 parts per thousand. It is, therefore, 
quite possible that the salmon orient themselves in the open ocean to surface waters of 
salinities ranging from 30 to 35 parts per thousand. 
The analysis of the marine habitats thus far has been confined mainly to the deter- 
mination of the ranges in certain physical and chemical properties of the waters in the 
North Pacific Ocean within the limits of the native distribution of the salmon. Briefly, 
it was found that the occurrence of the salmon is associated with the presence of ocean 
currents bearing waters of low temperature and salinity. The mean surface tempera- 
tures during the spawning migration period of the salmon ranged from 0° to 20° C. 
The mean annual temperatures at 200 meters ranged from slightly below 0° to 10° 
C. and the mean annual surface salinities varied from 30 to 35 parts per thousand. 
Since the salmon frequent the ocean waters of these temperatures and salinities, it 
may be assumed that they are tolerant to them. In this analysis, however, it has 
not been possible to definitely determine if temperatures and salinities outside these 
ranges are also tolerated by the salmon or form definite limiting factors governing their 
survival. The further analysis of this relationship may be found in a similar study of 
the marine waters in the foreign regions where the salmon have been transplanted. In 
other words, if the foreign marine waters in which the transplantations have survived 
have physical and chemical properties similar to those in the native distribution of 
the salmon and if the foreign waters where the transplantations have failed have 
properties unlike those in the native distribution, fresh-water conditions being favor- 
able to survival, then it is logical to assume that temperature and salinity values 
beyond the ranges of the native distribution may form limiting factors to the marine 
survival of the species. 
SOUTH PACIFIC REGION 
In discussing the foreign distribution of the Pacific salmon in this region it was 
pointed out that transplantations were made in Hawaii, Chile, New Zealand, Tas- 
mania, and Australia. Natural sea-run populations developed from the transplanta- 
tions in New Zealand and Chile but failed to develop from those planted in Hawaii, 
Tasmania, and Australia. 
New Zealand is composed of two large islands, known as North Island and South 
Island. Some of the streams on each island were stocked with chinook salmon from 
the Sacramento River, Calif., but only those on South Island have developed natural 
