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BULLETIN OF THE BUREAU OF FISHERIES 
VARIATION OF BOTTOM TEMPERATURE ACROSS BAY 
The temperature of the bottom water depends upon several factors, the most im- 
portant of which are depth, presence of ice, inflow of water from the ocean, seasonal 
changes, and to some extent sudden changes in air temperatures. Our records 
show that on the summer cruises the coldest bottom water was found along the deep- 
water channel G, A, H, J, L, R, S, X, and Y and that on the winter cruises the bottom 
water of this channel was the warmest. Locally, at times during the autumn or 
winter and occasionally during the spring the temperature relations just mentioned 
were not so marked. The bottom temperatures along a line across the bay cutting 
the deep channel may show an approach to uniformity, notwithstanding large differ- 
ences in depths. As examples, in the spring, during the March cruise, 1916, the 
bottom temperatures for D (5.5 meters), C (11 meters), B (12 meters), and A (40 
meters) were 3.3° C., 3.3° C., 3.3° C., and 3.4° C., respectively, while in January, 
1916, for the same areas the temperatures were 3.3° C., 3.9° C., 3.8° C., and 4.3° C. 
During the summer cruises, July, 1916, the bottom temperatures for D (6 meters), 
C (10 meters), B (12 meters), and A (42 meters) were 25.5° C., 24.9° C., 24.4° C., 
and 24.2° C. 
VERTICAL DISTRIBUTION OF TEMPERATURE 
The vertical distribution of temperature depends on many factors among which 
are: Seasonal, diurnal, and sudden local changes in air temperature sometimes 
accompanied by vertical circulation; strength and direction of the wind; relative 
thickness of fresh-water layers coming from the rivers and the more saline layers 
derived from the ocean; the relative temperatures of the fresh water and saline water 
layers; the cooling effect of the rain on both air and surface water (Kriimmel, 1911); 
the decrease in temperature due to ice floes; and the depth of the water. 
As might be expected, the greatest range in temperature from surface to bottom 
was found in the deep channel. Area G, at the mouth, showed the most extensive 
range — for example, in August, 1920, surface 27.0° C., bottom (23.6 meters) 15.5° C.; 
and in June, 1916, surface 20.5 ° C., bottom (22 meters) 10.7° C., a difference of 11.5° 
C. and 9.8° C., respectively. 
An examination of the vertical temperature series shows that sudden breaks in 
temperature occur in the region of 10 to 20 meter depths. These changes are most 
clearly marked in the deeper parts of the bay and are most commonly observed when 
the water is stable or “harder” as Sandstrom (1919) describes it. Water in this 
condition shows layers of increasing density and usually increasing salinity passing 
from the surface to the bottom, and such a condition is characteristic of the warmer 
months of the year. A rather common summer condition for temperature, at least 
during the warmer part of the day, is that obersved at area R during June, 1921 
(surface 20.0° C., 10 meters 20.0° C., 20 meters 15.5° C., 30 meters 15.3° C., 40 meters 
15.3° C., 47.6 meters 15.1° C.). The layer showing the sudden decrease in tempera- 
ture between 10 and 20 meters, which is evident in the series, is what is called the 
“ Sprungschicht ” by Richter (1891) and Kriimmel (1911), “discontinuity layer” by 
Murray and Hjort (1912), “ thermocline ” by Birge (1898), and “transition zone” 
by Whippel (1914). This decline in temperature corresponds very definitely in depth 
with an increase in salinity. (Surface 11.20, 10 meters 11.68, 20 meters 19.42, 30 
meters 19.66, 40 meters 19.80, 47.6 meters 19.78.) A similar relation between tem- 
peratures is often seen during the warmer months but frequently the correspondence 
in depth with the salinity increase is not so definite as in the case mentioned. Indeed, 
there is evidence indicating that, the discontinuity in temperature may be disturbed 
