Georges Bank—Spring.—Adjusted spring bottom- 
water temperatures on Georges Bank (Fig. 10) are 
characterized by a low in 1971 of 3.8°C, followed by 
rather large annual increases to a peak of 6.3°C in 1974, 
and then a sharp decline of 1.9°C in 1975. The 8-yr 
mean of 5.0°C is 1°C lower than that reported by 
Karaulovsky and Sigaev (see footnote 2) for 1962-72, but 
their coverage included waters deeper than 100 m which 
probably accounts for much of the difference. Data from 
Schopf (1967) indicate a mean Georges Bank bottom- 
water temperature in the spring of approximately 6°C in 
1955, 4.5°C in 1956, 3°C in 1965, and 3.5°C in 1966. 
Georges Bank is usually dominated by the 4°-6°C TCI 
in the spring which in 1969 accounted for 90% of the area 
within the 100-m isobath (Fig. 11). The minimum (1971) 
and maximum (1974) observed means were influenced by 
a replacement of the 4°-6°C TCI with 2°-4°C and 6°-8°C 
water, respectively. Since the Bank waters are well 
\ 
\\ 
\ 
\ 
\ 
\ 
\ 
\ 
Observed 
BOTTOM -WATER TEMP °C 
61) 
Spring - 
GEORGES BANK 
IS6S8 MOS WOM. ale 25m a Seer dae, 
Figure 10.—Observed and adjusted mean bottom-water tempera- 
tures on Georges Bank during the spring, 1968-75. 
7 
6 
5 
4 
Fa 
6 § 
b a 
2 
a ae 
oO 
ns <q 
a 7 Ts 
a 6 6 s 
- 
eats 
a) 
TA it 
6 6 
5 5 
4 4 
Zea G8 NON N24 25 45698 10F2 514 
Wel TECH 
Figure 11.—Percentages of temperature-class intervals (TCI’s) on 
Georges Bank during the spring, 1968-75. (Dotted circles represent 
the observed mean bottom-water temperatures.) 
mixed vertically in the spring, these changes in TCI per- 
centages in 1971 and 1974 reflect broad-scale differences 
from average habitat conditions. 
Subareas of Georges Bank—Spring.—Unlike the 
Gulf of Maine, year-to-year changes in spring tempera- 
tures were similar in all the subareas of Georges Bank, 
which emphasizes the homogeneity of these shoal waters 
(Fig. 12). Central Georges Bank, which has the highest 
proportion of shoal water, was usually the coldest of the 
three subareas and reached a minimum of 4.0°C in 1971. 
Western and Eastern Georges Bank had very similar 
mean temperatures except in 1968 when Eastern Georges 
Bank reached the time-series minimum of 3.6°C for all 
subareas and had an anomaly of —1.7°C (Table 3). 
Subarea TCI’s for spring are shown in Figure 13. It is 
interesting to note that the warm years of 1973 and 1975 
(observed means) were substantially influenced by water 
>8°C in all three subareas, but that the warmest year, 
1974, had none of this water. The rather low observed 
mean for the entire Bank in 1968 was mainly the result of 
a 2°-4°C TCI covering 75% of the eastern subarea; water 
BOTTOM -WATER TEMP °C 
4 iN Yael 
} 
Eastern Georges 
(es) 
Spring, Subareas — GEORGES BANK 
1963 69 70 71 ie 73 74 75 
Figure 12.—Adjusted mean bottom-water temperatures on Georges 
Bank by subareas during the spring, 1968-75. 
Table 3.—Mean bottom-water temperatures and anomalies for Georges Bank, spring 1968-75. 
Adjusted values are shown in parentheses. 
Subarea Mean 1968 1969 1970 1971 1972 1973 1974 1975 
Western 5e3 = Bi! =i. 
(5.3) (-1.6) (+ .2) (- 
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Central 
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