318 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



they were consistently higher, thence downward, 

 with a maximum difference of 5.3° between the 

 2 series of readings at 120 meters, which was the 

 deepest level at which the temperature was 

 recorded in 1953. In the underlying strata this 

 contrast is of the order to be expected from the 

 difference between the dates when the observa- 

 tions were taken in the 2 years. Furthermore, it 

 may be no greater than can be explained on this 

 basis, especially in view of the difference in the 

 positions, for the 1953 station was about 21' miles 

 farther out along the channel than the 1914 

 station, i. e., that much nearer the reservoir from 

 which deep water enters the channel from the 

 continental slope. Neither is the lower surface 

 temperature for 1953 a safe index to the year-to- 

 year fluctuation, for the surface had no doubt 

 cooled 2° to 3° by the date of observation, whereas 

 in 1914 the temperature was recorded when the 

 surface was nearing its warmest for the year. 

 Unfortunately, we have no salinity information 

 for the 1953 station, which is the only reliable 

 index to the amount of water from the continental 

 slope that is entering the Gulf on any given 

 occasion, or that had recently done so. 



Table 21. — Waler temperatures in the eastern channel 

 between Georges Bank and Browns Bank in 1914 o,nd 

 in 1953 



[Area L, flg. 16. Temperature in °F.] 



' Scaled from vertical graph for station. 



The Albatross III established only one station 

 on Browns Bank inside the 50-fathom contour 

 (area L, fig. 12) during her August-September 

 1953 cruises and recorded a bottom temperature 

 of 50.9° F. on September 12 at 90 meters. This 

 is slightly higher than the bottom temperatures 

 reported by McLellan (1954, p. 410, fig. 4; p. 

 412, fig. 6) of about 42.8° to about 48° August 

 16-27, 1950, and of about 42.8° to slightly above 

 48° August 14-September 5, 1952. A bottom 

 reading by the Grampus, July 24, 1914, of 47.3° 

 is too close to McLellan 's to suggest that any 

 long-term alteration of significance had taken 

 place in the summer temperature of the bottom 



water on Browns Bank during the intervening 

 36 years. 



The comparison between temperature condi- 

 tions in the Gulf of Maine in August and early 

 September of 1953 and in the earlier summers of 

 record may be summed up as follows: 



The entire water column down to 150 meters 

 was warmer on the western side of the Gulf and 

 around the northern periphery including the 

 lower Bay of Fundy in 1953 than in the period 

 1912-26. This upward shift in temperature in 

 1953 as compared with 1922 amounted to 5° to 6°, 

 at least, in Cape Cod Bay; to some 2° to 4.5° 

 from surface to 150 meters off Cape Ann; to 1.5° 

 to 3° from surface to 40 to 60 meters near Mount 

 Desert Island; and to about 2° to 2.5° in the 

 lower part of the Bay of Fundy at depths of 25 

 meters and greater. The upward shift in temper- 

 atures may have been as great in the eastern part 

 of Georges Bank as in the western side of the 

 Gulf, though differences in the dates when these 

 observations were taken prevent definite com- 

 parison. Available data are at least compatible, 

 with somewhat higher summer temperatures in 

 1953 than in previous summers on the western 

 part of Georges Bank (p. 317). 



In the central and northeastern parts of the 

 basin of the Gulf, at depths greater than 40 

 meters, the temperature was about as much 

 warmer in 1953, compared to the period 1912-26, 

 as it was farther to the north and west. We have 

 no information to indicate any definite shift in 

 temperature, either upward or downward, in the 

 upper 10 meters or so, if allowance is made for 

 differences in the location of the stations where 

 the readings were taken and in the season and 

 the stage of the tide when the observations were 

 made in the different years. Thus, the surface 

 was warmest in 1914 both in the central part of 

 the basin and in the eastern side near the Nova 

 Scotian slope, but warmest in 1926 in the north- 

 eastern part near Mount Desert Rock. Readings 

 taken August 1953 in the extreme southeastern 

 part of the basin near the rising slope of Georges 

 Bank were intermediate between those taken 

 July 1914 and August 1926, at all depths from 

 the surface down to 260 meters. Evidently, the 

 effects on water temperatures of differences from 

 year to year in air temperatures are masked in 

 this region by the control exerted by warming 

 by water from the continental slope, on the one 



