CLIMATE AND THE DISTRIBUTION OF MARINE ANIMALS 



317 



Table 17. — Water temperatures in southeastern part of 

 basin in 195S and in earlier years 



< Scaled from vertical graph (or this station. 

 J Deepest reading was at 241 meters. 



Any continued alteration in temperatures for 

 the summer-autumn period on Georges Bank is of 

 special interest, because of the productivity of 

 the Bank as a fishing ground. Unfortunately, the 

 records are not clear in this respect, because the 

 readings for 1914 and 1926 were taken so much 

 earlier in the season than were those for 1953 that 

 somewhat lower values at the surface and higher 

 temperatures below the surface were to be ex- 

 pected in 1953 than in the earlier summers, quite 

 apart from any year-to-year fluctuation. This 

 seasonal progression is illustrated by the tempera- 

 tures taken on the eastern end of the Bank (area 

 H, fig. 16; table 18) July 23, 1914, August 13, 

 1926, and September 13, 1953. But the mean 

 temperature for the water column as a whole — 

 nearly 8° lower in mid-August of 1926 than in 

 mid-September of 1953 — at least suggests that 

 the summer of 1953 not only was warmer on this 

 part of the Bank, but that it was as much warmer 

 as were the western and northern parts of the Gulf. 



Table 18. — Water temperatures on eastern part of Georges 

 Bank in September 195S and in earlier years 



[Area H, fig. 16. Temperature in "F.) 



' Scaled from graph for this station: readings at 30 meters and at 55 meters. 

 ^Scaled from graph for this station; readings at 40 meters and at 70 meters. 



On the western part of Georges Bank, move- 

 ments of the waters are so complex that wide 

 differences in temperature within short distances, 

 even on the same day, are not unusual. Readings 

 at a pair of stations about 10 miles apart on the 

 northwestern end of the Bank (area J, fig. 16; 



table 19) September 5, 1953, and at a second pair 

 about 17 miles apart, on the southwestern end 

 (area K), September 3^, afford a striking example 

 of this regional irregularity'. Under such cir- 

 cumstances the danger is obvious of mistaking 

 regional or short-term variations for 3'ear-to-year 

 differences, when temperatures for diflFerent sum- 

 mers are compared. The present case is further 

 complicated by the seasonal rise in temperature 

 to be expected during the 5- to 6-week period 

 between the dates of observation for 1914 (July 

 20), for 1916 (July 23), and for 1953 (September 

 3-5). Perhaps the most that can be said is that 

 mean temperatures, which were some 6° higher 

 in the upper 20 meters and some 4° higher at 40 

 to 50 meters in early September of 1953 than they 

 were in late July of 1914 and of 1916 (table 20) 

 on the western part of the Bank (areas J and K 

 combined, fig. 16), are at least compatible with 

 the somewhat higher temperatures that prevailed 

 in the inner parts of the Gulf in 1953, as appears 

 more clearly from the serial observations pre- 

 viously discussed (p. 306). 



Table 19.^ — Regional variation in water temperatures on 

 northwestern and southwestern parts of Georges Bank 



' Deepest reading was at 67 meters. 



Table 20.^ — Water temperatures on western part of Georges 

 Bank in 1953 and in earlier years 



In the eastern channel between Georges and 

 Browns Banks (area L, fig. 16; table 21), the 

 readings were about 2° lower at the surface for 

 September 12, 1953, than for July 24, 1914, but 



