576 BULLETIN OF THE BUREAU OP FISHEEIES 



12 (station 10276) to 7.8° on June 14 (station 10287) off Penobscot Bay; the 40- 

 meter level from 4.2° to about 5.8°, while the courses of the curves suggest that no 

 appreciable change in the temperature of the water is to be expected at or below 80 

 meters off this part of the coast during the month of June. 



In the immediate vicinity of Mount Desert Island the surface temperature rose 

 by about 1° from May 10 to 11 (stations 10274 and 10275, 4.2° and 4.4°) to 

 June 10 to 11 (stations 10283 and 10284, both 5.4°); but four days later surface 

 readings of 7.5° to 8° were had at three stations (10285 to 10287) a few miles to the 

 westward. The graphs (fig. 7) for these stations, as compared with May 10 (station 

 10274), show that the whole column, down to the bottom in 80 meters, warmed at 

 a nearly equal rate there up to June 10, instead of most rapidly at the surface, as 

 happens off Penobscot Bay and in the Massachusetts Bay region, no doubt 

 because of the stronger tidal currents to the east than to the west of Penobscot Bay 

 (p. 678). 



Near Mount Desert Island this vertical stu-ring is sufficiently active to bring 

 the whole column of water uniformly under the effect of the sun's rays during the 

 early spring, resulting in the uniform rate of warming from surface to bottom just 

 noted. During June, however, the surface receives heat so rapidly there, coupled 

 with a corresponding freshening (p. 747), that the column is stabilized vertically, 

 though the deeper layers are never so insulated here as in the less actively stirred 

 waters to the west of Penobscot Bay and to the south of Cape EUzabeth. 



In 1915 this establishment of stability in the Mount Desert region evidently 

 fell between June 10 and June 15, because the surface warmed more rapidly there 

 between these two dates (a change of about 2°) than it had during the preceding 

 month, though the 30-meter and deeper temperatures rose by only about 0.2° 

 meantime. 



Data are not available for a general survey of the temperature of the Bay of 

 Fundy for the month of June, but very considerable local differences in the rate of 

 vernal warning are to be expected there during the early summer to correspond with 

 regional differences in the activity with which the water is stirred by the violent 

 tidal currents. The Grand Manan Channel stands at the one extreme, with the whole 

 column of water warming uniformly, or nearly so, through June down to 100 meters, 

 and correspondingly slowly at all depths. Thus, on June 4, 1915, the whole column 

 of water in the western end of the channel abreast the north end of Grand Manan 

 (station 10281; 80 meters) was about 4.5° in temperature, pointing to a rise of about 

 2° at all levels from the minimum of the preceding winter, and the channel continues 

 homogeneous in temperature from surface to bottom into August (p. 599) . 



In the central parts of the Bay of Fundy, however, vernal warming essentiallj' 

 parallels the accoimt just given for the Mount Desert region, with a similar seasonal 

 relationship between successive monthly curves (fig. 40) constructed from Mavor's 

 (1923 ; Prince station 3) records for the spring of 1917, though the actual temperatures 

 differ somewhat at the two localities. Thus, this Fundy station warmed from 2.96° to 

 8.18° at the surface between May 4 and June 15; from 2.01° to 4.13° at 50 meters; 

 from 1.87° to 3.92° at the 100-meter level; and from 1.75° to 2.08° at 150 meters; 



