666 



BULLETIN OF THE BUEEATJ OF FISHERIES 



does not fall quite as low in winter, being farther ofTshore. The date when the tem- 

 perature rises to its maximum for the year is also about the same here as in the bay — 

 mid-August for the surface, late August or early September for the 20-meter level — 

 but in 1920 this part of the basin was not coldest until about the last week in March, 

 whereas the surface in the neighborhood of Gloucester had begun to warm by the 

 end of February, a difference corresponding to the difference in location (p. 694). 

 Vernal warming is also generally parallel at these two locations down to the 40-meter 

 level; but it can readily be appreciated that any upwelling of the much colder bot- 

 tom water at any time from June to October would interrupt the orderly progression 



Nov Dec. Jan /vi>. /^crrch /i/'/' /ytpy June Ju/y Auff. Sept Oct 



Fig. 88.— Composite diagram of tbe normal seasonal variations of temperature near Mount Desert Island, at the surface, 

 20 meters, and 40 meters, from data for the years 1915, 1920, 1921, and 1923. The curves are smoothed 



of the 40-meter temperature, and it is probable that the very low 40-meter reading 

 recorded off Cape Cod for August 22, 1914 (station 10264, 5.75°) is to be accounted 

 for on this basis. Lacking data for late September or early October, I can not defi- 

 nitely state whether the 40-met.er level of this side of the basin warms to its annual 

 maximum at about the same date as in Massachusetts Bay (September) . 



The amplitude of the seasonal variation in temperature is nearly the same in the 

 superficial stratum of the basin off the mouth of Massachusetts Bay as within the 

 latter — i. e., a range of about 17° to 19° from summer to winter at the surface, about 

 10° to 11° at 20 meters, and about 7° to 8° at 40 meters. Unfortunately the only 



