( rrand Banks. At that time, although no iceberg threat yet existed, it was 

 deemed expedient to commence the International Ice Patrol and, ac- 

 cordingly, this was done on 5 March. 



The first icebergs to be reported for the year were by Belle Isle Radio 

 on 2(> February. A more southward advance, however, was indicated 

 when USCGC Humboldt sighted three Large bergs on I .March near Lat. 

 51°31' X. longitude 48°30' W. 



Aerial reconnaissance served as the primary means of ice observation 

 throughout March. The statistics for aircraft operations this month and 

 the remainder of the season are presented in a later section. 



Field ice over the Grand Hanks reached its greatest southward extent 

 for the year during the middle of March when it covered the entire 

 northern slope of the Banks. These conditions are illustrated by figure 10 

 and represent conditions considered to be about average for the Grand 

 Banks regions. 



Icebergs made their appearance on the Banks during the last week in 

 March which is a relatively late date for this occurrence. But by the 

 middle of April, however, increasing numbers of bergs arriving and drift- 

 ing south along the eastern slope of the Grand Banks made it apparent 

 that a severe year was at hand. The establishment of a surface patrol at 

 the southern limits of the icebergs was indicated advisable. The USCGC 

 Acushnet was ordered to sea and assumed the duties of Ice Patrol Vessel 

 on 20 April in position 42°06' N. 49°37' W. when that cutter began a 

 northward search along the eastern slope of the Banks. Prevailing fog 

 during this period prohibited aerial observation. Thereafter, a ship patrol 

 was maintained until 14 July. Statistics for patrol vessel operations are 

 presented in a following section dealing with Surface Ice Patrol. 



The oceanographic program of the international Ice Patrol was com- 

 menced on 4 April when the USCGC Evergreen sailed on the first of four 

 surveys during the season to map the ocean currents affecting berg drift 

 into the North Atlantic Ocean. A detailed discussion of this work is pre- 

 sented in the last section of this Bulletin. The chart of ocean currents 

 produced by each survey is a valuable instrument for the evaluation 

 of iceberg reports and the prediction of berg drifts. 



The scheduled southward shift of shipping lanes from Track "C" to 

 Track "B" on 1 1 April occurred none too soon. Icebergs were sighted on 

 Track "C" on 13 April and remained until 1 July, the very day it once 

 again became effective. 



Field ice in the Cabot Strait and Gulf of St. Lawrence broke up during 

 April. Traffic into the Gulf had commenced the beginning of April with 

 the help of Canadian icebreakers and ice advisories by the Halifax Ice 

 Forecasting Central and by the end of the month the main shipping track 

 was free of ice and in full use. This area had recorded a particularly severe 

 and prolonged season. Especially hard hit was the Newfoundland west 

 coast where ice blocked the ports of Stephen ville and Corner Brook until 

 May. Large United States and Canadian icebreakers attempting to convoy 



