TABLE 4.— SUMMARY OF SHORE CENSUSES OF GRAY WHALES IN SOUTHWARD MIGRATION, 



1952-53 TO 1956-57 



1952-53 1953-5-; 1954-55 1955-56 1956-57 



Actual daily count 



Daily extrapolation (bad 

 weather) 



Estimate, all whales passing 

 in day 



Night extrapolation 



Estimate, all whales passing 

 San Diego 



Plus 5 percent for offshore 

 movement 



Final estimate, size of 



California pop\ilation 



1,646 



641 



2,287 

 1,144 



3,431 



172 



3,603 



918 



(M 



{') 

 {') 



(") 



(^) 



(M 



1,839 

 989 



2,828 



1,414 



4,242 



212 

 4,454 



■"" No extrapolations because of incomplete data. 



^ Addition of 293 for 20 percent extrapolation for 2 ho\irs not covered at Point 

 Loma daily. 



AERIAL SURVEYS OF THE WINTERING 

 GROUNDS, 1952-1957 



At one time, the writer believed 

 that air -census methods could be 

 standardized in time and procedure 

 so that land censuses might be dis- 

 pensed with, but his effort to accom- 

 plish this was unsuccessful. Large 

 numbers of breeding whales shift from 

 place to place in a short time, or 

 from season to season, with the result 

 that they cannot be found in exactly 

 the sanne place fronn one visit to the 

 next. 



METHODS 



Areas 



The regular air surveys covered 

 the entire west coast of Baja Cali- 

 fornia and the Gulf coast from Cabo 

 San Lucas to La Paz --also the east 

 side of the Gulf, from Guaymas to 

 Mazatlan (fig. 4). This coverage in- 

 cluded all bays and lagoons in actual 



or potential use by breeding gray 

 whales. Coverage of the east coast 

 of Baja California, from La Paz to 

 the head of the Gulf, was spotty and 

 inconsistent from year to year, but 

 all portions were covered carefully 

 during one year or another. Any lo- 

 cality consistently used by numbers 

 of gray whales would surely have 

 been found. One survey on the coast 

 of the mainland of Mexico went as 

 far south as Puerto Vallarta, 200 

 miles south of Mazatlan, and another 

 to Manzanillo, another 1 25 nniles south, 

 in latitude 18°N. No gray whales were 

 definitely seen south of Reforma. 



Procedure 



The time selected for air surveys 

 was February, after most gray whales 

 had reached the breeding and calving 

 bays and lagoons, and when only a 

 few had departed for the north. Shore 



25 



