again used. The flight was made in 

 good weather and provided excellent 

 coverage, but the number of whales 

 was disappointingly small. 



SUMMARY OF AERIAL SURVEYS 



Because the air -survey method in- 

 troduced many variable factors, and 

 information needed to apply corrections 

 was not available, it is unwise to 

 estimate the size of the total popula- 

 tion on air -survey data. However, an 

 air survey is the only way to deter- 

 mine the extent of breeding grounds, 

 the relative use of areas as calving 

 grounds, and changes from year to 

 year. 



The breeding areas may, as a result 

 of the aerial surveys, be ranked as 

 follows : 



Vizcaino -Scammon area . --This is 

 the most important of the winter calv- 

 ing areas. During the five years of 

 the surveys, it might have held numbers 

 of whales varying from 1,500 to 2,000, 

 or about half the total population. 



Magdalena area . --This is the second 

 most important calving ground. Per- 

 haps 1,000 to 1,500 whales, or about 



one-third the total population, visited 

 the area during each year of the 5- 

 year period of the surveys. 



San Ignacio area . --This is the third 

 most important spot for calving and 

 mating, with perhaps 500 whales, or 

 between one-teighth and one -sixth the 

 total winter population. 



Reforma area . --The highest count 

 made at one timie here was 18 adults 

 and 12 calves. 



Yavaros area . --Evidently only small 

 numbers of whales used the Yavaros 

 area. The highest count was 10 adults 

 and 7 calves. 



The area available for calving and 

 mating may be the most critical factor 

 in determining eventual size of the 

 population. Reduction of this area by 

 natural (geological) events or by man 

 may have a pronounced effect in lower- 

 ing the population ceiling. Man -modi- 

 fied or man -disturbed lagoons and bays 

 which should be carefully watched are 

 Bahia San Quintin, Laguna Guerrero 

 Negro, Bahia Magdalena, Bahia Re- 

 forma, and the Yavaros area. Continued 

 studies of these areas will help to 

 evaluate the relationship between gray 

 whales and man (see table 5). 



LITERATURE CITED 



ANDREWS, R. C. 



1914. The California gray whale 

 (Rhachianectes glaucus). Memoirs 

 of the American Museum of 

 Natural History, l(5):227-287. 



ANTHONY, A. W. 



1921. The California gray whale 

 on the coast of southern Cali- 

 fornia. Journal of Mammalogy, 

 2(3):174. 



BERDEGUE, J. 



1956. Ultimo censo de la ballena 

 gris, Rhachianectea glaucus (Cope) 

 en aguas de Baja California. 

 Ciencia, l6(4-6):99-109. 



CEDERLUND, B. A. 



1939. A subfossil gray whale dis- 

 covered in Sweden in 1859. 

 Zoologiska Bidrag fr&n Uppsala, 

 18:269-286. 



COPE, E. D. 



1868. [Remarks on Cetacea at 

 meeting of 23 June.] Proceed- 

 ings, Academy of Natural 

 Sciences of Philadelphia, 

 20:159-160. 



1869. Systemiatic synopsis of the 

 species of the cetaceans of the 

 west coast of North America. 

 Proceedings, Academy of Natu- 

 ral Sciences of Philadelphia, 

 21:14-32. 



DANIELSEN, E. F., W. V. BURT, 

 AND M. RATTRAY 

 1957. Intensity and frequency of se- 

 vere storms in the Gulf of 

 Alaska. Transactions, Ameri- 

 can Geophysical Union, 38(1):44- 

 49. 



29 



