all greater than 30 feet in length. 

 Furthermore, in all cases the gray 

 whales have appeared to be passive 

 participants in the interaction. 



LITERATURE CITED 



Andrews. R. C 1914. Monographs of the 

 Pacific Cclacea. I. The California gray 

 whale {Rhiichuinecifs gUiiicus Cope). lis 

 history, habits, external anatomy, osteology 

 and relationship. Mem. Am. Mus. Nat. 

 Hist. (New Ser.) 1:227-287. 



Baldridge, A. 1972. Killer whales attack 

 and eat a gray whale. J. Mammal. 53:898- 

 900. 



Burrage, B. R. 1964. An observation re- 

 garding gray whales and killer whales. 

 Trans. Kansas Acad. Sci. 67:5.'^0-5? 1. 



Caldwell, D. K., and M. C. Caldwell. 196.3. 

 Surf-riding by the California gray whale. 

 Bull. South. Calif. Acad. Sci. 62(2):99. 



Evans, W. E. 1974. Telemetering of tem- 

 perature and depth data from a free rang- 

 ing yearling California gray whale, £.«7i- 

 richtnis rohiisiiis. Mar, Fish. Rev. 36(4): 

 52-58. 



Evans. W. E., and J. J. Dreher. 1962. Ob- 

 servations on scouting behavior and the 

 associated sound production by the Pacific 

 bottlenosed porpoise (Tiir.siopi i;illi Dall). 

 Bull. South. Calif. Acad. Sci. 61:217-226. 



Gilniore, R, M. 1961. The story of the gray 

 whale, 2nd ed. Privately published, San 

 Diego, 16 p. 



Leatherwood, J. S. 1974. Aerial observa- 

 tions of migrating gray whales, Eschrich- 

 liiis robustus, off southern California ( 1969- 

 1972). Mar. Fish. Rev. 36(4):45-49. 



Morejohn, G. V. 1968. A killer whale- 

 gray whale encounter. J. Mammal. 49: 

 327-328. 



Scammon, C. M. 1874. The marine mam- 

 mals of the North-western coast of North 

 America. John H. Carmany and Co., 

 San Francisco, 3 19 p. 



MFR Paper 1056. From Marine Fisheries Review, Vol. 

 36. No. 4, April 1974. Copies of this paper, in limited 

 numbers, are available from D83. Tecfinical Information 

 Division. Environmental Science Information Center, 

 NOAA. Wasfiington. DC 20235. 



MFR PAPER 1057 



Aerial Observations of Gray 

 Whales During 1973 



Radio communications with shore 

 observers permitted coordination of 

 observational efforts. Time, location, 

 numbers of whales, and behavior ob- 

 servations were noted for the sight- 

 ings and photographs were attempted 

 on occasion. 



122* OO'W 



I 



Figure 1. — The area off California observed for 

 gray whales. 15-23 January 1973. 



PAUL N. SUND antd JOHN L. O'CONNOR 



During their annual southward 

 migration California gray whales. 

 Eschrichliiis rohiisnis. were observed 

 between Monterey Bay and Point 

 Sur. Calif. (Figure 1) from an air- 

 craft during the period 15-23 January 

 1973. An aerial survey was initiated 

 in response to recommendations of 

 the Joint Naval Undersea Center — 

 National Marine Fisheries Service 

 (NMFS). Southwest Fisheries Center 

 Gray Whale Workshop (held in La 

 Jolla. California in August 1972). that 

 the accuracy of the annual NMFS 

 shore census taken near Yankee Point 

 be checked. The survey was designed 

 to compare shore observers' estimates 

 of numbers with those of aerial ob- 

 servers; to test the estimate that 95 

 percent of the gray whales migrating 



by Yankee Point pass within 1.9 km 

 (1.2 miles) of the shore (Rice and 

 Wolinan. 1971); and to provide ob- 

 servations of gray whale behavior and 

 associations with other marine mam- 

 mal species. The utility of aerial sur- 

 veys in cetacean research has been 

 demonstrated by Levenson (1968) and 

 Leatherwood ( 1974a. b). This paper 

 reports on simultaneous shore and 

 aircraft observations and discusses 

 the problems inherent in each method. 



METHODS 



Five flights, totaling 13.6 hours, 

 were made between Monterey Bay 

 and Point Sur. Calif. (Figure I) in a 

 Cessna 172 flown by a professional 

 spotter-pilot at altitudes ranging from 

 150 m (500 ft) to 900 m (3,000 ft). 



RESULTS AND CONCLUSIONS 



From the aerial observations made 

 in the sector scanned by shore obser- 

 vers, the following points were deter- 

 mined: Of 24 paired observations 

 (individuals or groups observed by 

 both air and ground personnel), ini- 

 tial visual contact was made by a 

 ground observer in eight instances and 

 by an airborne observer in ten in- 

 stances. Hence, ground and aircraft 

 observers apparently were equally 

 adept at initially sighting whales. Of 

 the 24 paired sightings, the aerial 

 observers were able to correct the 



Paul N. Sund is with the Pacific 

 Environmental Group, National 

 Marine Fisheries Service, 

 NOAA, Monterey, CA 93940. 

 John L. O'Connor, P.O. Box 

 1942, Newport Beach, C A 92660. 



51 



