encounter them in this area of migrat- 

 ing whales. When the clicks were 

 recorded in Wickaninnish Bay, the 

 gray whales were feeding. Why Gigi 

 emitted clicks when released is un- 

 known. In this case, their function 

 could have been orientation since it 

 is unlikely that she was looking for 

 food so soon after being placed in a 

 new environment. The clicks dis- 

 cussed here are only slightly like 

 those recorded by Asa-Dorian in 1955 

 (see Wenz. 1964). They are not similar 

 to any other reported gray whale 

 sounds. 



Other recent evidence for mysticetes 

 producing click-type sounds has been 

 reported by Beamish and Mitchell 

 (19711. Their recordings in the pres- 

 ence of blue whales included clicks 

 with peak energy in a band from 2 1 

 to 3 1 kHz. 



ACKNOWLEDGMENTS 



We are grateful to Wilburn G. 

 ("Bud") Donahoo for his help at Sea 

 World during the recording session; 

 to William C. Cummings for his 

 advice and assistance in the recordings 

 of Gigi at sea. and to William E. 

 Evans and Fay Wolfson for their 

 suggestions on the manuscript. 



This work was supported by the 

 Naval Undersea Center. Independent 

 Research funding, and the Office of 

 Naval Research. Oceanic Biology 

 Branch. Grant No. NR 104-123. 



LITERATURE CITED 



Asa-Donan, P. V., and P. J. Perkins. 1967. 

 Ttie controversial production of sound 

 by the California gray whale, Eschricluiiu 

 gihhosus. Nor. Hvalfangst-Tid. (Norwe- 

 gian Whaling Gazette) 56:74-77. 



Beamish, P., and E. Mitchell. 1971. Ultra- 

 sonic sounds recorded in the presence of 

 a blue whale, Bakwrniplera tnit^cultis. 

 Deep-Sea Res. 18:803-809. 



Cummings, W. C, P. O. Thompson, and R. 

 Cook. 1968. Underwater sounds of mi- 

 grating gray whales, Eschruhtius kUiucus 

 (Cope). J. Acoust.Soc. Am.44:1278-1281. 



Eberhardt, R. L., and W. E. Evans. 1962. 

 Sound activity of the California gray 

 whale, Eschrichnu.s glaiiciis. J. Aud. Eng. 

 Soc. 10:324-328. 



Gales, R. S. 1966. Pickup, analysis, and 

 interpretation of underwater acoustic data. 

 Ill K. S. Norris (editor). Whales, dolphins, 

 and porpoises, p. 435-444. Univ. Calif. 

 Press, Berkeley and Los Angeles. 



Hubbs, C. L. 1966. Comments. In K. S. 

 Norris (editor). Whales, dolphins, and 

 porpoises, p. 444. Univ. Calif. Press, 

 Berkeley and I os Angeles, 



Painter, D. W., II. 1963. Ambient noise 

 in a coastal lagoon. J. Acoust. Soc. Am. 

 35:I458-1459(L). 



Poulter, T, C. 1968. Vocalization of the 

 gray whales in Laguna Ojo de Liebre 

 (Scammon's Lagoon) Baja California, 

 Mexico. Nor Hvalfangst-Tid. (Norwegian 

 Whaling Gazette) 57:53-62. 



Rasmussen, R. A., and N. E. Head. 1965. 

 The quiel gray whale ( E.schnchinis glaiicu.s). 

 Deep-Sea Res. 12:869-877. 



Rice. I). W., and A. A. Wolman. 1971. 

 The life history and ecology of the gray 

 whale {Escliricluiiis robuxius). Spec. 

 Publ. 3. Am. Soc. Mammal., 142 p. 



Wenz, G. M. 1964. Curious noises and 

 the sonic environment in (he ocean. In 

 W. N. Tavolga (editor). Marine bio- 

 acoustics, p. 101-123. Pergamon Press. 

 New York. 



MFR Paper 1054. From Marine Fisheries Review, Vol. 

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

 numbers, are available from D83. Technical Information 

 Division, Environmental Science Information Center, 

 NCAA, Washington. DC 20235. 



MFR PAPER 1055 



Aerial Observations of Migrating Gray 

 Whales, Eschrichtius robustus, off 

 Southern California, 1969-72 



J.S. LEATHERWOOD 



ABSTRACT 



Miiiratini; iiray hIuiIcs were observed from lielicopler und fi.\ed-\\ini; (linnifl 

 from central Ccdifoniici .soiilh lo Cedros mid Giuididiipe Islunds. Baja California. 

 Me.xico. Willi ihe primary .\ii;/ilini.; effort off southern California. Peak nundiers 

 were observed off soiit/iern California in January for tlie southward iniiiration 

 and in Marcli for tite iiortliward inii;ratioii. Individuals were observed with the 

 same relative frequency 80-160 km offslun-e as they were within 80 km of 

 shore. Cows witli calves were seen from February through May. primarily 

 inshore, and tended lo be alone or with other cou s with calves. Yearling whales 

 were seen insliore from February through April and also tended to be solitcuy 

 or with other yearlings. Average speed of movement for lunthward migrants 

 was 2.8 knilhonr. 



Results of aerial surveys compare favorably with published summaries of 

 the liming of migration based on sliore and ship samples and support the \'alue 

 oj aerial surveys us u tool in cetacean population studies. 



INTRODUCTION 



Since shortly after its population 

 began to recover from a second near- 

 e.xtermination by man in the 1920's 

 and I930's (Gilmore, 1955), the Cali- 

 fornia gray whale, Esclirichtius ro- 

 bustus, has been the subject of more 

 public interest and more scientific 

 research than perhaps any other spe- 

 cies of large whale. Because of their 



spectacular nature and proximity to 

 shore along much of the route, the 

 migrations of the species have been 

 rather exhaustively described by Scam- 

 mon (1874), Hubbs (1959), Gilmore 

 (1960a and 1960b), Rice (1961), Pike 

 (19621. Hubbs and Hubbs (1967). 

 Adams ( 1968). and Rice and Wolman 

 (1971). Observations from shore sta- 

 tions (primarily at Point Loma in 



45 



