SUMMARY 



Gray v/hsil e s, Eschrichtius gibhosus 

 (Erxleben) 1777, were originally three 

 isolated stocks, termed the Atlantic, 

 California, and Korean populations. 

 The Atlantic population has long been 

 extinct; the Korean population has been 

 severely reduced in numbers. The 

 present study concerns only the Cali- 

 fornia population. 



Most California gray whales spend 

 the summer (June through September) 

 in the northwestern Bering Sea and 

 the Chukchi Sea. A few summer along 

 the coast of northern California and 

 southern Oregon. 



The southward migrating whales 

 strike the Pacific coast of North 

 America between Vancouver Island 

 and San Francisco. They then travel 

 within about 4 miles of the shore 

 until they reach Baja California. A 

 few are believed to leave the coast 

 at Point Conception, moving past the 

 offshore side of the Channel Islands 

 before striking the coast again south 

 of San Diego. Most southbound whales 

 pass San Diego between the middle 

 of December and the middle of Feb- 

 ruary. 



In winter (early January to the end 

 of February) gray whales are scat- 

 tered along the Pacific coast from 

 about San Diego to Cabo San Lucas, 

 and in the southern end of the Gulf 

 of California. A few stragglers have 

 been observed in the northern Gulf 

 and at Guadalupe and Clarion Islands 

 as well as at various points as far 

 north as the coast of British Columbia. 



Calving takes place in shallow la- 

 goons, bays, and esteros. The five 

 important calving areas are: (1) Viz- 

 caino-Scammon; (2) San Ignacio and 

 (3) Magdalena, along the Pacific Coast 

 of Baja California; and (4) Yavaros 

 and (5) Reforma, on the east shore of 



the Gulf of California. San Diego Bay, 

 California, is no longer a calving 

 area. 



The northbound migrants pass San 

 Diego mainly in March and April. 

 They move along the coast, and many 

 pass the west side of Vancouver Island 

 before turning off into the North Pacific, 



The rate of migration is fairly uni- 

 form throughout the day. Movement 

 apparently is slightly greater in the 

 afternoon, when the fog tends to lift. 

 No data are available on rate of mi- 

 gration at night. For census purposes, 

 movement at night is held to be 50 

 percent of the daylight rate of 4 knots. 



Gray whales are not strongly gre- 

 garious during migration. They usu- 

 ally travel singly or in groups of two 

 or three. Singles, presumably pregnant 

 females, are common in the early 

 stages of the southward migration. 



Immature individuals and nonbreed- 

 ing adults predominate in the outer 

 channels near the entrances of breed- 

 ing lagoons; pairs and trios of courting 

 adults predpminate in the intermediate 

 areas, and cows with calves predomi- 

 nate in the inner "nursery" areas. 



Adult cows bear one calf at 2 -year 

 (or longer) intervals. Gestation ap- 

 parently lasts 11 to 12 months. 



Ehiring a 4 -season study in Laguna 

 Scammon, 12 dead calves and 2 dead 

 adults were found. The mean length 

 of 7 calves, measured in January and 

 February, was 13.25 feet. 



From 1850 to 1890, whaling opera- 

 tions along the coast of California and 

 Baja California reduced the California 

 gray-whale population of 25,000 to 

 50,000 to perhaps a few thousand. 

 From 1890 to 1924, the population 



