242 



NORTH AMERICAN FAUNA 74 



According to Clark (1887), the calves were set free with the expectation that they 

 would be fostered by other females. I suspect that many of those calves did not 

 survive. 



The increased mortality brought about by these practices apparently resulted 

 in a drastic decline of the Pacific walrus population in the late 19th century 

 (Allen 1880, 1895; Clark 1887), and this ebb was perpetuated in some degree by 

 continued commercial harvests in the beginning of the 20th century (Dobbs 

 1911; Chandler 1943; Madsen and Douglas 1957). That the population was at a 

 very low level in the early 1900's was recognized in both North America and 

 Eurasia (Dobbs 1911; Arsen'ev 1927; Chandler 1943; Fay 1957; Krylov 1968). 

 According to Madsen and Douglas (1957), the United States government in 1909 

 prohibited commercial harvesting of walruses within Alaskan territorial waters. 

 This prohibition did not apply to the taking of walruses on the high seas or in 

 Soviet waters, however, which continued at least until 1913. At that time, the 

 prices for ivory and hides steeply declined on the American market, making it no 

 longer profitable to hunt walruses commercially (Madsen and Douglas 1957). 



Some commercial hunting by Americans resumed after World War I (Nechi- 

 porenko 1927; Arsen'ev 1927; Chandler 1943). This hunting apparently was 

 much less intensive than before, partly due to scarcity of walruses, discourage- 

 ment by Soviet patrols, and further regulation. The killing of walruses in Alaska, 

 except for local use by natives, was prohibited by U.S. Department of Commerce 

 regulation in 1937 and by the Congressional "Walrus Act" of 1941 (Ch. 368, 55 

 Stat. 632, 48 U.S.C. 248). Ten years earlier, however, the Soviet government had 

 begun an intensive commercial harvesting program from vessels (Zenkovich 

 1938a). Those harvests from 1931 to 1957 apparently precipitated the second 

 major decline of the Pacific walrus population (Geller 1957; Kleinenberg 1957; 

 Fay 1957; Kosygin 1975a). It is from that low ebb that the population is recov- 

 ering at present. 



Rigid regulation of harvests by both the Alaska Department of Fish and Game 

 and the Soviet Ministry of Fisheries, beginning in the late 1950's, limited the 

 numbers taken and were especially restrictive of the taking of females and 

 young. The harvests before that time probably had included more females than 

 males (Burns 1965); this was changed by the new regulations to about 75% bulls, 

 20% cows, and 5% immature animals. That change probably had a consider- 

 able effect on the composition of the population itself, tending to enhance its 

 productivity by increasing the proportion of females in the population. 



At the same time, both the Soviet Union and the State of Alaska provided 

 protection to herds using the major hauling grounds on shore. Walrus hunting 

 was forbidden on and near eight hauling grounds in the Soviet Far East (V. 

 Mineev, personal communication) and on one (Round Island) in Alaska. Thus, 

 the impact of human predation on the Pacific walrus population was consid- 

 erably lessened during the 1960's and 1970's. 



Enumeration 



Marine mammal populations in general are difficult to census direcdy because 

 they tend to be "patchy" in distribution, unequally visible (some being under 

 water), and distributed over enormous areas that are difficult or impossible to 



