MODERN POPULATIONS, MIGRATIONS, DEMOGRAPHY, TROPHICS, AND HISTORICAL STATUS OF THE PACIFIC WALRUS by Francis H. Fay with Brendan P. Kelly, Pauline H. Gehnrich, John L. Sease, and A. Anne Hoover Institute of Marine Science University of Alaska Final Report Outer Continental Shelf Environmental Assessment Program Research Unit 611 September 1984 231 TABLE OF CONTENTS Section Page ABSTRACT. .237 LIST OF TABLES. c .239 LIST OF FIGURES . .243 ACKNOWLEDGMENTS . ● . ● . ● . ● . 245 I. INTRODUCTION. ● ● . .246 A. General Nature and Scope of Study . 246 1. Population Dynamics . 246 2. Distribution and Movements . 246 3. Feeding. .247 4. Response to Disturbance . 247 B. Relevance to Problems of Petroleum Development . 248 c. Objectives. .248 II. STUDY AREA. .250 111. SOURCES, METHODS, AND RATIONALE OF DATA COLLECTION . 250 A. History of the Population . 250 B. Distribution and Composition . 251 c. Feeding Habits. .255 D. Effects of Disturbance . 256 IV. RESULTS . .256 A. Historical Review . 256 1. The Russian Expansion Period, 1648-1867 . 258 2. The Yankee Whaler Period, 1848-1914 . 261 233 TABLE OF CONTENTS (Continued) Section w 3. From Depletion to Partial Recovery, 1900-1935 . 265 4. The Soviet Exploitation Period, 1931-1962 . 268 5. The Protective Period, 1952-1982 . 275 B. Distribution and Composition . 304 1. Monthly Distribution . 304 2. Time of Mating . .311 3. Location of the Breeding Areas . 312 4. Time and Place of Birth . 316 5. Sex/Age Composition . 318 c. Feeding Habits. .325 1. Winter, Southeastern Bering Sea . 325 2. Winter, Southwestern Bering Sea . 330 3. Spring, Eastern Bering Sea . 330 4. Summer , Chukchi Sea . .337 5. Amount Eaten in Relation to Age, Sex, Season . 341 D. Responses to Man-made Disturbance . 348 1. On Ice, in Winter . 349 2. On Ice, in Spring and Summer . 349 3. On Shore, in Spring, Summer, and Fall . 351 4. In Water, All Seasons . .352 5. The Consequences of Disturbance . 352 234 TABLE OF CONTENTS (Continued) Section ,Page v. DISCUSSION AND CONCLUSIONS . 354 A. Demographic History . 354 B. Distribution and Movements . 358 c. Feeding . .359 D. Response to Disturbance . 360 VI. LITERATURE CITED . .361 VII. APPENDIXA. .376 235 ABSTRACT The Pacific walrus population probably was not greatly affected by the incursions of the Russian merchant companies in the 18th and early 19th centuries, because their catches were mostly small and mainly of adult males. But it was severely depleted at least three times after the pur- chase of Alaska from Russia, first by the Yankee whalers between 1868 and 1880, when they tookat least 130,000 animals , mainly adult females. The second depletion was by the American “arctic traders” in the beginning of the 20th century, when they extirpated most of the herds summering in the Bering Sea and greatly reduced those in the Chukchi, as well. The third depletion was by Soviet sealers in the 1930’s to 50’s, when they took at least 140,000 animals and again brought the population to a low level. The depletionby the Yankee whalers was perhaps the most devastating of the three, because it struck quickly and intensively at a stationary popula- tion, made up mainly of old, unproductive animals. It had recovered only partially by the time the traders began their taking, but by then it was broadly based in young, productive animals, hence more adaptive and resil- ient than before. Following the traders, it probably nearly recovered to its 18th century size before the Soviets began their intensive catching. Although they removed nearly as large a number of animals as the whalers had, the youthful, resilient population was better able to withstand and compensate for the increased mortality. Recovery from that third depletion took about 25 years, and the population apparently reached its new maximum in the late 19701s. It now contains a large proportion of old animals, whose productivity is low and has been lowered still further by a high rate of fetal abortion, possibly attributable to malnutrition, an infectious agent, or a combination of those factors. Its recruitment has been very poor in recent years, due to high postnatal mortality of calves. With such low recruitment and with steeply rising catches in both Alaska and Chukot- ka, the population probably is in a decline again at present. Pacific walruses currently inhabit nearly all of their pre-19th centu- ry range. Apparently, nearly all of the adult males now summer in the Bering Sea, while all of the females and young summer in the Chukchi. In autumn, the males and females evidently meet in the Bering Strait region, before moving into their wintering-breeding areas in the Bering Sea. In the breeding areas, the adult males evidently eat little or no food during the rut. The adult females apparently eat little during the summer, possi- ble associated with their annual molt. Animals in the western Chukchi Sea in summer appear to be as dependent on polychaetes and ringed seals as they are on mollusks. Walruses are more easily disturbed by odors than by sight or sound of man and his machinery. Herds of females and young in the eastern Chukchi Sea in summer are likely to be affected by man-made disturbance, mainly through separation of calves from their mothers. 237 LIST OF TABLES Table 1. Average dimensions of tusks and snout of Pacific walruses in each age class. Table 2. Amounts of walrus ivory acquired by the Russian hunting companies in the Bering Sea, 1743-1860, as reported in Soviet literature. Table 3. Use by walruses of haulout areas on the coast of Chukotka per decade, 1920-1980. Table 4. Use by walruses of haulout areas on Alaskan shores of the northern Bering Sea and Chukchi Sea in the present century. Table 5, Estimated size of the Pacific walrus population, based on Soviet-American cooperative censuses in 1975 and 1980. Table 6. Chi-square goodness of fit test, comparing observed with expected frequencies of occurrence of parturient animals in samples of adult females from the spring catches of walruses at Diomede and Gambell 1952-1982. Table 7. Goodness of fit comparison of observed with expected frequencies of occurrence of parturient animals in catches at Diomede and Gambell, based on mean age of the catch. Table 8. Frequency of occurrence of parturient, pregnant, and barren females in non-selected samples of adult walruses taken during Soviet and joint Soviet- American research cruises, 1972-1983. Table 9. Frequency of occurrence of new pregnancies in the catch samples from Diomede and Gambell, in relation to expected values, 1952-1982. Table 10. Relative abundance of the younger cohorts of walruses in visually classified samples from the Bering and Chukchi seas, 1981-1983. Table 11. Comparative frequency of occurrence and numbers of anasakid nematodes parasitizing the stomach of Pacific walruses in spring, harvest samples, 1964- 1982. Table 12. Comparative sternal blubber thickness of Pacific walruses, 1958-1983. Table 13. Comparative composition of walrus groups in five sectors of the pack ice of eastern Chukchi Sea in late July 1981. 239 Table 14. Percentage frequency of occurrence of group sizes of walruses on ice versus in the water, eastern Chukchi Sea, 16-28 July 1981. Table 15. Percentages of walruses in each sex/age class per compositional sample, eastern Chukchi Sea, July 1981. Table 16. Percentage representation of sex/age classes of walruses in completely classified groups on ice, in relation to group size, eastern Chukchi Sea, 16-28 July 1981. Table 17, Percentage composition “of walrus herds in the eastern and western Chukchi Sea, July-August 1982. Table 18. Daily compilation of sightings of walruses within 1 km of the ship’s track, in relation to activity. Table 19. Contents of the stomachs of 15 walruses taken in outer Kuskokwim Bay, during February-March 1981. Table 20. Comparative thickness of sternal blubber in adult male and adult female walruses taken in southeastern Bering Sea, February-March 1981. Table 21. Contents of the stomachs of four male walruses taken in Bristol Bay, April 1981. Table 22. Contents of the stomachs of five male walruses taken in the vicinity of Mekoryuk and Etolin Strait, Nunivak Island, in May and June 1982. Table 23. Contents of stomachs of 108 walruses taken in the vicinity of St. Lawrence Island, April-June 1980 and 1982. Table 24. Stomach contents of eight walruses taken from the vicinity of Nome to King Island, May 1980 and 1982. Table 25. Stomach contents of 50 walruses taken in Bering Strait, May-June 1980 and 1982. Table 26. Stomach contents of 20 walruses taken in west- central Chukchi Sea, July-August 1983. Table 27. Stomach contents of 20 walruses taken along the northern coast of Chukotka, from Vankarem to long Strait, July-August 1983. Table 28. Mean daily energy intakes by pregnant and lactating female walruses at Marineland. Table 29. Flight distances of walrus herds when disturbed by the ship, its helicopters, and two types of small boats, during the cruise of the CGC POLAR STAR, Chukchi Sea, July 1981. 240 Table 30. Flight distances of walruses when they were approached upwind, crosswind, and downwind by the K/S ENTUZIAST, in the ice edge of the Chukchi Sea, July-August 1982. Table 31. Comparative social, reproductive, and demographic characteristics of Pacific walrus and African elephant populations. 241 LIST OF FIGURES Figure 1. The range of the Pacific walrus population, relative to actual and proposed oil lease areas on the western Alaskan outer continental shelf. Figure 2. Facial outlines used for classification of walruses by age, during visual surveys of group composition. Figure 3. Estimated annual catch of Pacific walruses by the Yankee whalers in the Bering-Chukchi region, 1849- 1910. Figure 4. Distribution of sightings and catches of walruses by the Yankee whalers in June-August, during the first 20 years of their harvesting.