CONTENTS XIII 



Page 



36. Estimated world population of sea otters 190 



37. Changes in sea otter population density in six areas 193 



38. Present and projected sea otter populations in 



certain Alaska areas 194 



39. Sea otters tagged at Amchitka Island, Alaska 202 



40. Recoveries of tagged sea otters at Amchitka Island 203 



41. Prenatal sex ratio at Amchitka Island 206 



42. Sex ratio of sea otters killed at Amchitka Island 



during experimental harvests 207 



43. Sex and age of sea otters taken in seven areas 



frequented mostly by females at Amchitka Island 209 



44. Sex and age of sea otters taken in three areas 



frequented mostly by males at Amchitka Island 210 



45. Activities of a mated pair of sea otters during 



observations on 19, 20, and 21 August 1955 214 



46. Adult female sea otter reproductive tracts from 



Amchitka Island 225 



47. Phases of reproduction in the female sea otter as 



shown by status of ovaries and size of conceptus 226 



48. Frequency of primiparous and multiparous sea otters 226 



49. Uterine horn of pregnancy 226 



50. Weight distribution of embryonic and fetal sea otters 227 



51. Reproductive status of adult nonpregnant sea otters 228 



52. Sea otters counted along 5.5 km. of shoreline, 



Kirilof area, at Amchitka Island, Alaska 235 



53. Percent of fetuses in each weight class 243 



54. Frequency of unimplanted and implanted 



pregnancy, by season 244 



55. Mortality of sea otters, by age and sex, at 



Amchitka Island, Alaska, 1956-63 255 



56. Age and sex of otters found freshly dead on 



Amchitka beaches 260 



57. Abnormal conditions found in sea otters that died 



on beaches of Amchitka Island, Alaska 262 



58. Summary of observations from 83 sea otters found 



dead at Amchitka Island, Alaska, 1959 262 



59. Sea otter mortality in relation to population counts 



and available habitat, eastern half of Amchitka 266 



60. Foods offered to captive sea otters 294 



61. Food consumption of a 39-lb. (17.7 kg.) sea otter 



(Susie) at the Seattle Zoo 295 



62. Activity of a captive sea otter in daylight hours, 



summer (1957) and winter (1960) 304 



63. Conditions during sea otter observations at the 



Seattle Zoo 305 



64. Comparison of daily activities of wild and captive 



female sea otters in summer 307 



