Pup 



Table l.— Observation data on sea otter No. 34 and her six pups. 



Date 

 pup first seen 



Approximate age of 

 pup when first seen 



Date 

 pup last seen 



First date female 

 seen without pup 



Approximate 

 dependency period 



Apparent 

 gestation period 



Table 2. — Observation data on sea otter No. 41 and her four pups. 



Pup 



Date 

 pup first seen 



Approximate age of 

 pup when first seen 



Date 

 pup last seen 



First date female 

 seen without pup 



Approximate 

 dependency period 



Apparent 

 gestation period 



pup (Table 2). She was seen with a second pup 

 judged to be about 1.5 mo old on 28 February 1978. 

 This mother-pup pair was seen on numerous occa- 

 sions through 7 September 1978. Apparently the 

 mother and pup separated after about 8 mo. 

 Number 41 was observed with a third pup, also 

 judged to be approximately 1.5 mo old, on 13 March 

 1979. This pair was observed often through 5 May 

 1979. Neither was seen again until 10 July 1979 

 when No. 41 was seen, red nosed, with a male but 

 without her pup. The third pup, therefore, proba- 

 bly was 3.5-5.5 mo old when separated from its 

 mother. Number 41 was seen with a fourth pup, 

 judged to be 1.5 mo old, on 31 December 1980, and 

 was still with the female at the time of writing. 

 Since it is not possible to determine with cer- 

 tainty when conception or blastocyst implantation 

 occurred, we can only speculate on the gestation 

 period for the pups of No. 34 and 41. On 10 August 

 1977, No. 34 was seen with a second pup and on 12 

 and 13 August 1977 she was seen without her 

 second pup and with a male escort. Photographs of 

 her head region taken on 13 August 1977 showed 

 nose damage indicating recent copulation. She 

 was subsequently recaptured on 2 March 1978 

 with a third pup that weighed 3.6 kg. Assuming 

 the pup was 1.5 mo old at capture and that concep- 

 tion occurred in mid- August 1977, the gestation 

 period was about 5 mo. Number 34 and a fourth 

 pup were last seen together on 13 September 1979. 

 She was seen without a pup and with a male com- 

 panion on 22 September 1979 and by 24 September 

 1979 her nose again exhibited evidence of recent 

 copulation. We monitored No. 34 closely for the 



next several months. She was last seen without a 

 pup on 14 March 1980; then with a fifth pup on 27 

 March 1980. If conception took place on 22-24 Sep- 

 tember 1979, gestation was close to 6 mo. 



Number 41 was separated from a pup in early 

 September 1977, coincident with the appearance 

 of a male companion. She had a swollen nose on 8 

 September 1977 and on 28 February 1978 was seen 

 with an estimated 1.5-mo-old pup. Assuming con- 

 ception occurred in early September, the gestation 

 period was a little over 4 mo. Her second pup was 

 "weaned" in early September 1978. A third pup, 

 judged to be about 1.5 mo old when first observed 

 on 13 March 1979, was also born just over 4 mo 

 after separation of the second. 



Our observations indicate that at the time of 

 separation (weaning) three of the eight separated 

 pups were large enough at 8-8.5 mo of age to have a 

 good chance of survival. Two pups between about 

 3.5 and 6 mo, although rather small, may have 

 survived. Some independent animals have been 

 documented in the 9-12 kg range (Loughlin 1977; 

 Wild and Ames ). The remaining three almost cer- 

 tainly died. 



Estimates of the gestation period for captive sea 

 otters, presumably based upon more definitive 

 data, range from 5.5 to 8 mo (Brosseau et al. 1975; 

 Antrim and Cornell 1980; Antrim^). Our esti- 



■"Wild.P. W.,and J. A. Ames. 1974. A report on the sea otter, 

 Enhydra Ititris L., in California. Calif Dep. Fish Game, Mar. 

 Resour Tech. Rep. 20, 93 p. 



'J. Antrim, Curator of marine mammals. Sea World, Inc., 1720 

 South Shores Road, San Diego, CA 92109, pers. commun. June 

 1980. 



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