Abstract

Captive sea otters are owned by the United States Fish and Wildlife Service (USFWS). The USFWS has requested that sea otters be prevented from breeding in order to save captive space for wild rescued animals that might be deemed non-releasable. Suprelorin® or deslorelin, is a contraceptive that has been used in many different species to effectively suppress reproduction but duration of effect may vary between species and individuals.^1,2 The effects of one to several consecutive deslorelin implants on gonadal reproductive hormones found in fecal samples from six captive sea otters (2=male, 4=female) was compared to baseline pre-deslorelin levels for each individual and two control otters (1=male, 1=female) housed at three zoological institutions. The longitudinal hormone signatures of different stages of the contraceptive cycle were documented including pretreatment, initial stimulatory phase, effective contraception and hormone reversal characterized by a return to normal cycling reproductive levels. All sea otters exhibited effective contraception of gonads as evidenced by significantly lower concentrations of fecal reproductive hormones compared to pretreatment or control animal levels. However, the initial stimulatory phases and duration of contraception were highly variable at 0 to 9 months, and 6 months to 4 years, respectively.

Acknowledgments

The authors thank the Oregon Zoo and the Georgia Aquarium for their collaboration and assistance.

Literature Cited

1.  Bertschinger, H.J., T.E. Trigg, W. Jöchle, and A. Human. 2002. Induction of contraception in some African wild carnivores by down regulation of LH and FSH secretion using the GnRH analogue deslorelin. Repro Suppl 60:41–52.

2.  Munson, L., J.E. Bauman, C.S. Asa, W. Jöchle, and T.E. Trigg. 2001. Efficacy of the GnRH analogue deslorelin for suppression of oestrous cycles in cats. Repro Fertil Suppl 57:269–73.