CAPTIVE BREEDING

Captive breeding can contribute, when combined with cryopreservation, to the conservation of a species through maintaining a source population, and the production of animals for release (Aquaculture). However, a major limitation of captive breeding is the difficulty of maintaining genetic diversity (Inbreeding Depression). Selection in the captive environment is shown by the rapid development of genetic traits such as size or colour particularly in fecund aquatic animals such as fish and amphibians. For example in fish changes in breeding patterns and domestication occur within a few generations.

To maintain the maximum diversity in a captive population all individuals should contribute equally to the following generation. This can only be achieved by keeping animals in randomly picked isolated pairs. A equal number of progeny must then be kept from all pairs. The minimum number of animals for an acceptable captive breeding program where it is expected there may be more than a few generations should be about 50 males and females. Even this number cant guarantee the maintenance of a viable population.

Consequently, even in the short term captive populations should be considered as surrogates for cryopreserved genetic material (Reproduction Technology). Even if a few females with a low genetic diversity can be maintained in captivity cryopreserved sperm can be used to preserve the whole nuclear genome of the species. When animals are raised for release their chance of survival should be that of the original population and guaranteed by the use of cryopreserved sperm to confer genetic competence.