Demographic Strategies Used in Managing Species Populations

6/21/20232 min read

shark against black background
shark against black background

In conserving and managing species populations, conservation organizations have employed techniques such as (i) facilitating instinctive and unprompted mating in captivity, (ii) introducing wild specimens for mating in zoos or reserves, as well (iii) adopting assisted reproductive technologies (“ART”).

Conservation-based programs in zoos tend to be expensive, space- and resource-intensive, impeded by regulatory obstacles, and often result in reduced genetic diversity of the founder species (Lueders and Allen 2020).

ART – which includes artificial insemination (“AI”) and embryo transfer (“ET”) – could aid genetic exchange and allow transport of ex situ genes back to natural habitats without disturbing species in their respective environments (Lueders and Allen 2020). In situ ART applications are limited by funding challenges, and the fact that female specimens in endangered populations tend to be less fertile (Lueders and Allen 2020) and few in number (Roth and Swanson 2018).

When AI has been applied, viable offspring and eggs have been generated in almost 60 exotic animals and more than 35 non-domestic bids (Roth and Swanson 2018).

AI can be achieved through cryopreservation and/or short-term sperm storage.

In the case of sharks and rays, cryopreservation has been observed to assist in preventing interbreeding, obviate the need for harmonized reproductive rhythms, and circumvent the requirement to convey sires between sites (Garcia-Salinas et al 2021). Cryopreservation in megafauna can also fortify remote populations and build a biobank of genetic material (Lueders and Allen 2020). However, cryoprotectants may be toxic and/or decrease sperm quality, and the process requires highly specialized tools and materials (Garcia-Salinas et al 2021).

In general, due to the heterogeneity of sexual morphology amongst taxa, ART is a highly specialized science even within each species, leading to a dearth of researchers and laboratories and consequently a scarcity in funding (Roth and Swanson 2018). Animal carers and managers may also be reluctant to accept ART for reasons of cost, potentially encouraging artificial behaviour, and apprehension about the welfare of their wards (Roth and Swanson 2018).

References:

  • García-Salinas, P., Gallego, V., and Asturiano, J.F. (2021). ‘Development of Sperm Cryopreservation Protocols for Sharks and Rays: New Tools for Elasmobranch Conservation’. Front. Mar. Sci. 8:689089. doi: 10.3389/fmars.2021.689089

  • Lueders, I. and Allen, W.R.T. (2020). ‘Managed wildlife breeding-an undervalued conservation tool?’ Theriogenology 150 (2020) 48e54 https://doi.org/10.1016/j.theriogenology.2020.01.058

  • Roth, T.L. and Swanson, W.F. (2018) ‘From petri dishes to politics – a multi-pronged approach is essential for saving endangered species’. Nature Communications | (2018) 9:2588 | DOI: 10.1038/s41467-018-04962-7