Post-release comparisons of amphibian growth reveal challenges with sperm cryopreservation as a conservation tool

Abstract

Conservation translocation using captive-bred individuals has become increasingly important for species restoration. Despite advancements in technologies for captive-breeding, such as gamete cryopreservation, it remains largely unknown if these artificially-produced offspring can be used to establish a viable wild population. Using an amphibian species with a stable conservation status (Anaxyrus fowleri), we measured the post-release growth and survivorship of offspring produced from frozen/thawed sperm and projected fecundity and population differences. Cryo-derived tadpoles and post-metamorphic toadlets were smaller than their natural counterparts. Model projections show that early-life differences in growth can scale up to substantial differences in final life fecundity and population trends. Our findings call for greater attention towards the differences between captive-bred and cryo-derived individuals compared to their natural counterparts, and the need for more investment into developing cryopreservation technologies that are viable at the population level for conservation translocation.