Effects of wild, semi-captive, and captive management on male Chiricahua leopard frog sperm quality with implications for conservation breeding programs

The Chiricahua leopard frog (Lithobates chiricahuensis) is a threatened species endemic to the southwestern United States and Northern Mexico. Captive breeding programs were established to support reintroduction efforts, yet reproductive output has been lower than needed for recovery of the species. This study aimed to evaluate the effects of captivity on amphibian reproduction by (1) determining if captive, semi-captive, and wild male L. chiricahuensis produce sperm at similar rates and concentration in response to hormone treatment; and (2) evaluating the quality of sperm obtained over time from these populations. Males from captive, semi-captive, and wild locations were administered a combination of human chorionic gonadotropin and gonadotropin-releasing hormone to stimulate sperm production and release. A high percentage of males in the captive (60%), semi-captive (100%), and wild (95.3%) populations produced sperm following treatment. Sperm quality (forward progressive motility and total sperm motility) did not differ between groups. However, sperm quantity (sperm/ml) differed (p < .05) between populations, with semi-captive and wild males producing higher concentrations of sperm than captive males. These results suggest that Chiricahua leopard frog sperm quantity, but not quality, may become negatively impacted by long-term captivity in indoor, controlled settings.