Degree
Bachelor of Science in Wildlife, Fisheries, and Aquaculture
Major(s)
Wildlife, Fisheries, and Aquaculture
Document Type
Immediate Open Access
Abstract
The hellbender (Cryptobranchus alleganiensis) is the United States’ largest aquatic salamander and is mainly found across the eastern U.S. There are two subspecies of hellbenders, one of which is listed as endangered by the US Fish and Wildlife Service and the other considered a species of conservation concern and a candidate for listing under the Endangered Species Act. There have been several captive breeding programs established at zoos and universities across the U.S., which require a dependable method for sexing their individuals. Ultrasound imaging has previously been used to identify the sex of other amphibian species and track reproductive development. This study investigates the use of ultrasonography to identify the biological sex of captive hellbenders. Seven hellbenders were randomly chosen from a captive population and examined via ultrasound over three different trials using no sedation or anesthesia. During each trial, individuals were graded on a scale of 1-5. A value of 1 represented dense tissue, meaning the animal could be male or a juvenile female. A value of 3 represented developing follicles and 5 represented mature follicles, with both values resulting in a female prediction. Only one individual was given the same grade for all trials with 100% confidence level. All other individuals had at least one trial where reproductive structures were unable to be visualized and were labeled “no data.” Gravid females were the easiest to sex, likely due to their large reproductive structures. It was difficult to distinguish between males and juvenile females with the ultrasound imaging alone. Overall, the study was limited by several factors, both biologically and methodically. These include the age of the animals, the timing of the study, the small dataset, and the sub-optimal position of the ultrasound probe. In the end, ultrasonography may need to occur closer to breeding season or possibly a different restraint method to obtain more reliable sex predictions.
Date Defended
4-28-2025
Funding Source
Institute of Museum and Library Services
Thesis Director
Dr. Andy Kouba
Second Committee Member
Dr. Carrie Vance
Third Committee Member
Dr. Anthony Neal
Recommended Citation
Collom, Logan N., "Ultrasonography as a Method for Identifying Biological Sex in Captive Hellbenders (Cryptobranchus alleganiensis)" (2025). Honors Theses. 186.
https://scholarsjunction.msstate.edu/honorstheses/186
