Over the past half-century, the Eastern Hellbender has experienced precipitous population declines throughout its range. Once common in the rocky rivers and streams in which it was found, most remaining healthy populations have been restricted to high quality, forested watersheds isolated from human disturbance. Indiana populations were especially affected, with the species approaching near extirpation and remaining only in the Blue River in southern Indiana.
To reverse these declines and recover the species, we have implemented a long-term reintroduction program. In the Blue River, we identified high-quality sites and started releases in 2017, and we’ve continuously been evaluating other rivers and streams in southern Indiana for their potential for future population restoration efforts. Thus far, we have released over 500 juvenile Hellbenders into the Blue River and identified two additional streams with suitable habitat for future releases.
It is important that these released animals have the maximum chance of survival after release. To accomplish this, we combine summer releases with captive-conditioning and soft-release efforts. All of our animals are raised in captive conditions designed to mimic the Blue River to ensure each individual is prepared for life in the wild. These conditioned animals are then released in early-mid-summer into soft-release cages to allow for a short acclimation period and then fully released after 72 hours. This combination of release techniques has resulted in a 74% first year survival, nearly matching that of previously monitored adults. It is our hope that continuous use of these efforts, combined with habitat management and improved captive-rearing techniques, will successfully result in the recovery of the species in Indiana and help inform recovery efforts nationwide.