Hellbender Conservation Centre

To breed and reintroduce hellbenders to supplement stocks in the USA


Measuring about 60 cm in length, the hellbender is one of the largest species of salamanders in the world. There are two subspecies: the eastern hellbender (Cryptobranchus alleganiensis alleganiensis) and the Ozark hellbender (Cryptobranchus alleganiensis bishopi). In Missouri, both subspecies occur: The eastern hellbender still inhabits Meramec, Big, Gasconade, Big Piney and Niangua rivers and the Osage Fork of the Osage River. The Ozark subspecies lives in the Current, Jacks Fork and Eleven Point rivers, the North Fork of the White River and Bryant Creek.


Hellbender populations have declined throughout most of their range over the past hundred years due to various factors, yet seemed to do well in Missouri and Arkansas. The Ozark Mountains have been home to one of the largest and most stable populations until recently. However, since the 1970s, Eastern hellbender numbers have plummeted 80 percent. During the same period, Ozark hellbender numbers have declined by 70 percent. One of the biggest sources of concern about hellbenders is the failure of recent surveys to discover young specimens or other signs of reproduction. The species has practically disappeared from the streams it used to inhabit in Arkansas.


No single factor is known to have caused these precipitous declines. Dam building took a toll as reservoirs covered cold, fast-moving waters that hellbenders require. Gravel mining in streams and other human activity on nearby land allowed gravel and mud to smother more of their habitat. Declining water quality may have played a role, too. Hellbenders absorb oxygen - and anything else in the water - through their skin. Their extra sensitivity to pollution makes them a "canary in the coal mine" for water quality. Increasing recreational use of the streams where hellbenders live, e.g. by canoeing or angling, also has increased pressure on the species. Deliberate damage is a problem. Illegal collection for food and medicine in overseas markets and for the pet trade has decimated hellbender numbers in some rivers. In other areas, dozens of hellbenders have been found dead on stream banks, apparent victims of human ignorance.


An alarming number of hellbenders observed in recent years have misshapen toes, legs or eyes. Some are missing appendages. Others have tumors or other abnormalities. The severity of the problem varies from stream to stream. In the Current River, three-quarters of all hellbenders have some kind of deformity.


With a view of establishing an ex situ breeding programme and developing husbandry protocols for successfully rearing hellbender larvae to sexual maturity for possible reintroductions into the wild, and assisting and supporting in situ research investigating the possible causes for the rapid population decline, the Saint Louis Zoo has constructed a climate-controlled habitat capable of sustaining a potential breeding group of hellbenders in the Zoo’s Herpetarium.


Working with their partners, the Center for the Conservation of Hellbenders plans to concentrate not only on ex situ breeding but will also assist with in situ research projects dealing with stream quality assessment, hellbender health evaluations and population dynamics. If ex situ breeding is successful, the Center will work with the Missouri Department of Conservation to identify suitable historic sites for possible reintroductions.


WAZA Conservation Project 05001 is operated by the Saint Louis Zoo in cooperation with the Missouri Department of Conservation, the Arkansas Game and Fish Commission, the University of Missouri - Rolla, the Southwest Missouri State University, the University of Arkansas, and the United States Fish and Wildlife Service. The project is supported by AZA and a number of Accredited AZA-Institutions, AZA's Cryptobranchid Interest Group. 


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