Download Conserving the Eastern Hellbender in Tennessee

Conserving the Eastern Hellbender in
Tennessee
by Bill Reeves and Mary Pfaffko
Hellbenders are endemic to North America and are split into two subspecies, the eastern
hellbender, which is found throughout the eastern states, and the Ozark hellbender, which
is restricted to the Ozark Mountains of northern Arkansas and southern Missouri. These
remarkable salamanders have been around for over 65 million years, but both subspecies
have declined through the years due to loss of habitat, poor water quality, predation and
the introduction of invasive prey species.
Photo Credit: Brian Gratwicke
A partnership fueled by State Wildlife Grants has sparked innovations in on-the-ground
conservation to secure a future for a giant salamander found in clear, cold mountain streams in
Tennessee. In March 2013, the Tennessee Wildlife Resources Agency and the Tennessee
Hellbender Recovery Partnership were presented with a State Wildlife Action Plan Partnership
Award in recognition of their outstanding leadership in eastern hellbender conservation, and
efforts to prevent the subspecies from becoming endangered.
In fall 2010, when the U.S. Fish and Wildlife Service (Service) proposed listing both North
American subspecies of hellbender – the eastern (Cryptobranchus alleganiensis alleganiensis)
and the Ozark (Cryptobranchus alleganiensis bishop) – as federally endangered, after both
experienced precipitous declines throughout their ranges since the early 1990s. These two
subspecies are North America's contribution to the world's giant salamanders. Only two others
exist, the Japanese (Andrias japonicas) and Chinese (Andrias davidianus) giant salamanders, and
all are in trouble—threatened by man's activities.
With the eastern hellbender's federal status under review, the Tennessee Wildlife Resources
Agency (TWRA) looked to assess the status of hellbenders in Tennessee. At the time, its status
was believed to be as precarious as its cousin in the Ozarks, but the data were not available to
support this assumption. Local hellbender experts were enlisted to help develop projects to
determine whether Endangered Species Act (ESA) protection was needed. The experts included
Dr. Brian Miller, a professor at Middle Tennessee State University, Dale McGinnity, curator of
ectotherms at the Nashville Zoo, and Dr. Michael Freake, a professor at Lee University in
Cleveland. Their extensive knowledge, experience, and passion for hellbender conservation
informed a number of TWRA projects that would produce the data needed to adequately
contribute to the federal status determination.
First, surveying efforts helped paint a more complete picture of the hellbenders' status in
Tennessee. Hellbender distribution and abundance within its historic range had declined severely
over the last 20 years. Middle Tennessee hellbenders were present in only four Tennessee River
tributaries, and they were not collected from the Cumberland or Barrens Rivers systems—places
where they were once abundant. Hellbenders were also missing from a number of streams that
once boasted viable populations in years past. Several relict populations of old individuals
exhibited a lack of recruitment with either no reproduction or recruitment of young. A genetic
survey of tissue samples taken from individuals from each river system distinguished two
genetically distinct populations—the Duck and Hiwassee river system populations. This
knowledge will help guide future restocking efforts that help maintain maximum genetic
diversity.
Biologists search for hellbenders in Tennessee's Big Swan Creek. These giant salamanders
spend the day in natural or self-excavated dens beneath large rock slabs or logs at the
bottom or streams and rivers, emerging only at night to forage for food.
Photo courtesy of the Association of Fish & Wildlife Agencies
Second, to enhance the sampling process, Dr. Freake, with the help of Dr. Stephen Spear, an
assistant conservation scientist with the Orianne Society, developed a new protocol to detect the
presence of eastern hellbenders—an innovation that will continue to affect conservation across
the range of the species. All organisms shed genetic material into their environment through
feces, mucus and urine. This DNA is known as environmental DNA (eDNA). Just as forensic
scientists use DNA to prove presence at a crime scene, eDNA can be used to detect aquatic
organisms. This new process exponentially decreased the labor and money it takes to locate the
presence of hellbenders by snorkeling through streams. It also increased the effectiveness of
regular surveying techniques for hellbenders. In 2011, hellbender presence was detected at sites
where regular survey efforts had failed to detect the species. The highest levels of DNA were
found at sites of known reproducing populations, suggesting the promise for correlating DNA
levels with abundance. These data have been incorporated into the Tennessee Wildlife Action
Plan to strategically update the actions needed to continue restoring the species over the years to
come.
Third, new techniques and protocols for restoring the hellbender were developed. A new
cryopreservation technique developed by McGinnity was used to produce the hellbender—
drawing from the first gene bank for any amphibian species, and with perfected hormonal
induction and artificial fertilization techniques, McGinnity produced the first-ever captive-bred
eastern hellbenders. Furthermore, he and Dr. Debra Miller at the University of Tennessee,
Knoxville developed new sampling protocols for better understanding the impact of ranaviruses
(family Iridoviridae) and chytrid fungus (Batrachochytrium dendrobatidis) on hellbender
populations. These disease organisms have caused declines in amphibian populations worldwide.
Dr. Miller performed the pathogen determinations, and both were detected.
The primary funding source for the hellbender project was the State and Tribal Wildlife Grants
Program, which is funded annually by the U.S. Congress and administered to state fish and
wildlife agencies through the Service. The program helps works to prevent the need to list
wildlife as endangered or threatened under the Endangered Species Act by conserving at-risk
species and keeping common species common through the implementation of State Wildlife
Action Plans. The hellbender project is an exciting example of the program's success.
Bill Reeves, Chief of the Tennessee Wildlife Resources Agency's Division of Biodiversity, can
be reached at [email protected]. Mary Pfaffko, Teaming with Wildlife Associate at the
Association of Fish & Wildlife Agencies, can be reached at [email protected].