There is no doubt that hellbender populations have declined dramatically over the past several centuries, especially during the 1900’s.
Unfortunately, biologists don’t have much baseline data to go on – we don’t know how widespread hellbender populations were in the past because no one was studying hellbender populations in the 17- or 1800’s, or even into most of the 1900’s for that matter. It is clear, however, that hellbenders have declined in many stream over the past few decades and they are gone from large areas where good habitat probably once existed.
The good news is that there are still some very good hellbender streams remaining, mainly in Georgia, Tennessee, North Carolina, Virginia, and West Virginia. Several good streams also remain in some parts of Pennsylvania. Populations in the Ozark Mountains are nearly gone, or have drastically declined.
The only logical strategy now is to try to make sure that good streams remain good streams. This will take a lot of effort and careful planning in the way we as humans develop or protect landscapes.
So what’s causing the decline of hellbenders?
Siltation. This is by far the main cause of hellbender declines! The siltation of streams because of poor agricultural practices, urbanization (building housing developments along streams), poor forestry practices, and road-building are the major culprits leading to the degradation of many hellbender streams. Runoff of soil (sediment) into streams smothers rocks and basically chokes out the habitat that hellbenders and numerous other stream-dwellers need for survival.
Dams have greatly impacted hellbender populations. Many river systems, including the Tennessee and Ohio Rivers were once free-flowing, shallow rivers that could have supported large hellbender populations. Damming of these rivers and their tributaries have converted these habitats into slow moving lakes no longer suitable for species like the hellbender.
Killing of hellbenders by fishermen is still a problem in some heavily fished areas. Hellbenders are wrongly thought to be poisonous, or they are thought to eat large amounts of game fish. Both of these ideas are purely myths. In the early 1920’s and 30’s, there were actually bounties on hellbenders. These bounties, usually about 25 cents per hellbender, were aimed at eliminating hellbenders from “trout streams.” If you fish the streams in and around the mountains of the eastern United States, seeing a hellbender is one of the best indications that the stream you are in is extremely healthy!
Overcollection for the pet trade has dramatically reduced hellbender populations in some streams. Hellbenders live a long time and the young have low survival. This strategy makes hellbenders especially vulnerable to overcollection. If adults are taken out of their natural habitat, the population as a whole suffers.
Endocrine disruptors are just starting to be studied by several researchers as a possible reason for hellbender decline in the Midwest (Arkansas and Missouri). Some chemicals, including certain pesticides, are known to indirectly affect the reproduction of some animal species. Hellbender reproduction may be affected by some of the chemical compounds now found in their rivers. Go here to read about some of Dr. Yue-wern Huang’s research regarding endocrine disruption in amphibians.
The Conservation Status of Hellbenders
Hellbenders are not yet listed as an Endangered or Threatened Species by the federal government, but many states have given them protective status. “Protection”, however, doesn’t necessarily mean that hellbender habitat is protected from human impacts. In most cases protective status just means that hellbenders can’t be collected from the wild and that more information needs to be gathered about their status. Assessments are currently underway to determine whether they should be given federal protection. Federal status would greatly improve the ability of conservation biologists to actually protect the hellbender and its habitat.