Hellbenders have been in the fossil record for over 160 million years, but at the turn of the 21st century, North America’s largest aquatic salamander was in danger of local extinction in Missouri.
“We’ve studied this animal a long time, and we’ve noted up to 80% decline throughout our state,” said Jeff Briggler, state herpetologist for the Missouri Department of Conservation. “But due to all our propagation efforts at the St. Louis Zoo, and the ground that we have gained recently, I am actually a lot more hopeful and know that in my lifetime, we have at least saved hellbenders for another generation while we continue to study them."
Since 2001, Briggler and others have worked with representatives from the Missouri Department of Conservation, U.S. Fish & Wildlife Service and the St. Louis Zoo to help bolster hellbender populations by breeding them in captivity for eventual release. More than 8,600 zoo-raised hellbenders have been reintroduced to Missouri waterways since the collaboration began.
Even so, the aquatic salamander still faces challenges. Today, only 1,980 hellbenders are estimated to live in the wild in Missouri. In addition to being impacted by poor water quality, other threats include degrading habitat, water quality diseases (such as amphibian chytrid fungus), predation and illegal collecting.
“As the forest is cleared down and it rains real heavy, all this sediment and [fine sediment] go into our river systems. And they actually choke out the habitat that hellbenders live in,” Briggler said.
Briggler is no stranger to the hellbenders’ habitat. In fact, he’s one of very few people who is an expert at finding hellbender nests in the wild. He snorkels, and sometimes scuba dives, in order to collect eggs for the zoo. He looks for clusters of pea-size eggs, as well as the adult male hellbenders tasked with guarding the nests.
“If he tries to attack me or bite me when I'm approaching him under the river, then there's a high probability that he does have eggs behind him,” Briggler said. “So then we just use a clever little hook to remove them out from behind.”
Once the eggs are delivered to the zoo, the challenge of creating a space for successful hatchings begins.
“They're an underwater animal, so that does provide a whole unique challenge to their care. … It's not like working with a terrestrial species at all,” said Mark Wanner, the St. Louis Zoo’s herpetology manager. “We try and match water quality to the native rivers, we also match temperature, light cycles, all of those things. We are trying to give them the best opportunity to be a wild animal as they're released.”
At the St. Louis Zoo’s herpetarium, Wanner is now working with close to 800 recently hatched hellbender larvae from wild eggs pulled from two Missouri rivers.
For both Wanner and Briggler, success would mean their program is no longer required to keep hellbender populations stable. But for now, they are focused on the small victories as they release hundreds of hellbenders into the wild each year.
“We know their survivorship has been very well to this point; the animals that we're catching to date appear very healthy. We do know they're producing viable sperm [and] the females are putting on eggs. So all the indications are showing we're making progress,” Briggler said.
“The biggest milestone we're waiting for next is to find a mother or dad that was raised at the St. Louis Zoo [and] released into the wild actually reproducing, laying eggs and having fertilized eggs. Every year, we're getting closer to that … and I just feel like we're making really good progress for this animal.”
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