The release occurred over the summer and consisted of 45 animals reared at the Columbus Zoo. Another 144 salamanders came from eggs reared at the Toledo Zoo. The release is part of an effort to re-establish the eastern hellbender, the largest amphibian in Ohio and one of the largest in the world. The plan aims to establish multiple, self-sustaining hellbender populations in at least six Ohio watersheds. State officials say the hellbender plays a key role in the state's natural heritage, and its' presence is an indicator of healthy habitats.