Eastern Hellbender Status Assessment Report

Abstract

The eastern hellbender (Cryptobranchus alleganiensis alleganiensis) is a folly aquatic, giant salamander characterized by a large, flat head; wide neck; dorso-ventrally flattened, heavily wrinkled body; and keeled tail. Hellbenders average 50 centimeters (cm) in length with some individuals reaching up to 74 cm. Coloration is variable, but can be generally described as dark green or gray dorsally and lighter on the underside. Irregular, dark spots, brownish or black in color, are often present on the dorsal surface. Hellbenders have been known to survive as long as 29 years in captivity. Extrapolations from growth rate data suggest that some very large individuals may live as long as 30 years in nature. Hellbenders are found in habitats with swift running, fairly shallow, highly oxygenated waters. The presence of riffle areas with flat rocks, logs and other cover is essential for feeding and breeding activities. The primary food source for hellbenders are crayfish, although fish and other organisms will occasionally be consumed. Hellbenders are often found concealed beneath rocks with only their head protrading and will seize prey that swim within a few inches with a quick sideways movement, snapping as the food item passes. In general, eastern hellbender populations have a short breeding season that begins in mid- to late August and lasts through mid-September. Nests are normally excavated beneath large, flat rocks, crevices or holes in bedrock, or similar structures. Historically, eastern hellbenders were found in the Susquehanna system (Atlantic drainage) in New York, Pennsylvania, and Maryland; tributaries of the Savannah River (Atlantic drainage) in South Carolina and Georgia; the Tennessee system in Georgia, Virginia, Alabama, Mississippi, Tennessee, North Carolina, and Kentucky; the Ohio system in New York, Maryland, Pennsylvania, Virginia, West Virginia, Ohio, Indiana, Kentucky, and Illinois. A secondary cluster of populations inhabits portions of the Missouri drainage in south-central Missouri and the Meramec (Mississippi drainage) in eastern Missouri. Because of their secretive nature and the confusion with mudpuppies (Necturus maculosus) the current range of the eastern hellbender is not known with certainty. They are almost certainly extirpated from the Ohio drainage in Illinois and have been eliminated from Indiana, except for a small population in the Blue River and the lower portions of the south fork of the Blue River. In Ohio, hellbenders are no longer found in the Miami River or its tributaries. Although populations persist in other portions of the Ohio system and in the Susquehanna, Allegheny, and Tennessee systems, the species appears to be absent from many historical sites. No recent data are available for the Savannah drainage populations in Georgia and South Carolina. The Missouri populations have declined by an average of 77 percent in the past 20 years. Habitat alterations, including siltation, water impoundment, and water quality degradation are likely the greatest threats to eastern hellbenders. Other threats include incidental take by anglers, collection for the pet trade, and predation by non-native fish. Furthermore, hellbenders may suffer from low genetic variability, recruitment may be limited by endocrine disruption, and adverse effects could result from a complex of interactions associated with global climate change. Although the level of protection provided to eastern hellbender populations varies from state to state, status ranks for most of the states within its range indicate that this salamander is in some degree of peril. Of the 16 states comprising the eastern hellbender’s range, nearly 88 percent consider populations to be “critically imperiled,” “imperiled,” or “vulnerable.” Of these about 33 percent have designated eastern hellbenders as endangered, thus providing legal protection. Land ownership information indicates that some eastern hellbender habitat is contained within federally or state owned areas (forests and parks). The remaining areas containing eastern hellbender habitat are privately owned. Conservation activities that benefit the species include water quality and habitat improvement efforts, funding programs, public outreach, and development of Best Management Practices (i.e. erosion control measures, re-vegetation of disturbed areas adjacent to streams, stream bank stabilization, and the establishment of stream management zones). Management actions and research needed to protect the species include a need to educate the public, especially fishing enthusiasts, about the hellbender’s harmless nature and threatened existence. A few states have developed and are implementing such outreach programs. There also appears to be a need to develop and enforce measures to prevent the collection of hellbenders for commercial (pet) trade. The need for increased monitoring and surveying of populations dominates the research priorities. More effort is needed to better understand current distributions as well as identify new populations. There is also a critical need for basic research featuring experimental designs and hypotheses that enable investigators to collect quantitative data on eastern hellbender population trends, and integrate them with data representative of potential threats. Both basic and applied research is needed to develop and refine captive breeding and reintroduction techniques.