As primitive, tubelike scavengers that feed on dead and dying animals, hagfish are hardly charismatic or appealing, so the discovery that at least 12 percent of hagfish species face an elevated risk of extinction may not tug on the heartstrings.
But conservationists are concerned.
"Hagfish are a great example of one of those 'not-so-cute' species that play a vital role in ecosystem health," said Cristiane Elfes, a program officer with a unit of the Global Marine Species Assessment, a joint initiative of several groups. The study was produced as part of this initiative. "This study highlights the impact we have on hagfish and the importance of protecting them to maintain the stability of ocean ecosystems."
The study indicates that fishing is the primary direct and indirect cause of hagfish declines: Hagfish are caught intentionally for food and leather, and they also get scooped up unintentionally in bottom-trawling nets that damage their habitat on the seafloor. [Oceans Primed for Mass Extinction?]
The study found that of 76 species of hagfish worldwide, nine qualified under criteria by the International Union for Conservation of Nature (IUCN) as critically endangered to vulnerable, while two more qualified as near threatened. Because of a lack of information on existing numbers, 30 species could not be categorized. Particular areas of concern include the waters off southern Australia, southern Brazil, the Pacific coast of Japan and the coast of Taiwan, as well as in the East China Sea, according to the study.
In addition to having gruesome table manners — one study suggests they absorb nutrients through their skin when burrowing into dead and dying animals — hagfish play a crucial role in ecosystems by cleaning the ocean floor and recycling nutrients.
"The presence of hagfish in areas of intense fishing is extremely important as large amounts of bycatch are discarded," said Landon Knapp, research assistant for the IUCN Marine Biodiversity Unit at Old Dominion University in Virginia and lead author of the study. Bycatch refers to animals caught unintentionally during fishing.
In addition to working as clean-up crew, hagfish are also important prey for fish, seabirds and marine mammals. Stock of other commercial species, such as flounder, plummeted when fishing pressure focused on hagfish in certain locations in the northwest Atlantic Ocean.
The study, authored by researchers at Old Dominion University and Universidade Federal do Rio de Janeiro in Brazil, appears in the journal Aquatic Conservation: Marine and Freshwater Ecosystems.
It is part of the Global Marine Species Assessment, a joint initiative of IUCN, Conservation International and Old Dominion University, which has been working since 2005 to provide assessments for more than 20,000 species.
You can follow LiveScience writer Wynne Parry on Twitter @Wynne_Parry.
