Depletion of the body snatchers: bad news for marine environment

IUCN 28 Jul 11;

A recent study conducted for The IUCN Red List of Threatened Species™ has determined that 20% of hagfish species are at an elevated risk of extinction*. Scientists warn that this figure could be much higher.

The results of this research, carried out in association with Conservation International (CI), indicate that the primary causes of hagfish declines are the direct and indirect effects of fisheries.

Hagfish represent an ancient and unique evolutionary lineage; as bottom feeders they play an important role by cleaning the ocean floor and recycling nutrients into the food web which maintains the overall health of the ecosystems they inhabit.

“By consuming the dead and decaying carcasses that have fallen to the ocean floor, hagfish clean the floor creating a rich environment for other species including commercial fish such as cod, haddock and flounder,” says Landon Knapp, research assistant for the IUCN Marine Biodiversity Unit at Old Dominion University and lead author of the study. “The presence of hagfish in areas of intense fishing is extremely important as large amounts of bycatch are discarded."

Particular areas of concern highlighted in the study include southern Australia, where the only hagfish species present is threatened, and the coast of southern Brazil. Also of concern are the species found in the East China Sea, the Pacific coast of Japan, and coastal Taiwan; in these areas, four of the 13 hagfish species occurring are threatened with extinction.

“In many geographic regions, only one or two hagfish species are present, and therefore the loss or decline of even a single species in these areas will have detrimental effects on ecosystems as a whole, as well as the fisheries that depend on them,” says Dr Michael Mincarone, Professor of Zoology at Universidade Federal do Rio de Janeiro, an author of the study.

Fisheries worldwide directly profit from the harvesting of hagfish, such as Myxine garmani (Vulnerable) and Eptatretus burgeri (Near Threatened) for leather and food. Hagfish are also an important part of the food chain, being prey for fishes, seabirds and even marine mammals, including seals. When fishing pressure was focused on hagfish in certain locations in the north-western Atlantic, the stock of other commercial species, such as flounder, plummeted.

Overexploitation and destructive fishing practices are major threats to several hagfish species, including Myxine paucidens and Paramyxine taiwanae, both listed as Endangered. No current conservation measures or legislation exist to protect hagfish populations.

“Additional data is required and controls for the regulation and management of hagfish fisheries and other threats to hagfish populations are urgently needed to ensure the survival of these important species,” says Dr Kent Carpenter, Professor at Old Dominion University, manager of IUCN’s Marine Biodiversity Unit and an author of the paper.

“Hagfish are a great example of one of those ‘not-so-cute’ species that play a vital role in ecosystem health,” says Cristiane Elfes, Programme Officer for the CI-IUCN Biodiversity Assessment Unit. “This study highlights the impact we have on hagfish and the importance of protecting them to maintain the stability of ocean ecosystems.”

*For those groups that have been comprehensively assessed on the IUCN Red List, the percentage of threatened species can be calculated, but the actual number of threatened species is often uncertain because it is not known whether Data Deficient (DD) species are actually threatened or not. Therefore, the percentage presented above provides the best estimate of extinction risk for this group (excluding Extinct species), based on the assumption that Data Deficient (DD) species are equally threatened as data sufficient species. In other words, this is a mid-point figure within a range from x% threatened species (if all DD species are not threatened) to y% threatened species (if all DD species are threatened). Available evidence indicates that this is a best estimate.

For example, for hagfishes, 20% of species (excluding DD species) are threatened, although the precise figure is uncertain and could lie between 12% (if all DD species are not threatened) and 51% (if all DD species are threatened).

'Not-So-Cute' Hagfish Threatened
Wynne Parry LiveScience.com 29 Jul 11;

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.