Hagfish face an uncertain future
New study show serious declines, raising ecological worries
David Alderton |
July 29, 2011
|Click image to enlarge|
Fisheries worldwide directly profit from the harvesting of hagfish for leather and food. Photo courtesy: Linda Snook, National Oceanic and Atmospheric Administration (NOAA) / Cordell Bank National Marine Sanctuary (CBNMS).
Hagfish represent a unique and ancient group of some 76 surviving species. They are the only living animals that have a skull but no vertebral column, and so are not true vertebrates. Their ancestry extends right back in the fossil record for at least 550 million years, making them one of the oldest surviving life forms on the planet.
Partly thanks to their appearance, hagfish are sometimes described as slime eels. This is also because they will produce large quantities of slime as a defensive measure if they are threatened.
Much still remains to be learned about them and their biology, but now, a recently-published study has confirmed that hagfish populations generally are under serious threat. At least 20 percent of species are regarded as being at an elevated risk of extinction, with some scientists warning that this figure could actually be much higher.
The results of this latest 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. As bottom feeders and scavengers, hagfish play an important role in cleaning the ocean floor and recycling nutrients into the food web, thereby maintaining the overall health of the ecosystems they inhabit.
Important In Marine Ecosystems
"By consuming the dead and decaying carcasses that have fallen to the ocean floor, hagfish clean this area, 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, Norfolk, Virginia and lead author of the study. "The presence of hagfish in areas of intense fishing is extremely important as large amounts of by-catch are typically 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, along the Pacific coast of Japan, and in coastal areas of Taiwan; in these localities, four of the 13 hagfish species present there 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," explains Dr. Michael Mincarone, Professor of Zoology at Universidade Federal do Rio de Janeiro, who was also involved in the study.
Overexploitation With No Protection
Fisheries worldwide directly profit from the harvesting of hagfish, such as Myxine garmani (classed as 'vulnerable') and Eptatretus burgeri (which is regarded as '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 of which are now endangered. Unfortunately, no current conservation measures or legislation exist to protect hagfish populations.
"Additional data are 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.
"Hagfish are a great example of one of those 'not-so-cute' species that nevertheless play a vital role in ecosystem health," adds Cristiane Elfes, Programme Officer for the CI-IUCN Biodiversity Assessment Unit. "This latest study highlights the impact we have on hagfish and the key importance of protecting them, in order to ensure the stability of our ocean ecosystems."
Reference: Conservation status of the world's hagfish species and the loss of phylogenetic diversity and ecosystem function can be found online here.
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Hagfish face an uncertain future