|Scientific Name:||Eptatretus hexatrema|
|Species Authority:||(Müller, 1836)|
Bdellostoma heterotrema Müller, 1836
Bdellostoma hexatrema Müller, 1836
Bdellostoma-hexatrema was briefly described by Müller (1836) as having six gill apertures on both left and right sides. Based on this character, he also described Bdellostoma heterotrema, which had seven and six gill apertures on the left and right sides, respectively. However, in some specimens of hexatrema, the last branchial duct is not confluent with the pharyngocutaneous duct on the left side. This is the case of the type of Bdellostoma heterotrema, which has six gill apertures plus the pharyngocutaneous opening on the left side.
In the second part of his work, Müller (1838) believed that all the species described by him in 1836, including Bdellostoma heptatrema from southern seas, were just simple varieties of Bdellostoma forsteri (Müller, 1836) (junior synonym of Eptatretus cirrhatus). Recently, the combinations Bdellostoma forsteri var. heterotrema and Bdellostoma forsteri var. hexatrema were treated incorrectly as original descriptions in Müller (1838) by Paepke and Schmidt (1988).
|Red List Category & Criteria:||Least Concern ver 3.1|
|Reviewer(s):||Polidoro, B., Knapp, L. & Carpenter, K.E.|
This species is only known from southern Africa, where it is considered common throughout its range. At least 80% of this species range is subject to hake trawling activities that are directly impacting quality of habitat across its depth range. It is listed as Least Concern. However, close attention and increased monitoring of this species should be considered.
|Range Description:||This species is known from southern Africa, from Walvis Bay (Namibia) to Durban (Natal).|
Native:Namibia; South Africa
|FAO Marine Fishing Areas:||
Atlantic – southeast; Indian Ocean – western
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species is known to be a common species but there is little understanding of its population levels. This is likely to be the most abundant species of Hagfish along the South Africa coast.|
|Habitat and Ecology:||
This species is located on muddy bottoms of the continental shelf and slope at depths from 12-400 m.
This species commonly burrows in muddy bottoms. It feeds mostly by scavenging on dead or disabled fish (Bianchi et al. 1993). The copulatory organ is absent in this species. The gonads of hagfishes are situated in the peritoneal cavity. The ovary is found in the anterior portion of the gonad, and the testis is found in the posterior part. The animal becomes female if the cranial part of the gonad develops or male if the caudal part undergoes differentiation. If none develops, then the animal becomes sterile. If both anterior and posterior parts develop, then the animal becomes a functional hermaphrodite. However, hermaphroditism being characterised as functional needs to be validated by more reproduction studies (Patzner 1998).
|Major Threat(s):||There are no known direct threats to this species, but full species' distribution range directly overlaps with hake trawling activities. The fishery extends well into Namibia on the west coast and is destructive to this species' habitat as well as it being incidentally caught as by-catch. This species is also exposed to coastal pressures as its depth range extends up to 12 meters.|
|Conservation Actions:||There are no conservation measures in place, but more research is needed on this species' biology, population size and the impact of the Hake fishery on population levels and habitat.|
Bianchi, G., Carpenter, K.E., Roux, J.-P., Molloy, F.J., Boyer, D., and Boyer, H.J. 1993. FAO species identification field guide for fishery purposes. The living marine resources of Namibia. FAO, Rome.
Fernholm, B. 1986. Myxinidae. In: M.M. Smith and P.C. Heemstra (eds), Smiths’ sea fishes, pp. 35-36. Macmillan, Johannesburg.
IUCN. 2011. IUCN Red List of Threatened Species (ver. 2011.1). Available at: http://www.iucnredlist.org. (Accessed: 16 June 2011).
Müller, J. 1836. Vergleichende Anatomie der Myxinoiden, der Cyclostomen mit durchbohrtem Gaumen. Erster Theil. Osteologie und Myologie., pp. 65-340. Abh. Königl. Akad. Wiss, Berlin.
Müller, J. 1838. Vergleichende Anatomie der Myxinoiden. Vergleichende Neurologie der Myxinoiden., pp. 171-251. Abh. Königl. Akad. Wiss, Berlin.
Paepke, H.-J. and Schmidt, K. 1988. Kritischer katalog der typen der fischsammlung des Zoologischen Museums Berlin. Teil 2: Agnatha, Chondrichthyes. Mitteilungen aus dem Zoologischen Museum in Berlin 64(1): 155-189.
Patzner, R.A. 1998. Gonads and reproduction in hagfishes. In: J.M. Jørgensen, J.P. Lomholt, R.E. Weber, and H. Malte (eds), The biology of hagfishes, pp. 378-395. Chapman & Hall, London.
|Citation:||Mincarone, M.M. 2013. Eptatretus hexatrema. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 July 2014.|