|Scientific Name:||Eptatretus okinoseanus|
|Species Authority:||(Dean, 1904)|
Homea okinoseana Dean, 1904
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Mincarone, M.M. & Mok, H.-K.|
|Reviewer(s):||Polidoro, B., Knapp, L. & Carpenter, K.E.|
This species is widespread in deeper waters off of the coast of Japan and Taiwan. There are no known threats to this species. However, it is likely caught incidentally in bottom trawling fisheries in the majority of its range. It is listed as Least Concern. More research is needed on this species distribution, population, biology, life history, and potential threats. While records suggest that this species is wide ranging, further surveys are necessary to confirm presence along the east coast of Japan and across the Okinawa Trough.
|Range Description:||This species is found off of eastern and southern Honshu Island (Japan), Okinawa Trough, and northeast Taiwan.|
Native:Japan (Honshu); Taiwan, Province of China
|FAO Marine Fishing Areas:||
Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The population data for this species is based on recordings this are currently assumed to be wide ranging species, but population abundance levels are unknown. The sampling size is still insufficient to understand abundance and distribution.|
|Habitat and Ecology:||
This species occurs on slopes at depths from 300-1,020 m. On the Okinawa Trough it was reported among rocks on the Iheya Ridge, near a hydrothermal vent (Ohta and Kim 2001). An 800 mm female reported by Dean (1904) had 44 well-developed eggs, with an average size of 32x12 mm.
The copulatory organ is absent for 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):||This species is not targeted for food or leather markets but its depth and 80% of its distribution range overlaps with bottom trawling activities so is susceptible, with its large body size, to incidental bycatch.|
|Conservation Actions:||There are no conservation measures in place for this species, but more research is needed on the species' biology, population size, distribution and impact bottom trawling activities along the east coast of Japan.|
Adam, H. and Strahan, R. 1963. Systematics and geographical distribution of myxinoids. In: A. Brodal and R. Fänge (eds), The biology of Myxine, pp. 588. Universitetsforlaget, Oslo.
Dean, B. 1904. Notes on Japanese myxinoids. A new genus, Paramyxine, and a new species, Homea okinoseana, reference also to their eggs. The Journal of the College of Science, Imperial University of Tokyo 19: 1-23.
IUCN. 2011. IUCN Red List of Threatened Species (ver. 2011.1). Available at: http://www.iucnredlist.org. (Accessed: 16 June 2011).
Ohta, S. and Kim, D. 2001. Submersible observations of the hydrothermal vent communities on the Iheya ridge, mid Okinawa Trough, Japan. Journal of Oceanography 57: 663-677.
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. & Mok, H.-K. 2013. Eptatretus okinoseanus. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 30 June 2015.|