|Scientific Name:||Rhinobatos schlegelii|
|Species Authority:||Müller & Henle, 1841|
|Taxonomic Notes:||There are significant problems with the systematics of the ?Rhinobatos schlegelii? group. Rhinobatos schlegelii was described from Japan and maybe a possible Northwest Pacific endemic. There are nominal records from China, Taiwan and Korea and an uncertain record from Viet Nam.
There are short-snouted and long-snouted forms of the species from Japanese waters and critical examination of these is required. These two forms may represent sexual dimorphism or may represent separate species. If the two are separate species in Japanese waters the records of nominal R. schlegelii from China, Taiwan and Korea need to be assessed to determine if one or both forms occur there.
A further undescribed form exists from the Philippines and this is not conspecific with R. schlegelii (Compagno et al. 2005). Further records of ?R. schlegelii? from India and Oman represent other species (Compagno and Last 1999).
Existing literature on ?R. schlegelii? is unreliable for these reasons.
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Compagno, L.J.V. & Ishihara, H.|
|Reviewer(s):||Kyne, P.M., Fowler, S.L. & Valenti, S.V. (Shark Red List Authority)|
The Brown Guitarfish (Rhinobatos schlegelii) was described from Japan and may be endemic to northwest Pacific waters. There are significant problems with the systematics of the Rhinobatos schlegelii group. This species is known from nominal records from China, Taiwan and Korea and an uncertain record from Viet Nam. Reports from other areas represent other species. It is susceptible to capture in a variety of fishing gear including trawl, gillnet and line fisheries and rhinobatids are highly valued for their fins. Historical fishing pressure has been relatively intensive across its known range, although increases in fuel prices have reportedly led to some decrease in recent years off Japan. Other Rhinobatos species have proved vulnerable to population depletion as a result of their limiting life-history characteristics and serious declines have been reported in similar species where they are heavily fished. Taxonomic uncertainty and a lack of trend data mean that this species is currently assessed as Data Deficient, although it may prove to be threatened when these issues are resolved.
|Range Description:||Possibly endemic to the northwest Pacific, centered off Japanese Archipelago. From Ibaragi and Niigata Prefecture, Japan south to the East China Sea and South China Sea (Yamada et al. 2007). See Taxonomy section for further details.|
Native:China (Shanghai); Japan; Korea, Democratic People's Republic of; Korea, Republic of; Taiwan, Province of China (Taiwan, Province of China (main island))
|FAO Marine Fishing Areas:||
Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No specific data are available on temporal population trends, Due to heavy fishing and bycatch pressures throughout its range this species is suspected to be declining.|
|Habitat and Ecology:||Benthic in inshore habitats, reported at depths of 80-230 m. Attains a maximum size of 97 cm total length (TL) (Yamada et al. 2007). Reproduction is aplacental viviparous with litter sizes from 2-7 pups and a gestation period of 12 months (Yamada et al. 2007). Diet consists of fishes, shrimps and cephalopods.|
Like other rhinobatids, this species' biology makes it highly susceptible to population depletion. It is susceptible to capture in a variety of fishing gear including trawl, gillnet, and line. Net and line fisheries operate over much of the known range of this species and as such it is impacted by direct and indirect fishing pressure and landed where the flesh is utilised. It is unlikely to withstand the present level of fishing pressure across its range and habitat. This level of pressure will increase in the future as areas of the northwest Pacific are more heavily exploited due to an increasing human population and expanding global fisheries.
Habitat requirements are not well understood, but inshore areas are important as nursery areas for Rhinobatos species and these are being impacted upon by fishing activities and environmental degradation/pollution.
Historical fishing pressure is generally intensive in the northwest Pacific (NOAA 2004ab). However, increases in fuel prices have reportedly led to some decrease in fishing activities in recent years off Japan (H. Ishihara pers. obs. 2007).
In the first instance, taxonomic issues need to be resolved. This will allow accurate mapping of the species' range.
There is a need to acquire accurate catch data from fisheries throughout the species' distribution. Better understanding of habitat requirements and critical area/habitats is required to establish best amelioration processes.
Future management will need to consider harvest and trade management with a focus on resource stewardship and livelihood alternatives.
The development and implementation of management plans (national and/or regional e.g. under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) are required to facilitate the conservation and management of all elasmobranch species. See Anon. (2004) for an update of progress made towards development and implementation of National Plans of Action for countries across the range of
|Citation:||Compagno, L.J.V. & Ishihara, H. 2009. Rhinobatos schlegelii. The IUCN Red List of Threatened Species. Version 2014.1. <www.iucnredlist.org>. Downloaded on 23 July 2014.|
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