Reticulate Whipray, Coach Whipray.
A large stingray with a kite-shaped disc that is slightly wider than long. Disc width 1-1.1 x length. Snout relatively short with an obtusely angular point. Anterior margins of disc mildly concave. Pectoral fin apexes narrowly rounded or somewhat angular.
Eyes small and protruding. Snout length 2.1-2.2 x combined eye and spiracle length.
Mouth usually contains 4 oral papillae; central papillae occasionally have small papillae between them. Prominent labial furrows and folds around mouth. Mouth slightly arched. Lower jaw concave at symphysis. Wide, short, skirt-shaped nasal curtain with a finely fringed posterior margin.
1-3 small heart-shaped thorns on central disc. Well developed denticle band (in adults) extends onto tail. Tail narrow-based, tapering evenly to caudal sting, then whiplike or filamentous to tip. Small, sharp thorns on tail beyond caudal sting. Tail length (when intact) 3-3.5 x disc width. Caudal folds absent. One caudal sting usually present.
Dorsum pale, tan, or greyish-brown with a dense pattern of small dark spots. Juveniles similarly similarly covered in small black spots. Subadults may display a reticulate pattern. Tail weakly banded beyond sting. Ventrum white.
Maximum disc width at least 160cm. Disc width at birth approximately 21-28cm.
Sub-tropical/tropical seas. On soft substrates, sometimes adjacent to reefs. From shallow estuaries to at least 50m. Known to enter freshwater.
Indian Ocean and west Pacific. Found from South Africa, Madagascar, East Africa, Red Sea, Persian Gulf, India, and Southeast Asia from The Philippines to Indonesia.
This assessment is does not yet recognize the division of H. uarnak and H. australis. Consequently, references to Australia should be disregarded until H. uarnak is proven to occur in Australian waters.
The Reticulate Whipray (Himantura uarnak) is taken as a utilised bycatch of tangle/gill net, trawl net, and dropline fisheries throughout Southeast Asia and parts of the Indian Ocean where inshore fishing pressure is intense. The Reticulate Whipray faces many of the same threats as other Himantura species within its range, however, its large size at maturity and maximum size, low fecundity and preference for shallow waters (which are being heavily utilised and degraded in many parts of its range), suggest that it may be more vulnerable than some of its congeners. It is caught in particularly high numbers in the target fishery for rhynchobatids operating in the Arafura Sea.
Although no species-specific data are available, overall catches of stingrays are reported to be declining, with fishermen having to travel further and further to sustain catch levels. Aggregated time series data for rays also shows a steady decline from 1973-1994 in the Gulf of Thailand. This species’ preference for inshore coastal waters means it is also threatened by extensive habitat degradation and destructive fishing practices throughout a large part of its range. Given the species’ high levels of exploitation, extensive habitat degradation and its large size, significant population declines are inferred to have occurred and are likely to be ongoing in Southeast Asia and more widely in the Indian Ocean. Conversely, this species has refuge from fishing pressure in northern Australia, where fishing pressure is light, bycatch mitigation measures are in place and it is not commercially utilised and consequently is considered at low risk.
Given the continuation of high levels of exploitation throughout most its range where the species is caught in multiple types of fisheries, along with evidence for declines in catches of rays, the level of decline (>30% over the last three generations) and exploitation can be inferred from overall declines in fish catches in the region, as well as from habitat loss. The Leopard Whipray is assessed as Vulnerable globally based on inferred levels of decline and exploitation across a large part of its range, but is considered to be Least Concern in Australia.
Manjaji Matsumoto, B.M., White, W.T. & Gutteridge, A.N. 2016. Himantura uarnak. The IUCN Red List of Threatened Species 2016: e.T161692A68629130. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T161692A68629130.en. Downloaded on 16 February 2021.
Matrotrophic aplacental viviparity. Two pups per litter.
Invertebrates and small benthic fishes.
Sedentary. Spends much of the day resting on the substrate.
Reaction to divers
Shy but approachable with non-aggressive movements. Generally bolts if approached closely.
Reticulate or coach whiprays are probably encountered at numerous dive sites throughout the Indian Ocean and southeast Asia but divers have a hard time identifying the four spotted himantura species from one another so advice on where to find reticulate whiprays is currently unavailable.
The problem of positive identification is exacerbated by the regional use of a variety of common names that are applied to different species in different areas. The following names are sometimes applied to all four himantura species: leopard whipray/stingray, reticulated whipray/stingray, coach whipray, and honeycomb whipray/stingray.
Within the area where reticulate or coach whiprays are probably present, at the Ad Dimaniyat Islands off the northeast coast of Oman, rays of the himantura species-complex are apparently abundant (Intel Christophe Chellapermal).