Not just a
huge collection of
Shark
Pictures:
Elasmodiver.com contains images of sharks, skates, rays, and a few
chimaera's from around the world. Elasmodiver began as a simple web
based
shark
field guide
to help divers find the best places to encounter the different
species of sharks and rays that live in shallow water but it has
slowly evolved into a much larger project containing information on
all aspects of shark diving and shark photography.
There are
now more than 10,000 shark pictures and sections on shark
evolution, biology, and conservation. There is a large library of
reviewed shark books, a constantly updated shark taxonomy page, a
monster list of shark links, and deeper in the site there are
numerous articles and stories about shark encounters. Elasmodiver is
now so difficult to check for updates, that new information and
pictures are listed on an Elasmodiver Updates Page that can be
accessed here:
Synonyms: Dasyatis
akejei, Trygon akejei. Some
scientists consider D.multispinosa to be a synonym also.
Family:
Dasyatidae.
Identification:
The red stingray has a rhomboid disc with
a triangular and slightly produced snout, straight anterior margins,
rounded free tips and convex posterior margins. The
dorsal surface of the body disc is uniformly reddish brown sometimes
lighter at the disc margin and around the eyes, spiracles and
laterally on the tail. Mature adults have tubercles on back and tail.
Ventral surface of disc white with yellow/orange or
dark margin.
Dorsal keel and ventral finfold present on tail. Tail
around 1.5 x length of body. Upper surface of tail has 1-3 stinging spines.
Filamental rear section of tail dark or black.
Size:
Maximum length with tail intact 200cm but
more commonly 100cm.
Habitat:
Found mostly on sand (sometimes adjacent to reefs) in
shallow coastal flats and bays below 10m.
Also on mud and in estuarine environments.
Distribution:
Restricted to the northwest Pacific.
Common from Okinawa to Hokkaido in Japan. Also
recorded from Korea, mainland China and Taiwan. Records from
Thailand, the Philippines, Fiji and Tuvalu may be erroneous
identifications. The range of the red stingray is currently under
review.
Diet:
Crustaceans, small bony fishes, annelid worms and
occasionally mollusks.
Reproduction:
Ovoviviparous. In
the somewhat antiquated 'Reef Sharks and Rays of the World' Scott
Michael lists the red stingray as having up to 10 pups per litter.
According to more recent observations by H. Ishihara, the red
stingray has a very low fecundity and gives birth to only one pup
per litter.
Conservation Status:
According to the IUCN, the red stingray is
subject to high fishing effort and is caught in commercial
quantities in the coastal waters of Japan and even in brackish
waters. It is taken as bycatch in the bottom trawl fishery, gillnet,
set net and hook and line fishery targeting demersal bottom fishes
such as flounders. This bycatch is utilized and landings are
reported to be declining. Fecundity is very low with one pup per
litter reported. Due to the current high level of bycatch and strong
fishing pressure in its area of occurrence, which will have depleted
the population, this species should be classified as Near
Threatened. Data need to be collected in order to accurately assess
the population status, which may show that the species falls into a
higher threat category.
Photographs:
Ito, Chiba Prefecture,
Japan.
Similar species:
There are two other
species of stingrays caught around Honshu Island in the Sea of
Japan that could be confused with the red stingray.
The
pitted stingray Dasyatis matsubarai has a dark gray
dorsum with a line of white spots on each pectoral fin. The Izu
stingray Dasyatis izuensis has a distinctively white caudal finfold.
Further afield, the red stingray could be confused
with the Pink or Tahitian stingray
Dasyatis fai which has a much longer caudal
filament (tail whip) and a uniformly pale ventrum.
Reaction to divers:
Probably skittish in a normal encounter but very easy to approach in
a baited situation - see below.
Diving Logistics:
The best place to encounter red stingrays is in
Ito, Japan where they are inadvertently baited in as part of a shark
feed designed to attract banded hound sharks. For more information
on this feed, contact Bigfishexpeditions.com
References and Citations:
Huveneers, C. & Ishihara, H. 2006. Dasyatis
akajei. The IUCN Red List of Threatened Species. Version 2015.1.
<www.iucnredlist.org>.
