''Brevitrygon walga'', the dwarf whipray or mangrove whipray, is a small stingray, a
cartilaginous fish
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue ...
in the
family Dasyatidae. It is a
demersal
The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...
fish and is found over the continental and insular shelf of the west central Pacific Ocean where it is heavily fished. The
IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
has assessed it as being "
near-threatened".
Description
The dwarf whipray has a maximum length of .
[ The disc width is commonly about .]
Distribution and habitat
The dwarf whipray is found in the western central Pacific Ocean. Its range extends from Thailand, Cambodia and Vietnam to Singapore, Malaysia, the Philippines and Indonesia. It has been recorded from India, but may have been confused there with the scaly whipray
The ''scaly whipray'' or Bengal whipray, (''Brevitrygon imbricata'') is a species of stingray in the family Dasyatidae, found in the tropical Indo-West Pacific oceans from the Red Sea and Mauritius to Indonesia. Its width is up to , and ...
(''Brevitrygon imbricata''). It occurs close to the sandy seabed on the inner continental shelf
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...
at depths usually less than .
Biology
The dwarf whipray reaches maturity at a length of about . Mating occurs when the male grasps the female with their ventral surfaces in contact. This fish is viviparous, giving birth to one or two young at a time. The gestation period
In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once it ...
is not known, but before birth, the pups are fed on secretions from the uterine wall, a process known as histotrophy.
Use
The dwarf whipray is caught, largely as bycatch
Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...
, over most of its wide range. Trawling for batoids is common in many places and trammel netting, in which the fish get entangled in the fine-meshed central net of a three-part net, is used over much of its range. The fish is used for human consumption, but is not specifically targeted, probably because of its small size.
Status
The International Union for Conservation of Nature has assessed the conservation status of the dwarf whipray as being " near-threatened". The organisation considers the fish is experiencing intense fishing pressure over much of its range and is being over-exploited. Its abundance appears to be falling and the size of the fish caught also seems to be declining.
References
{{Taxonbar, from=Q11925647
dwarf whipray
Fish of the Indian Ocean
Marine fauna of South Asia
dwarf whipray