Brevitrygon walga
A small, heavily fished stingray of the west central Pacific.
Brevitrygon walga, also called the dwarf whipray or mangrove whipray, is a small stingray belonging to the family Dasyatidae. This bottom-dwelling fish lives over the continental and insular shelves of the west central Pacific Ocean, where it faces heavy fishing pressure. The IUCN lists it as near-threatened.
The dwarf whipray reaches a maximum length of 45 cm, with a typical disc width of about 24 cm. Its body is oval in shape with a bluntly pointed snout. The whip-like tail is longer than the body and lacks the skin fold seen in some related species. Females have a shorter tail than males, ending in a bulbous tip. Both sexes have four to six erectile, venomous spines near the base of the tail. The fish is a uniform pinkish or beige color and, in turbid water, has been mistaken for a horseshoe crab.
This species occurs in the western central Pacific, from Thailand, Cambodia, and Vietnam to Singapore, Malaysia, the Philippines, and Indonesia. It has also been recorded in India, though those sightings may actually be the scaly whipray (Brevitrygon imbricata). It lives close to the sandy seabed on the inner continental shelf, usually at depths less than 50 m.
The dwarf whipray reaches maturity at about 17 cm in length. Mating involves the male grasping the female with their ventral surfaces in contact. It is viviparous, giving birth to one or two young at a time. The gestation period is unknown, but before birth, the pups are nourished by secretions from the uterine wall, a process called histotrophy.
Over most of its wide range, the dwarf whipray is caught largely as bycatch. Trawling for batoids is common in many areas, and trammel netting—where fish become entangled in the fine-meshed central net of a three-part net—is used extensively. Because of its small size, it is not specifically targeted but is used for human consumption.
The IUCN considers the dwarf whipray near-threatened. The organization notes that the fish faces intense fishing pressure across much of its range and is being overexploited. Its abundance appears to be declining, and the size of individuals caught also seems to be shrinking.
Quick Facts
- Taxon
- Brevitrygon walga
Facts from the source article.
Lore & Background
The dwarf whipray has an oval disc with a bluntly-pointed snout and a whip-like tail longer than its body, lacking the skin fold seen in some related species. Females have a shorter tail than males, with a bulbous tip, and both sexes possess four to six erectile, venomous spines at the base of the tail. Its uniform pinkish or beige colour has led to it being mistaken for a horseshoe crab in turbid water.
Its range extends from Thailand, Cambodia and Vietnam to Singapore, Malaysia, the Philippines and Indonesia; records from India may be confusions with the scaly whipray (Brevitrygon imbricata). It occurs close to the sandy seabed on the inner continental shelf at depths usually less than 50 m. The species reaches maturity at about 17 cm length, and mating involves the male grasping the female with their ventral surfaces in contact. It is viviparous, giving birth to one or two young, with the pups fed on uterine secretions (histotrophy) before birth.
The dwarf whipray is caught largely as bycatch over most of its wide range, primarily through trawling for batoids and trammel netting. It is used for human consumption but is not specifically targeted, probably due to its small size.
Reader's Guide
The dwarf whipray is notable as a small, heavily exploited stingray whose conservation status reflects intense fishing pressure across its range. The IUCN has assessed it as near-threatened, citing over-exploitation and declining abundance, as well as a decrease in the size of individuals caught. Its capture occurs largely as bycatch in trawl and trammel net fisheries, and despite being used for human consumption, it is not specifically targeted, likely because of its small size. The species' wide distribution in the west central Pacific, from Thailand to Indonesia, does not shield it from these pressures. The uncertainty regarding records from India, where it may be confused with the scaly whipray, highlights the need for careful taxonomic distinction. Overall, the dwarf whipray exemplifies the vulnerability of small, demersal batoids to unregulated fishing and serves as a case study for the challenges of managing bycatch species in tropical shelf fisheries.
Did You Know?
- The dwarf whipray has a maximum length of 45 cm (18 in).
- It has been mistaken for a horseshoe crab in turbid water due to its uniform pinkish or beige colour.
- The IUCN has assessed it as near-threatened due to intense fishing pressure and over-exploitation.
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