Lost shark
A possibly extinct requiem shark known from only three old specimens.
The lost shark (Carcharhinus obsoletus), once called the false smalltail shark, is a requiem shark that may already be extinct. Scientists know it only from the southern South China Sea, in the western Central Pacific Ocean. Just three specimens have ever been found, collected in Borneo, Vietnam, and Thailand more than 80 years ago. These were first thought to be smalltail sharks (Carcharhinus porosus), but subtle differences in body shape—especially the placement of the second dorsal and anal fins, and a low number of vertebrae—showed they were a separate species, initially labeled *Carcharhinus* sp. A. Because no one has seen one in over eight decades, the lost shark is listed as Critically Endangered or Possibly Extinct on the IUCN Red List (as of 2020). Like other sharks in the *C. porosus* group, it probably had low reproductive rates and lived in shallow waters where fishing is easy, making it highly vulnerable to overfishing. Still, the rediscovery of the Borneo shark in 2004 after a long absence gives some hope that the lost shark might still survive somewhere.
Quick Facts
- Taxon
- Carcharhinus obsoletus
Facts from the source article.
Lore & Background
The lost shark is known only from three specimens collected in Borneo, Vietnam, and Thailand, all of which are over 80 years old. These specimens were originally tentatively assigned to the smalltail shark (Carcharhinus porosus), but subtle morphometric differences revealed they belonged to a new species, initially referred to as Carcharhinus sp. A. It differs from other Carcharhinus species by the relative position of the second dorsal and anal fins, as well as its low vertebral count.
As no individuals have been identified for over 80 years, the species may be extinct. Like other members of the C. porosus subgroup, it likely had limited fecundity and lived in shallow waters easily accessed by fishermen, putting it at heavy risk of extinction from overfishing. However, the rediscovery of the Borneo shark (Carcharhinus borneensis) in 2004 after a long period of no sightings has kept hopes for its possible survival.
Reader's Guide
The lost shark's significance lies in its extreme rarity and the uncertainty surrounding its existence. With only three historical specimens known, it represents one of the most poorly documented shark species. Its possible extinction highlights the vulnerability of shallow-water requiem sharks, particularly those with limited fecundity, to overfishing. The species was originally misidentified as the smalltail shark, and only careful morphometric analysis revealed its distinctness. The 2020 IUCN Red List designation as Critically Endangered or Possibly Extinct underscores the lack of evidence for survival, yet the rediscovery of the Borneo shark in 2004 after a long absence provides a cautious hope that the lost shark might still persist undetected. Its legacy is a reminder of how little is known about some marine species and the urgent need for surveys in its known range.
Did You Know?
- The lost shark was previously known as the false smalltail shark.
- Only three specimens of the lost shark are known, all over 80 years old.
- The IUCN Red List declared the lost shark to be Critically Endangered or Possibly Extinct in 2020.
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