Rare shark rediscovered after 50 years

The ocean is full of enigmas, guarding species that appear once and vanish for decades. One such case is the sailback houndshark, a rare shark distinguished by its unusually tall dorsal fin.

The shark was first described in 1973 after a pregnant female was caught near the Gogol River in Papua New Guinea’s Astrolabe Bay. For 50 years, this single specimen was the only evidence of its existence.

Sailback houndshark rediscovered

In March 2020, researchers collaborating with local fishing communities came across a remarkable discovery. Fishers near the mouth of the Gogol River shared photographs of several unusual sharks, each with a strikingly tall dorsal fin.

Upon closer examination, the images revealed five female sharks, all belonging to the long-lost sailback houndshark.

For decades, this species had only been known from a single specimen collected in the early 1970s. The 2020 sighting marked the first confirmed evidence that the species still survived in the wild.

Two years later, the discovery of a male in the same area further strengthened the finding, proving that this rare shark was not extinct but quietly persisting in the waters of Papua New Guinea.

Fishers spot sailback houndshark

While science had no records for decades, fishers in Astrolabe Bay occasionally encountered the species.

Reports suggest the sharks are caught incidentally while targeting jewfish for the lucrative fish maw trade.

Most captures occur between March and July, and again in the dry season from August to November. Unlike other sharks, their meat is not valued locally and is often given away, while their fins are of poor quality for the fin trade.

A species with limits

Surveys confirm that all modern records come from near the Gogol River mouth. The shark appears to prefer deeper waters close to the continental shelf, which is narrow in this part of Papua New Guinea.

These deeper trenches bring the species into contact with small-scale fishers. Its apparent restriction to Astrolabe Bay suggests it may be microendemic, existing only in this limited area.

Some researchers believe its distribution may once have stretched further, across Papua New Guinea and perhaps even Indonesia. As David Ebert notes, it might now be reduced to “this last little remnant population.”

Such contractions have parallels with other local shark species, including bamboo and epaulette sharks, that are also confined to small habitats.

Sailback houndshark under threat

Overfishing and habitat pressures are among the biggest threats to sharks and rays worldwide. For the sailback houndshark, rising demand for fish maw presents a serious risk.

Even if not directly targeted, regular bycatch could jeopardize its survival. Rare species with such limited ranges face heightened vulnerability when human activity intensifies.

Significance of the shark

The sailback houndshark represents a unique evolutionary lineage within the triakid sharks, making it of high scientific interest.

Two preserved specimens are now held at the University of Papua New Guinea, where researchers are preparing DNA analyses with colleagues in Australia and Florida.

“These efforts will help create a genetic baseline for future monitoring and guide protection strategies,” said Jack Sagumai, first author of a study describing the discovery.

Saving the sailback houndshark

The rediscovery of the sailback houndshark after fifty years is both inspiring and concerning. On one hand, it shows that this rare species has managed to survive despite decades without a scientific record, offering hope that other elusive marine animals might still be found.

On the other hand, its rarity and restricted range reveal how vulnerable it is to threats such as overfishing and habitat pressures. A species can vanish quietly when its population is small and localized, making urgent action essential.

By combining scientific research, conservation strategies, and the knowledge of local communities, this shark has the potential to be more than just a rediscovered curiosity.

It could become a powerful emblem of Papua New Guinea’s unique marine biodiversity and the importance of protecting fragile ecosystems before they are lost forever.

The study is published in the Journal of Fish Biology.

Image Credit: Jack Sagumai et al. (2025)

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