Some marine species appear once – and then vanish for decades. One of them is the sailback houndshark, a rare shark with an unusually tall dorsal fin. It was first described in 1973, after a pregnant female was caught near the Gogol River in Astrolabe Bay (Papua New Guinea). For fifty years, this specimen remained the only record.
Return to the discovery site: photos confirm surviving population
In March 2020, researchers together with local fishers found new evidence: several photographs showed sharks with a strikingly tall dorsal fin – five females, clearly identifiable as the long-lost sailback houndshark. Two years later, a male was documented in the same region for the first time. This confirms that the species still exists – and continues to inhabit the waters of Papua New Guinea today.
Bycatch rather than target species – and of little value on the market
Fishers in Astrolabe Bay report that the species is occasionally caught as bycatch, mainly during the capture of “jewfish” for the lucrative fish maw trade. Most catches occur between March and July and again in the dry season from August to November. The meat has little local value, and the fins are considered low-grade for the fin trade.
Extremely small range
All recent records come from near the mouth of the Gogol River. The shark apparently prefers deeper areas along the narrow continental shelf – and there it encounters small-scale fishers. The strong concentration of findings in Astrolabe Bay points to microendemism, meaning a very limited distribution.
Some researchers suspect that the species was once more widespread – perhaps extending beyond Papua New Guinea to Indonesia. Today, only “a last small remnant population” may remain, says shark researcher David Ebert.
Threats: overfishing and habitat pressure
As with many sharks and rays, overfishing and habitat loss are among the greatest risks. Even without targeted fishing, regular bycatch can quickly endanger a species with a small population – especially when its range is so narrowly limited.
Scientific value and next steps
The sailback houndshark represents an independent evolutionary line within the triakids and is therefore of great scientific interest. Two preserved specimens are kept at the University of Papua New Guinea; together with partners in Australia and Florida, DNA analyses are planned to provide a genetic basis for future monitoring.
“These efforts create a genetic baseline and help develop conservation strategies,” says Jack Sagumai, lead author of the study.
Symbol of protection and cooperation
The rediscovery after half a century brings hope – and also serves as a warning. Such a rare, locally restricted species can vanish unnoticed. Science, conservation measures and the knowledge of local communities must work together to turn a curious rediscovery into lasting protection. The study was published in the Journal of Fish Biology.
