In 1973, researchers scientifically described a species of shark based on a single specimen: a pregnant female caught a few years earlier by a fisherman near the mouth of the Gogol River in Astrolabe Bay, Papua New Guinea. They named this new-to-science species the sailback houndshark (Gogolia filewoodi). And then, for the next half-century, they didn’t see another one.

Now, however, researchers have confirmed in a new study that there are still sailback houndsharks in the area, occasionally getting caught in fishing gear.

The researchers from WWF interviewed fishers and conducted surveys of fish markets in Papua New Guinea’s Madang province. They recorded five female sailback houndsharks that a fisher had caught near the mouth of the Gogol River over the course of just two days in March 2020. The individuals were captured close to where the initial specimen was caught in 1970.

Two years later, in September 2022, another fisher caught the first recorded adult male of the species, again near the mouth of the Gogol.

Both fishers were targeting jewfish, and caught the sailback houndsharks incidentally. The shark itself isn’t a target because its meat isn’t popular and its fins aren’t considered good enough for the shark-fin trade, several fishers in the area said.

They added they occasionally net the shark as bycatch while targeting jewfish. The fishers seek jewfish mainly for the fish maw, or swim bladder, typically in demand from March to July and August to November. Dried fish maw is considered a culinary delicacy across East and Southeast Asia.

The fish maw fishery is a major pressure on threatened species of sawfish (family Pristidae), river sharks (genus Glyphis) and winghead sharks (Eusphyra blochii) in southern PNG, the researchers write. In Astrolabe Bay, they add, “growing interest in the fish maw trade could be an imminent threat” to the sailback houndshark.

This is because the species appears to be rare and “micro-endemic” to the Gogol River’s mouth. It hasn’t turned up in previous marine surveys of the region, and the new records were all close to where the first specimen was caught 55 years ago, suggesting its geographic range is possibly restricted to a small region around Astrolabe Bay. This limited distribution makes the shark particularly vulnerable to increases in fishing pressure in the future, the researchers note.

The sailback houndshark is currently listed as data deficient on the IUCN Red List. Despite the latest records of the species, its distribution, ecology and life history still remain largely unknown.

Banner image: An adult female (top) and male (bottom) sailback houndsharks caught near the mouth of the Gogol River. Image courtesy of Sagumai et al., 2025 (CC BY 4.0).