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Five decades ago, a single description of the rare sailback houndshark was recorded. The pregnant shark, captured by a fisherman, was small with a wide mouth, short snout, large eyes, and a dorsal fin that resembled a sail on a boat. Scientists named the species Gogolia filewoodi, or the Sailback Houndshark, and it was never seen by scientists again. The assumption was that the already-rare animal had been overfished, but five full decades later, the small shark species has popped back up again in the same region it was originally discovered.
A new study published this week has verified five female sailback houndsharks caught in March 2020 by a fisherman near the mouth of Papua New Guinea’s Gogol River, which drains into Astrolabe Bay. Two years later, another local fisherman caught another sailback houndshark in the same area. This time it was a male, making it the first male of the species ever recorded.
“Anecdotal reports from fishers in Bilbil village and within Madang Lagoon indicate that the species is caught occasionally when fishing within Astrolabe Bay,” they write. “Despite their fishing activity extending throughout Astrolabe Bay and adjacent coast, all observed interactions with G. filewoodi occurred in Astrolabe Bay, close to the Gogol River mouth.”
The researchers also noted that local fishers don’t seem to target the sailbacks specifically, pointing out that their “flesh is not well regarded and often given away if in surplus … and the fins are not high quality for the shark fin trade.” They are calling it a “microendemic” species since as far as scientists know, it can only be found in this one part of the world.
Microendemic species are particularly vulnerable to extinction because any changes in their small, very specific habitat can have profound impacts.
“Rare and endemic species are vulnerable to extinction due to their limited distribution range and increasing anthropogenic threats in their habitats,” they wrote. “Despite the present scientific rediscovery, fundamental information is still lacking on its ecology, life history and distribution.”