A string of extraordinarily rare deep-water discoveries has sent ripples of intrigue through the scientific community after a third elusive sixgill sawshark washed ashore near the Gulu River mouth last week.
The latest finding marks an unprecedented cluster of strandings along the Eastern Cape coastline within a single year, raising pressing questions about shifting ocean conditions and local marine dynamics.
The pristine, fresh specimen was discovered lodged near the shoreline by sharp-eyed local resident Chad Schenk.
Recognising the unusual nature of the creature, Schenk secured the specimen before local resident Cathrine Prentis and reported it to the East London Museum on Tuesday.
Principal natural scientist Kevin Cole swiftly traveled to the site to retrieve the shark for the museum’s marine biodiversity collection.
What makes the discovery exceptionally notable to marine biologists is the shark’s unique anatomical make-up.
While standard shark species universally possess five pairs of gill slits, the sixgill sawshark (Pliotrema) features six separate gill openings.
The bottom-dwelling ocean resident is equally famous for its long, flattened, saw-like snout (rostrum) lined with razor-sharp rostral teeth, accompanied by sensory barbels used to locate prey buried along the ocean floor.
Remarkably, last week’s recovery represents the second time in less than a month that the museum has acquired one of these rare ocean residents.
On August 24, Cosy Corner resident Moyra Meyer alerted researchers to another dead specimen along the shore, which was successfully secured and donated.
Speaking to the Go! on Wednesday, Cole highlighted that a cluster of three separate strandings within a few short months is virtually unheard of for the region, noting an earlier March 2026 discovery at the Mtati River mouth reported by visitor Astrid Verkerk.
Before 2026, the museum had not recorded a sixgill sawshark stranding since August 2021.
“So, to date, three records of sixgill sawsharks for 2026!” Cole said.
“Our last record prior to 2026 was a sixgill sawshark from Igoda in August 2021. To have three in a single year and two within less than a month is very uncommon.”
The sudden surge in strandings along local beaches has prompted naturalists to examine whether the species is far more abundant off the Eastern Cape coast than historical data suggests, or if shifting environmental conditions are forcing these deep-water creatures out of their natural habitats.
Scientists speculate that recent dramatic shifts in water temperature may hold the answer.
Upon retrieving the fresh Gulu River specimen, Cole recorded sea surface temperatures plummeting to roughly 13°C — the direct result of a localised cold-water upwelling event.
“The recent specimens presented with no signs of physical trauma, and the Gulu specimen was very fresh.
“For the latter, it is assumed a quick sea temperature drop may have stressed the shark, causing its death.”
Cole said sixgill sawsharks were Southern African endemics, ranging predominantly from the coastal waters of SA up into southern Mozambique.
He said they were live-bearing, top-tier bottom dwellers inhabiting the continental shelf and upper slopes at depths ranging between 70 and 140m.
Because of their affinity for deep benthic zones where upwellings occur, human encounters are rare.
Anglers and local researchers almost never cross paths with them, though commercial demersal trawlers occasionally capture them as bycatch.
Despite their specialised hunting gear, sawsharks are far from invulnerable. Females typically give birth to litters of five to seven live pups — whose saws remain soft during birth to avoid injuring the mother — yet the adults remain prized prey for larger apex predators, such as tiger sharks.
Cole said the fresh Gulu specimen had been placed in frozen storage at the museum, where he and his team would conduct a necropsy to analyse its stomach contents and piece together its final hours.
The museum is also working with the SA Institute of Aquatic Biodiversity (SAIAB) in Makhanda. SAIAB officials have been alerted to the records, and there is a strong possibility that the physical specimens will eventually be accessioned into the national fish collection for long-term genetic and anatomical research.
Cole stressed that deep-water species remained shrouded in mystery.
“We still have a lot to learn about these species, so it will be difficult to draw firm conclusions from these latest reports. Further research is urgently needed.”
