Toward the end of 1988, the Russian research vessel RV Vityaz visited a remote underwater seamount off the island of Madagascar. The researchers on board collected several specimens of sharks, skates and rays in a bid to understand the region’s marine life better. More than three decades later, scientists have confirmed that six of those skates, each brown and flat with a distinct long, stiff snout, belong to a species previously unknown to science.
In a recently published study, the researchers have now described the fish, aptly naming it the brown longnose skate (Leucoraja longirostris).
A German fish and fisheries researcher, Matthias Stehmann, who was aboard the RV Vityaz, immediately recognized at the time that the specimens represented a new species, Simon Weigmann, associated scientist at the Leibniz Institute for the Analysis of Biodiversity Change in Germany, told Mongabay in an email. However, the actual confirmation took a while.
“He brought these specimens to my attention and we — together with two further colleagues — examined all available specimens as well as a large number of comparative specimens and finally published the description of the new species,” Weigmann said.
Since the 1980s, no new specimens of the brown longnose skate have turned up, Weigmann added. This suggests the species may be limited to the region where it was collected: a group of submerged seamounts called Walters Shoals, located on the southern end of the Madagascar Ridge, about 760 kilometers (440 miles) from Madagascar and 1,100 km (680 mi) from South Africa. Weigmann and his colleagues had previously described a new species of catshark from the deep waters of the Madagascar Ridge. They named it Bach’s catshark (Bythaelurus bachi) after German composer Johann Sebastian Bach.
Skates are closely related to sharks and rays, belonging to the class Chondrichthyes. However, skates, which have flat bodies, resemble rays more closely. Many species of sharks, rays and skates are today threatened from overfishing, habitat destruction and marine pollution.
The newly described brown longnose skate could also be in trouble. The species may have a “very restricted distribution,” Weigmann told Mongabay, which may put it in contact with longline and deep-water trawl fisheries.
Not much is known about the fisheries operating in the region of the Madagascar Ridge, however, he added. But it’s likely that, like many other species of skates, this deepwater skate also is long-lived, reaching sexual maturity late and reproducing few offspring, which, Weigmann said, would indicate that the species may be “unable to withstand intensive fishing pressure.”
“Walters Shoals was previously heavily fished, and this pressure may recur in the future,” he added.
Banner image of newly described species of skate (Leucoraja longirostris). Courtesy of Simon Weigmann.
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