Using DNA analysis researchers from the Florida Institute of Technology have confirmed that sixgill sharks residing in the Atlantic Ocean are an independent species from those found in the Indian and Pacific. The report was published this week in the journal Marine Biodiversity.
The new species will now be known as Atlantic sixgill shark, or Hexanchus vitulus.
Using 1,310 base pairs of two mitochondrial genes, Fit assistant professor Toby Daly-Engel, in cooperation with MarAlliance in Belize, Florida State University Coastal and Marine Laboratory, and the National Marine Fisheries Service, found enough genetic differences between what had long been considered a single species, Hexanchus nakamurai.
“We showed that the sixgills in the Atlantic are actually very different from the ones in the Indian and Pacific Oceans on a molecular level, to the point where it is obvious that they’re a different species even though they look very similar to the naked eye,” Daly-Engel said.
Deep-water sixgill sharks are among the oldest species of vertebrates on the planet, dating back over 250 million years. Reaching up to 6 feet in length, Atlantic sixgill sharks are smaller than their Indo-Pacific relatives, which can grow to 15 feet or longer.
The new distinction will enable better conservation practices based on specific population ranges.
“Because we now know there are two unique species, we have a sense of the overall variation in populations of sixgills. We understand that if we overfish one of them, they will not replenish from elsewhere in the world,” Daly-Engel said.