Scientists discover new species of fish off Baja California coast
SAN DIEGO (FOX 5/KUSI) — Researchers have discovered a new species of tropical fish during an expedition to remote islands off the Pacific coast of Mexico.
Named the Halichoeres sanchezi, or the tailspot wrasse, the colorful species were found living among volcanic rubble in the waters surrounding the Revillagigedo Archipelago — an island system known as the “Mexican Galapagos” for its vast marine biodiversity.
The discovery was officially penned into the scientific record on Tuesday with the publication of a paper on the species in the journal, PeerJ. Halichoeres sanchezi.
“It’s amazing that we can still find species that are new to science in a place where people are visiting pretty regularly — it just shows how big and complex the world is,” said UC San Diego’s Scripps Institution of Oceanography’s Ben Frable, who was one of the scientists in the expedition.
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Based on the specimens examined by Frable and the rest of the team, the species ranges in size from about an inch long to nearly six inches, Scripps said. They are also believed to be hermaphroditic, beginning life as female with some later transitioning to male.
The smaller female fish are mostly white with reddish horizontal stripes along their top half and black patches on their dorsal fin, behind their gills and just in front of their tail fin. The male fish were described by Frable as having an “orangy red up top fading to a yellow belly with a dark band at the base of the tail.”
According to Scripps, researchers believe they are related to other fish in the wrasse family, such as the California sheephead and the bluestreak cleaner wrasse. However, the species are believed to be endemic, meaning it is unique to the area and cannot be found anywhere else on earth.
Located just 250 miles south of the Baja California peninsula, the Revillagigedo islands are well-known for its abundance of marine life, due in part to protections that prevent fishing in the area.
This preservation of the island’s aquatic biosphere regularly attracts recreational scuba divers and scientists, offering them a “window back in time to before intensive fishing,” as Frable described.
Compared to other islands, however, the undersea wildlife of the Revillagigedo remain much less studied. According to Scripps, the last roboust scientific survey of the island’s fish species occurred more than two decades ago.
That lapse is what prompted marine scientist Carlos Armando Sánchez Ortíz of the Universidad Autónoma de Baja California Sur to mount the latest expedition alongside a team of international researchers in November 2022, leading to the discovery of the tailspot wrasse.
Over the course of the two week excursion, the group, which included dozens of researchers and underwater photographers, explored all four islands in the Revillagigedo system in 30 different research dives, collecting over 900 specimen representing more than 100 species of fish.
As Frable recalled, the team encountered the tailspot wrasse on the final day of the trip when Sánchez had collected a small red fish in the waters off San Benedicto Island about 70 feet below the surface without really knowing what it was.
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Back on the boat, Frable said they realized the specimen was some type of wrasse and matched a photograph of a fish of an unknown species captured by a diver back in 2013.
During one of the final dives of the expedition, Frable spotted another one of this species of fish, but it slipped through the team’s nets. However, on the trip’s last dive, Frable and National History Museum of Los Angeles County’s William Lundt were able to collect another specimen.
According to Scripps, DNA analysis confirmed the conclusion that the fish were a part of a district species, bringing the total number of endemic fish species for the Revillagigedo Archipelago up to 14.
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