Southern California researchers part of team that discovered new fish species

A tiny, orange-vermillion colored fish has been named a new species after a team of divers from Southern California and Mexico found the wrasse in deep water among volcanoes and rugged rocks near the remote Mexican Revillagigedos Islands in the Eastern Pacific Ocean.

The Halichoeres sanchezi, or more commonly the tailspot wrasse, and its discovery in the Marine Protected Area were announced recently in a scientific journal by Benjamin Victor, an Irvine-based marine scientist who has helped name and discover more than 80 new species, 13 of those in the wrasse families.

Wrasse are a vibrantly colorful group of fish that includes 600 species; many of the tailspot’s relatives are common in home aquariums, Victor said.

Declaring a new species isn’t an easy process. It required at least six months of DNA research, and then it took another six months for Victor to write up the discovery in the journal. The announcement of a new species isn’t publicly revealed until it’s published in a science journal.

Through his research, Victor discovered that the tailspot wrasse is presently only known to be found near those islands, though that could change if El Nino worsens.

The discovery of the tailspot is unique in that most new tropical fish species are typically found preserved in jars in museums and then “described” as new, Victor said.

“To actually have the first one of a species collected live,” he said, “it’s very unusual.”

The eight specimens of the new species collected by the team range from an inch to nearly six inches in length.

The females are mostly white with reddish horizontal stripes along their top half and black patches on their dorsal fin, behind their gills, and near their tail fin.

“This species is unusual among wrasse, where the male is almost always the more colorful one,” Victor said. “In this species, the female is more colorful.”

The first photos of the unknown fish were taken in 2013 during a Reef Environmental Education Foundation expedition, and nobody on the knowledgeable team could identify the species.

“We looked at the pictures and thought no one has seen that before,” said Victor. “We didn’t know what it was.”

The mystery lingered until 2022, when a new expedition to the Revillagigedo Islands, sometimes called the Mexican Galapagos, was planned to do a survey of the ocean around the islands, which hadn’t been assessed in 20 years, Victor said.

And there was that mysterious fish to watch for.

The area is rugged with rocks and big lava fields; big Pacific rollers barrel through the clear blue water.  Most who dive there do it for research, but some visit to marvel at the vast array of sea life, especially the giant tuna and manta rays, in the waters that have been protected from fishing.

The expedition to the islands took two days on a boat from Cabo San Lucas. It was organized by professor and marine scientist Carlos Armando Sánchez Ortíz of the Universidad Autónoma de Baja California Sur. The wrasse’s official name, Halichoeres sanchezi, includes a nod to Sánchez.

The trip also included researchers from UC San Diego’s Scripps Institution of Oceanography, the Natural History Museum of Los Angeles County, the Smithsonian Tropical Research Institute, the Ocean Science Foundation and the University of Central Florida.

For two weeks, the group surveyed all four islands during 30 research dives that produced more than 5,500 photographs and 900 specimens representing more than 100 fish species. The researchers also took tissue samples for DNA analysis.

Victor said it wasn’t until the second-to-the-last day of the trip that Sanchez came up with a fish believed to be a juvenile of the mystery species.

“When he brought it up to the ship in a bag, we all said, ‘That’s it!” Victor said. “It was a different-looking wrasse, and it was a baby.”

A dive team went right back down in search for an adult, he said.

“Juveniles often look the same to related species,” he said. “The males become different because they do the mating displays, which are the first thing to change when a new species splits from an ancestral species. Males are needed to discover the difference about what’s unique for that species and that makes it a new species in science.”

On the last day of the trip, a team of divers went down 70 feet. There, they saw what they needed.

“That was the only adult; we were just so lucky,” Victor said.

Since its discovery, the fish has been documented and photographed and is now being preserved at the Colección Nacional de Peces in La Paz, Mexico. Other specimens are being stored in Scripps’ Marine Vertebrate Collection and the Natural History Museum of Los Angeles County, where they can be reviewed by researchers worldwide.

After reviewing the new species’ DNA, Victor determined the new tailspot wrasse is related to the golden wrasse, a species that lives between Baja and Ecuador.

“We found it’s 2% different in DNA sequence,” he said. “And we can interpret how many years it’s been separated. When it got to the islands, it adapted to its new conditions.”

For Victor and the other researchers, the new species discovery is akin to “the canary in the coal mine,” and they will use it to monitor the ocean warming conditions, he said. Mexican scientists will also continue to study the fish in the area of the islands and determine if its population encounters the “disastrous effects” of El Nino, he said.

“It is a small population, about 1,000, in a very vulnerable space,” Victor said, but added, “They haven’t been declared an endangered species and haven’t been put on the list because they were only officially in existence last week.”

But the damselfish, a plankton feeder also found in the area, is now extinct, he said, likely due to climate change and its impacts on the upwelling ecosystem of the eastern tropical Pacific. A sister species to the extinct damselfish has moved toward cooler waters and is now found off Catalina Island.

“It shows us the damage human-induced climate change is doing to species,” Victor said. “If El Nino carries on the way it’s going, all these fish will move here, and we’ll start seeing more and more tropical species off Southern California.”

Source: Orange County Register