Extinct in the Wild, Fish Return to Habitat in Mexico

Golden skiffia are swimming again in Mexico.

About a quarter-century since the small brilliant fish disappeared from its only natural habitat, golden skiffia (Skiffia francesae) were released back into the wild. The timing coincided with traditional Día de Muertos (Day of the Dead) celebrations.

“The Day of the Dead is a traditional Mexican celebration, when it is believed that people’s deceased ancestors return to the land of the living for one night, to talk and spend time with their families,” said Omar Domínguez-Domínguez, a professor and researcher from the Michoacan University of Mexico, who led the reintroduction. 

“Releasing the golden skiffia around this time is a metaphor for how the species has come back from the dead to return to its home, not for one night, but forever.”

Researchers aren’t sure why golden skiffia disappeared in the wild because the fish weren’t studied before they went extinct. They were last spotted in the 1990s. They suspect that pollution and the introduction of other species likely led to their disappearance, Dominguez-Dominguez tells Treehugger.

They play an important role in the ecosystem because they regulate algae and eat the larvae of mosquitoes that transmit disease.

Because the fish are so small, they have little value for some fisheries that collect goodeids, this family of fish. Many of them are known as splitfins. Species losses like these can affect some threatened freshwater fish around the world, says Harmony Patricio, SHOAL conservation program manager and Re:wild’s freshwater fish conservation program manager.

SHOAL is a global partnership working for freshwater fish conservation. Re:wild’s mission is to protect and restore the biodiversity of life on Earth.

“Knowledge gained through research and action to conserve goodeids is relevant for effectively conserving a broad array of fishes,” Patricio tells Treehugger.

“They also act as indicators of the health of a freshwater system—when fish populations are healthy, the ecosystem is too. When populations are declining, it is a sign of a failing system. Freshwater fishes and ecosystems are a critical part of human livelihoods and wellbeing around the world.”

Long-Planned Project

Scientists released about 1,200 golden skiffia into their native habitat in the upper part of the Teuchitlán River in Jalisco, Mexico. The fish came from a conservation breeding program.

“The fish were marked and we will sample every two months to follow the population,” Dominguez-Dominguez says. “We expect that in the coming months we will start to find fish that are unmarked, which will be a sign that the species is surviving and reproducing in the wild.” 

In order to prepare for the release, the fish were first placed in ponds so they could learn to adapt to semi-captive situations. They were dewormed and marked for identification and then put in floating cages in the river for at least a month so they could adapt to natural conditions.

Plans for the release first started in 2014, when scientists from Michoacan University of Mexico and fishkeepers from the Goodeid Working Group began removing the threats that triggered the species to become extinct in the wild. They helped restore the golden skiffia’s habitat and began removing non-native species from the ecosystem.

“The team that released the golden skiffia has been preparing for this for years and have learned so much along the way,” Patricio says.

“They will conduct periodic population monitoring surveys and hope reproduction rates will reach levels needed for the population to become self-sustaining. We hope that this reintroduction can help serve as a model and conservation success story for similar efforts around the world.”