Strong earthquakes like those felt in Northern California last week are a stark reminder for people to plan — perhaps fortifying their home or business, or at least finally building the earthquake equipment.

But for the Devils Hole pupfish, an endangered species found only in a deep limestone cave in Death Valley, an earthquake signals it’s time to do something more intimate.

Scientists believe the fish’s likely response to the magnitude 7.0 earthquake that struck a large swath from San Francisco to Reno to southern Oregon was to increase spawning activity to protect their population. It is a phenomenon that has occurred in several previous earthquakes.

About two minutes after the earthquake, water began flowing in Devils Hole – about 500 miles from the quake’s epicenter. Scientists estimate that the waves, known as seiche, were nearly two feet high. For the typical still-water environment, the waves disrupted the shallow shelf that the juveniles use as a spawning area, likely throwing their eggs deep into the cave.

“There have been observations in the past that fish evolved to spawn more after floods and earthquakes,” said Kevin Wilson, a biologist with the National Park Service. “Think of it this way: ‘Oh no, my home, my living space has changed drastically. I better try to have more babies.’”

According to scientists, the reaction is not irrational.

In 1967, pupfish were one of the first to be listed as an endangered species in the United States. Before the mid-1990s, scientists counted between 200 and 250 Devils Hole pups each spring. But over about 20 years, the population of fish fell to an average of about 90, with an all-time low of 35 fish in 2013.

However, population numbers occurring in spring and fall have been higher recently. Scientists found 191 juvenile fish in April – the highest spring number since 1999. In September, 212 fish swam around Devils Hole.

In the short term, Wilson said, earthquakes are not good for the fry. The waves push the algae that grow on the limestone shelf and small invertebrates that the fish eat deeper into the cave – most likely too deep for the small swimmers to access. But in the long run, there is a benefit, he said. The waves remove rotting organic material that can lead to oxygen-depleted pockets, which can be fatal to the fry’s eggs.

Wilson, who has studied pupfish for years, said scientists can learn a lot from Devils Hole and these tiny fish about the impact of issues like climate change.

“I like to call Devils Hole a bit of a canary in the coal mine or a lodestar,” Wilson said. “The changes we are seeing now in response to climate change and increased air temperature, and how they are affecting this ecosystem, we can apply to other ecosystems that become warmer in the future.”

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