The earthquake in Northern California has an endangered species of fish in Death Valley busy

Strong earthquakes like the one felt last week in Northern California are stark reminders for people to plan — perhaps to fortify their home or business, or at least finally build that earthquake kit.

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

Scientists say the fish’s likely response to the 7.0 earthquake, which rattled 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 happened during several previous earthquakes.

About two minutes after the quake, water in Devils Hole — about 500 miles away from the quake’s epicenter — began to flow. Scientists estimate that the waves, known as a seiche, were nearly 2 feet high. For the typical stillwater environment, the waves disturbed the shallow shelf that the pupfish uses as a spawning area, likely knocking eggs deep into the cave.

“There have been observations in the past that after floods and after these earthquakes, the fish have evolved to respond by increasing their spawning,” said Kevin Wilson, a National Park Service biologist. “Think of it as, ‘Oh, no, there’s been a drastic change to my home, my habitat. I’d better try to have more babies’.”

The answer is not irrational, according to scientists.

In 1967, the pupfish was labeled an endangered species, one of the first in the United States. Before the mid-1990s, scientists counted between 200 and 250 Devils Hole pupfish each spring. But over the course of about 20 years, the fish’s numbers declined to an average of about 90, with a record low of 35 fish in 2013.

But population numbers, which occur in the spring and fall, have been higher recently. Researchers found 191 pupfish 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 pupfish. 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 little swimmers to access. But in the long term there is an advantage, he said. The waves clean out decaying organic matter that can cause pockets of low oxygen, which can be fatal to hatchling eggs.

Wilson, who has spent years studying pupfish, said researchers can learn a lot about the effects of issues like climate change from Devils Hole and the tiny fish.

“I like to call Devils Hole kind of a canary in the coal mine or a bellwether,” Wilson said. “The changes we’re discovering in response to climate change and increased atmospheric temperature right now, and how that’s affecting this ecosystem, we can apply to other ecosystems that will be warmer in the future.”

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