Hurricane Harvey Didn’t Stop These Fish From Mating

Every summer, a symphony of grunts, croaks and roars echoes below the surface of the western Atlantic and the Gulf of Mexico to signal the launch of spotted seatrout spawning season.

Last year, the noisy process—which finds males vibrating their air bladders in hopes of attracting fertile females eager to mate—coincided with the onslaught of Hurricane Harvey, a category 4 storm that made landfall in Texas on August 25. And as JoAnna Klein reports for The New York Times, a series of recordings captured by microphones placed at popular spawning grounds across Aransas Bay reveals just how persistent the trout are in their pursuit of reproductive success: Not only did they spawn on the days preceding and following the storm, but also on the day the eye of the hurricane passed directly over their habitat.

“These fish are resilient and productive, even in the face of such a huge storm,” lead author Christopher Biggs, a marine ecologist from the University of Texas at Austin, says in a statement. “On land, it was complete destruction, but these fish didn’t seem disturbed.”

The researchers’ findings, published in Biology Letters earlier this month, emerged largely by chance. Biggs tells Eos’ Jenessa Duncombe that he and his colleagues initially set out to study the fish’s breeding patterns, including where and how they spawn. Trout reproduction is best observed via aural methods, as the waters these fish call home tend to be too murky for visual analysis, so the researchers set up 15 underwater recording stations between April and June 2017.

When news of Harvey’s projected path of destruction broke, Biggs was attending a conference in Florida. He raced home and managed to retrieve just under half of the monitoring devices, but was forced to evacuate before he could recover the rest. Thankfully, two of these stranded stations survived the storm, providing the scientists with an unprecedented glimpse of fish spawning in the midst of a major disaster.

At first, Biggs and his team thought Harvey’s 145 mile-per-hour winds and 10-foot storm surge had prevented the recorders from capturing the trout’s distinct calls. But they soon heard hints of the males’ mating cries, which Klein of The New York Times says sound alternatively like “a panther standing behind a trickling stream of water” and a “chorus of chain saws.” (The Louisiana State University AgCenter further notes that individual males produce croaking sounds, while hordes of males release drumming or roaring sounds.)

According to Eos’ Duncombe, the trout continued spawning during Harvey’s immediate aftermath, but on the first five days following the storm, they began their mating ritual around two and a half hours earlier than usual.

One possible explanation for this shift is colder water temperatures introduced to the fish’s native bay habitats by the storm’s fresh water. As Duncombe writes, this change mirrors the species’ springtime spawning patterns, which find them spawning earlier in the day in response to cooler water temperatures.

By the end of the five-day period, the water had returned to its normal temperature, and the trout had resumed their typical spawning habits. In lieu of the widespread havoc wrought by Hurricane Harvey, the spotted seatrout’s resilience—and dogged dedication to reproduction—represented a relatively uplifting discovery.

“This data gives us a little insight into how key species will handle changing and unpredictable conditions,” Biggs concludes in the statement. “They are somewhat preadapted to this. They regularly deal with changing situations. They might be better suited to handle the changing climate in the future.”

Meilan Solly | | READ MORE

Meilan Solly is Smithsonian magazine's associate digital editor, history.