The silver lining to storm surge: How some baby fish ride out hurricanes to success
For good reason, humans despise the deadly impact of storm surge. However, new research shows that juvenile tarpon and snook can benefit from it. As a result, scientists are learning how to design more environmentally friendly developments that will help the fish survive.
According to ongoing research by the Florida Fish and Wildlife Conservation Commission and the Bonefish & Tarpon Trust, young tarpon and snook take advantage of storm surge and king tides, essentially riding the water into remote semi-landlocked ponds. Small tarpon and snook rule their new micro kingdoms as the water recedes, the proverbial big fish in small ponds.
According to JoEllen Wilson, a biologist with the Bonefish & Tarpon Trust, spawning season for both tarpon and snook coincides with summer high tides and storm season.
“We have extremely high water and strong winds, which are pushing (the newborn fish) back into these habitats.” They’ve been designed to reach what we call ephemerally or intermittently connected locations.”
Being swept into these shallow, often inhospitable ponds has two advantages.
For starters, the yearling tarpon and snook are protected from larger predatory fish such as sharks, jacks, and adult snook that do not have access to the area.
Second, they are perfectly adapted to survive in low-oxygen environments, giving them an advantage over both prey and competitors.
While most fish require oxygen-rich water to pass through their gills, tarpon can gulp air and absorb oxygen through their swim bladders, allowing them to survive in hot, low-oxygen conditions that would kill snapper, sea trout, or freshwater gar (some of the ponds are brackish or freshwater).
Young snook cannot gulp air, but they can survive in low-oxygen environments.
They appear to lose that ability as they mature.
“Once they reach these habitats, they’re the only large predatory fish that can survive in there,” said Matt Bunting of the Florida Fish and Wildlife Conservation Commission, whose research tracked the yearling fish in and out of these isolated ponds on Florida’s west coast. He claims that the same behavior occurs on the east coast as well.
Bunting, who grew up in Cooper City fishing for small tarpon in suburban canals and ponds, has seen juvenile tarpon survive in water temperatures above 100 degrees Fahrenheit with dissolved oxygen levels at zero, “to the point where there’s been a mass fish die-off in one of these ponds, and tarpon are the sole fish that are surviving,” he said.
As a result, yearling snook and tarpon can feast on little mosquito fish in these semi-landlocked ponds and have the entire food supply to themselves.
According to Bunting’s research, tarpon and snook will stay in the ponds for one to three years, but the closer they are to the estuary, the sooner they will leave. A king tide will occasionally bring enough water.
His research found that some fish died after three years, which was the time it took for a second tropical storm or hurricane surge to reach them.
Bunting and his team collected data by outfitting yearling tarpon and snook with acoustic transmitters that would ping when the fish approached any of the receivers installed in the pond and downstream creek system.
Water-level sensors were also installed in the ponds by the researchers. The study found that when water levels rose, the fish left.
Bunting and his team tagged fish when they were about 12 inches long and less than a year old in the spring. He stated that they usually leave the ponds during summer and fall flooding events.
Nobody knows how small the fish are when they are first swept into the ponds.
Tarpon, on the other hand, spawn offshore in the spring and summer, while snook spawn in inlets in the summer.
Their fry are swept up and down coastal areas, as well as into estuaries, in search of both shelter and food. Their ability to hide in semi-landlocked ponds is an evolutionary adaptation that gives them an advantage in a world where fish eat fish.
It can also be used by conservationists to highlight environmentally friendly waterfront design.
Wilson’s research focuses on how to redesign canal systems to benefit juvenile tarpon and snook survival. One study used an existing canal area to create a variety of shallow estuary environments. Some had open creek mouths, while others, like the ponds in Bunting’s study, were semi-landlocked and shallow.
She discovered that baby tarpon and snook grow faster in man-made estuaries than in straight, deep canals. She also discovered that a shallow estuary creek with an open mouth for travel but a semi-landlocked shallow area in the back end for shelter was the most productive environment for tarpon and snook.
Climate change, and the resulting sea-level rise in Florida, are factors.
King tides are now able to reach further inland. Larger storm surges caused by more powerful hurricanes can have the same effect. It appears that juvenile tarpon and snook have adapted to it.
They are not, however, adapted to habitat loss. Florida is the fastest-growing state in the union, with a population of 22 million people, more than doubling that of the 1980s. Much of that growth is concentrated along the coast, where subdivisions are devouring estuaries and wetlands.
“Stormwater ponds can benefit fish,” she says, “but they need to be designed to allow for the occasional inflow and outflow of small fish.”
Wilson hopes to find a way for ecosystems and human development to coexist by examining both Bunting’s natural pond study and her research.
“Development will occur, particularly in this region,” she predicted. “The question is, can we develop in a way that also allows for highly functioning nursery habitats (for tarpon and snook)?”
