They’re called “fish storms” because they curve out to sea and seemingly do little more than hassle a bunch of tuna, marlins and swordfish.
But as they churn over open water, tropical storms and hurricanes actually provide a strong boost to marine life by uprooting nutrients from the ocean floor and driving them to the surface, experts say.
That provides a banquet for everything from shrimp to sharks, as plankton dine on the nutrients, small fish gorge on the plankton and bigger fish feast on the little fish.
“The agitation from storm events brings up nutrients locked up in the sediment,” said Jerald Ault, a marine biology professor at the University of Miami. “Then it moves through the food chain.”
So far this year, there have been three such fish storms – so called by meteorologists and weather buffs – in Chantal, Dorian and Erin, and in the past five years, 38.
Although a single storm isn’t enough to change these patterns, several tropical systems following the same general path have drawn marine creatures to specific areas, such as offshore regions of Florida, Africa and the Caribbean, Ault said.
Fish in those areas tend to spawn in the nutrient and oxygen rich waters, and the survival rates of their young tend to be better, said Ault, who conducts surveys of fish populations around Florida.
When fish congregate in storm-traveled waters, birds and commercial fishermen soon follow.
“Fishermen know where the fish are most productive, and in today’s world, they use satellite technology to find them,” said Ault, who teaches at UM’s Rosenstiel School of Marine and Atmospheric Science.
While hurricanes help nourish fish, fish help feed information to hurricane forecasters, Ault said.
Because they like to swim in waters just warm enough for tropical storms to develop, tarpon have been tagged with satellite-linked devices, which measure sea temperatures. The data are transmitted to computer models used by the National Hurricane Center.
“The tarpon are helping scientists to get ocean data, specifically heat content, which in turn helps forecast data,” he said.
While they may be better fed after a storm passes, what do fish do when tropical storms and hurricanes are about to hit their area?
No one knows for sure, because there have been no specific studies on the subject. But Ault suspects fish are fully aware when storms approach because “they are very attuned to barometric pressure and temperature changes. The fish literally feel the changes,” he said.
Bigger fish probably swim out of the way or dive as deep as they can to ride out the storm. Small, weak or less mobile fish are vulnerable to being killed.
“Certainly, they hunker down,” Ault said.
Aside from helping fish, tropical systems, whether they hit land or not, also help keep equilibrium in the atmosphere. They distribute heat around the globe and prevent the seas from getting too hot, experts say.
With their powerful circulations acting like an oil drilling rig, hurricanes dredge up cold water from the depths and at the same time release ocean heat into the atmosphere.