Giant Jumping Sturgeon Stir Up Mystery in Florida River
for National Geographic News
|August 17, 2006|
Florida vacationers may be aware of the potential dangers of sharks and alligatorsbut what about Gulf sturgeon?
The giant fish trace their roots back to the days of dinosaurs and can grow up to 8 feet (2.5 meters) long and weigh up to 200 pounds (91 kilograms).
They can also jump six feet (two meters) out of the water and crash into unsuspecting boaters.
This year, there have been at least five such collisions on the Suwannee River in northwestern Florida, some of them resulting in serious injuries.
About a week ago, 23-year-old Blake Nicholas Fessenden was injured after a four-foot-long (one-and-a-quarter-meter-long) sturgeon jumped out of the river and knocked him off his personal watercraft.
His girlfriend, who was riding another watercraft behind Fessenden, was able to get to her unconscious boyfriend and hold his head above water before passengers on another vessel arrived to pull him from the river.
The same day, another couple was driving a boat on the river when a sturgeon jumped up and smashed into the boat's windshield.
Wildlife officials are quick to point out that the collisions are purely accidental.
"These are random collisions there is no parallel to an attack," said Jerry Krummrich, a freshwater fishery biologist with the Florida Wildlife Commission in Lake City.
The experts say the collisions are probably the result of an increase in boatersand possibly a larger sturgeon populationon the Suwannee River.
"There's a lot of boat traffic on the Suwannee in the summer, which is when you'll find the sturgeon in the river," said Alan Huff, a research administrator with the Fish and Wildlife Research Institute in St. Petersburg, Florida.
"More boats and more fish lead to more collisions."
As suggested by their appearance, with rows of armored plates running along their backs and sides, sturgeon date back more than 200 million years to the era of dinosaurs.
But their behavior remains poorly understood by scientists.
A subspecies of the Atlantic sturgeon, Gulf sturgeon are found in the coastal rivers of the Gulf of Mexico.
The 207-mile-long (333-kilometer-long) Suwannee River, which runs through Georgia and Florida, contains the largest population of Gulf sturgeon.
(See an interactive map of the Suwannee River.)
According to one estimate, there were between 5,500 and 7,650 adult sturgeon in the Suwannee in 2001.
The sturgeon spend the summer in the river. They spawn but do not feed there, instead moving out into the Gulf for food in the winter months.
Why they jump, however, remains a mystery.
"No one [seems to have found] anything that plausibly explains this phenomenon," said Huff, who began studying the sturgeon in the Suwannee River some 30 years ago.
The fish, scientists speculate, could be jumping to avoid predators or to flush out their gills. They may do it to gulp air, or perhaps just for joy.
"We do know that they're not doing anything to intentionally harm boaters," Huff said.
"They're one of the more mellow, placid fish out there. They just like to jump."
Largely unspoiled, the Suwannee River originates in the Okefenokee Swamp in Georgia and runs southwest into Florida, dropping in elevation through limestone layers resulting in Florida's only whitewater rapids.
In the summer the river can get crowded with recreational boaters.
"The mid-river seems to be the most populated," said Karen Parker, a spokesperson for the Florida Wildlife Commission in Lake City.
"On a weekend there might be hundreds of boats out there, with people going tubing or kayaking."
Parker says there are more than a million registered boats in Florida.
"It's inevitable that we will have these [sturgeon] collisions when more boaters come in contact with the animals," she said.
"That's showing itself all over the state with all kinds of critters."
"With the development and encroachment on habitat, we're going to have more and more encounters between people and animals," she added.
Gulf sturgeon were listed as threatened under the U.S. Endangered Species Act in 1991 after a century of being fished for meat and caviar. It is now illegal to catch and kill sturgeon.
There are signs that the population has been increasing since then.
"People are seeing the sturgeon jumping out of the water 24/7 in the summer months," Huff, the St. Petersburg researcher, said.
"[One of our biologists] said that with so many people on personal watercraft on the river, it's like [people] are playing Russian roulette [with these fish]."
Huff says his office is planning to put up signs at river access points warning people about sturgeon collisions.
Despite their possible increase in numbers, sturgeon are still vulnerable to overharvesting and habitat degradation, the experts say.
"I sincerely hope that not an ounce of mentality anywhere is pointed toward getting rid of or reducing these fish [because of these collisions]," Krummrich, the biologist, said.
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