Destin Log 10/23/01

Sturgeon tags help knowledge soar

By John Ledbetter, staff writer

The information age and the age of dinosaurs are being linked by satellite.

Biologists are using computer-chipped tags on the Gulf sturgeon, a fish virtually unchanged for 200 million years, to assist in gathering data to help the threatened species recover.  

The tags record the wanderings of the andromous fish as they migrate from the salt water of the Gulf and bays to the fresh waters of coastal rivers where they spawn.

  The wires securing the tags degrade after about six months in the brine, and the tags float to the top and download the history of the fish’s locations to a satellite, which relays the info to biologists studying the primitive-looking fish.

“We save the ‘pop-up tags’ (satellite tags) for the fish that weigh over 100 pounds,” said U.S. Fish and Wildlife biologist Laura Jenkins, while she piloted an agency boat last week near the mouth of the Choctawhatchee River. “We know fish of that size will go into the Gulf, while the smaller ones may stay in the bay.”

Jenkins and other members of the sturgeon task force team have deployed gill nets in the Choctawhatchee River to catch the species that can weigh up to 300 pounds and reach lengths of nine feet. They check the nets every two hours, with a typical haul being two or three sturgeon.

  Since they started tagging a couple of weeks ago, they’ve caught more than 100 sturgeon, with a handful going over 100 pounds but only three getting the prized pop-up tags. The rest get more conventional “sonic tags”  that allow biologists to track the sturgeon with the use of a directional hydrophone. 

Once located, biologists record information concerning the water’s salinity, dissolved oxygen, turbidity, depth, temperature and the substrata or type of bottom where the fish is found. The information will ultimately be used to formulate a management plan to restore the fish to healthy levels, when a limited recreational and commercial use can start again.

Captured fish are weighed and measured and biologists also take tissue samples, for forensic use. Some caviar isn’t what it’s marketed as, and the genetic information from these tissue samples can help bust people who try and sell roe obtained from protected Gulf sturgeon.

Caviar is one of the reasons the fish is on the threatened list. In the early part of the 20th century, after the Russian Revolution dried up conventional caviar supplies, a commercial fishery for the Gulf sturgeon thrived in Florida’s Panhandle. But overharvesting a species that can’t reproduce until it’s 9-12 years old quickly wiped out the industry.

The age of the Gulf sturgeon being captured in Walton County also intrigues the biologists. They take a cutting from the thickest spine of the pectoral fin (which regenerates) to determine the age.  Experts think the Gulf sturgeon lives up to 50 years, not quite as long as some species of sturgeon, which can approach 100. “Each year the fin gets another ring,” said biologist Tom Sinclair. “Just like a tree.”

The sturgeon is easy to identify, with big whiskers near its mouth and sharp scutes — hard cartilage plates — running down its back. Sinclair in particular is enjoying wrestling the fish out of the nets and into the holding tank of the work boat. Normally a supervisor in Atlanta, he wrestles “paper fish” instead of the real thing.

“These are such neat creatures,” Sinclair said.  “They’ve got this big mouth and it’s always moving. They are strong and thrash about in the nets, but once you pick them up, they get really docile, like a big baby.”

Jenkins is fascinated by the fact the sturgeon has lived so long without changing. “They’ve adapted to all the different pressures, all the habitat changes,” she said. “And they still hold on. They’re survivors.”

Even in the age of satellites.

John Ledbetter is a staff writer for The Log and can be reached at 654-8443 or at John_Ledbetter@link.freedom.com