—by Tim Crosby

The sturgeon, whose fierce, bony appearance betrays its prehistoric roots, is highly prized for its eggs—caviar. Ever since overseas beluga sturgeon populations crashed, prompting the United States to restrict caviar imports, demand for Mississippi River shovelnose sturgeon eggs has soared. A mature female can yield about a half-pound of eggs, which in turn would sell for almost $300, creating a strong incentive for commercial fishing operations.

For the last six years, zoologist James Garvey, who works with SIUC's Fisheries and Illinois Aquaculture Center, has studied the sturgeon living in the Middle Mississippi River—roughly from Memphis to St. Louis. Lately, what he's finding alarms him: populations of both the shovelnose sturgeon and the federally endangered pallid sturgeon are reaching a critical point.

"The harvest, during the last two or three years, has been increasing exponentially," says Garvey, whose research is funded by the U.S. Army Corps of Engineers. "We're not sure recently implemented regulations will go far enough [to protect the fish]. My fear is that...the population [is] at a stage when it might collapse, and that can happen very quickly."

That's exactly what happened in the Lower Mississippi River, and sturgeon harvesting is now off-limits from Mississippi's northern state line south to the Gulf of Mexico.

Research by Garvey and his students, who often work in conjunction with sturgeon fishing operations, has focused on such things as the fishes' typical location in the river, their feeding habits, and what water flow rates they prefer.

The research also has revealed mortality rates, which Garvey says have increased greatly among the mature, breeding-age fish that sustain the overall population. The mortality rate for shovelnose sturgeon has risen to 30-35 percent, meaning that a mature fish has a 35 percent chance of dying in any given year (including from harvesting). That rate, Garvey says, is now affecting the overall population.

"For the first time, we're starting to see the number of young, juvenile sturgeon declining," he says. "This means for every increment the mortality rate increases in the mature population, we'll see an equal effect in the juvenile population."

Worse yet, the endangered pallid sturgeon—slightly larger and paler than the shovelnose—is dying at about the same rate as the shovelnose, even though fishing is supposed to be off-limits everywhere for this species.

The two species "look a lot alike," says Garvey, "and when [pallid sturgeon] are younger it's very difficult to tell them apart from the shovelnose. Also, a mature pallid is a little larger, which means it has more eggs. There's a lot of evidence that they're being illegally harvested. Law enforcement is trying hard to stem the tide, but it's such a big system that they're having trouble."

As the sturgeon migrate from the Memphis area up to the Chain of Rocks area north of St. Louis, where they spawn, "they're continually hit by fishing," says Garvey. He believes that states bordering the Middle Mississippi need to enact tougher regulations on catch limits as a means of preserving both species. This may also be the only option to protect shovelnose sturgeon as a long-term resource for fishing operations.

"We want to make sure we utilize the resource in a wise and sustainable way," Garvey says. "The data show that what the population needs now are some really good regulations, or even a temporary closure."

If the population collapses, the effects might be disastrous.

"There's the obvious economic impact on the fishing industry," Garvey says. "But there's also the ecological [impact]. With a lot of species, we don't know what role they play in the system until they're gone."

Then too, he adds, "there's the simple aesthetic value of having the sturgeon around. This is a fish that has been around essentially since the dinosaurs."