Fisheries researchers at Tennessee Tech University found one piece of a scientific puzzle that just may help save an endangered species from extinction.

The pallid sturgeon is known as the "dinosaur" of the Missouri and Mississippi rivers and has been on the endangered species list since 1990. This primitive species has been around since the late Cretaceous period 70 million years ago when dinosaurs roamed the earth. Today, there are believed to be fewer than 10,000 left in the Missouri and Mississippi rivers.

The U.S. Fish and Wildlife Service is expected to make a determination in September whether to invoke the "Similarity of Appearance" provision under the Endangered Species Act to protect the pallid sturgeon from incidental catch by commercial fishermen. Doing so will end commercial fishing for the more abundant shovelnose sturgeon in the Tennessee waters of the Mississippi River.

The shovelnose sturgeon fishery is a valuable one in Tennessee. Female shovelnose sturgeon are harvested for their eggs, which are processed for caviar. A pound of the pre-processed eggs wholesales for about $100, and an average mature female shovelnose sturgeon can produce about half a pound of eggs.

Scientists believe the endangered pallid sturgeon is no longer reproducing in its natural habitat in sustainable numbers because the rivers have been so altered by dams and channelization. TTU scientists have now proven that commercial fishing is having a direct and detrimental impact on the species as well.

"Biologists elsewhere were concerned because endangered pallid sturgeon was showing up in fish markets occasionally. Those same biologists began noticing that wherever you allow fishing for the common shovelnose sturgeon, you don't see large, old pallid sturgeon," said Phil Bettoli, a TTU biology professor and assistant unit leader for the U.S. Geological Survey's Cooperative Fishery Research Unit based at Tech.

State wildlife officials asked Bettoli's team to research the problem of incidental catch of pallid sturgeon. To do so, he and his graduate student accompanied commercial fishermen in Tennessee during the 2007 fishing season and documented several occasions where the endangered fish was being harvested in gill nets alongside the more plentiful shovelnose sturgeon. The incidental catch rate in the Mississippi River was about 2 percent, Bettoli said. The endangered species also was being captured and killed in "ghost nets" lost or left behind in the river.

"It turns out that unless it's a big pallid sturgeon with its distinctive pale coloration, they're really hard to tell apart from the shovelnose sturgeon," he said. "We often had to take a tissue sample and send it to a genetics lab in order to positively identify them after the fact."

The U.S. Fish and Wildlife Service published its initial proposed rule announcement in the Federal Register Sept. 22, 2009, and the public comment period closed in February 2010. A determination whether to close the fishery is expected in late August or early September and should be published in the register by Sept. 22, 2010.