Biologists search spillway for ‘relic of dinosaur age’

Courtesy Photo

Dr. Jack Killgore, with the U.S. Army Corps of Engineers, holds a shovelnose sturgeon. The Louisiana Department of Wildlife and Fisheries and the Corps have joined together to save sturgeon that floated into the spillway.

Biologists with the Louisiana Department of Wildlife and Fisheries and the U.S. Army Corps of Engineers have spent the last two weeks scouring the receding water of the Bonnet Carre Spillway for an endangered species of fish that is considered to be a relic of the dinosaur era.

The pallid sturgeon is a ray-finned fish located in the rivers of the Mississippi River valley. Named for its pale coloration, the pallid sturgeon is closely related to the common shovelnose sturgeon but is much larger, averaging between 2 ½-5 feet in length and 85 pounds in weight at maturity.

The pallid sturgeon takes 15 years to mature and spawns infrequently, but can live for up to a century.

“With the spillway opening, both pallid and shovelnose sturgeon, which are indigenous to the river, become stranded in the spillway,” biologist Tim Ruth said.

Pallid and shovelnose sturgeon are very similar in appearance and both have been protected since 1991.

“We have to protect the shovelnose sturgeon as well as the pallid sturgeon because most people wouldn’t know the difference between the two,” Ruth said. “There is still a lot of confusion between the two species because they have a lot of similar intermediate characteristics.”

So far biologists have found two pallid sturgeon. Ruth said he expects to find more.

“In 2008 when the spillway was last opened, we collected 50 sturgeon, 14 of which were endangered pallid,” he said.

Biologists are rushing to find as many pallid sturgeon as possible so that they can return the stranded fish to the river.

When a pallid sturgeon is discovered, they are tagged so that their movements can be studied after they are returned to the Mississippi.

“We also collect fin tissue so that we can  get an estimate of age and growth,” Ruth said. “It also help us to determine population abundance and will give us information to pinpoint small differences between the pallid and shovelnose sturgeon.”

All detailed measurements that the biologists take are loaded into a database to help researchers better understand the ancient fish.

Though pallid sturgeon are endangered, they are actually older than the dinosaurs, Ruth said, and have remained essentially unchanged for more than 200 million years.