Sturgeon surgeons

[Note: this story has been modified since its original posting.]

It’s not easy being a pallid or shovelnose sturgeon these days.

In one day last week a group of 20 near Boonville were caught in nets, cut open and implanted with transmitters and tags, had a sample of their eggs removed, and had a portion of their fin clipped for genetic coding. Then the fish were stitched up and sent back on their journey up river to spawn.

It’s all part of an effort to understand the two species of sturgeon in the Missouri River and help increase their populations. But try telling that to a sturgeon as it lies belly-up under a scalpel.

Then again, these sturgeon don’t have an easy life. In one season some travel as many as 200 miles upriver before they spawn and up to 600 miles downriver afterwards.

Life has become even more difficult for sturgeon because the Missouri River has changed so dramatically since these fish first swam in the river.

“The river most of us are used to looks nothing like it once did,” said Aaron Delonay, an ecologist for the U.S. Geological Survey research center on New Haven Road. “It had braided channels, islands, sandbars, water moving in all different directions, habitats in shallow and deep water, fast and slow currents, straight and narrow channels.”

Many river creatures, especially the sturgeon, benefit from the kind of diversity that no longer exists on the river, said Delonay, who has studied sturgeon for nearly 10 years. For the past three years, he has led a crew of researchers using complex technology to learn as much as they can about the spawning habits of sturgeon.

“This is one portion of the comprehensive USGS sturgeon research designed around trying to understand the history, life cycle, impacts of river management and habitat aimed at restoring them before they disappear,” he said.

Mandated by the federal Endangered Species Act to do something to help the pallid sturgeon, the Corps of Engineers has appropriated $54 million this year for its fish and wildlife recovery effort. About two-thirds will go to the pallid sturgeon research and habitat restoration, said Mike George, project manager of the Missouri River Recovery Project Manager for the Corps. Of that, about $5.4 million will partially fund the USGS’s sturgeon research.

When the U.S. Fish and Wildlife Service issued its biological opinion to the Corps in 2000, George said, the dire status of the pallid sturgeon put their recovery on the front burner. In 2003, Fish and Wildlife amended its biological opinion, which allowed for habitat restoration to complement ongoing research.

“It said although we didn’t know everything we needed to know, we do know enough to start creating some shallow water habitats and just mechanically create the diversity that the flows created before the river was dammed,” George said.

The USGS research is even more important this year. In May, the U.S. Army Corps of Engineers plans to release water from upriver reservoirs to create a two-day “spring rise.” A rise planned for March was canceled because there wasn’t enough water in the reservoir system.

The Corps of Engineers hopes the spring rise will increase the spawning of pallid sturgeon by mimicking the natural pulses of spring snow melts that occurred before the river was dammed. But some farmers and politicians are not convinced the pulse is worth the risk of potential flooding.

Delonay said the USGS doesn’t take a position on the spring rise. “We stand ready to evaluate the results,” he said. “But we do know that when we don’t know much about the fish, a good template is to begin to look at what used to occur.”

A typical day

This time of year is busy for Delonay and his crews. Because they’re racing against increasing temperatures, they often get out on the river as early as 5 a.m. and don’t finish filing the sturgeon’s blood samples at the lab until 10 at night. Higher temperatures put stress on the fish, which isn’t ideal when they need to recover from surgery and prepare to spawn.

The crew recently spent three days in mid-Missouri with full days on the river near Jefferson City, Mokane and Boonville. Nebraska and Iowa are the next stops.

The day starts with the crews in two boats pulling nets out of the river that have a mesh specifically designed to catch shovelnose and pallid sturgeon. Crews place the nets in areas sturgeon prefer to minimize the capture of other species.

They’re looking for sexually mature females of a certain size who look ready to spawn. While it’s the pallid that researchers want to learn most about because of their federally endangered status, pallids are so rare that the crews seldom come across any. They did net one pallid, a male, during the Boonville river outing and immediately released it.

Although there are differences in the two species, learning the habits of the shovelnose can be applied to the pallid. Pallids live an average of 60 years compared to an average age of 20 for the shovelnose. Pallid females spawn every two to five years instead of every other year. They’re more translucent, and without the shovelnose’s scale-like scutes on the belly.

By around 11 a.m. , one crew is back on the river bank near the parking lot of the Franklin Island Conservation Area with nine females and Delonay is ready to start surgery.

“The easy part is catching the fish,” Delonay said. “The hard part starts now.”

Delonay wields the scalpel while another crew member keeps a record of which transmitter and tag goes into each fish along with samples of blood and eggs from each fish.

Delonay takes a blood sample, removes the needle and rubs the spot with his thumb, then makes an incision on the fish’s lower left underside. The incision bleeds a little, and that’s good.

“It’s better if it’s a little bloody,” Delonay said. “If we cut in a spot that doesn’t bleed, it won’t heal well.”

Next Delonay removes a sample of eggs and implants an “archival tag,” a cylindrical device that includes a tiny computer chip that will record the sturgeon’s location and vital statistics every 15 minutes. When the crews recollect the fish in July, they will retrieve the tag and file the information. Next is the transmitter. The device is about 2 inches long and sends information through a dual system. A radio frequency transmits in shallow waters, while an ultrasonic frequency transmits in deep water.

Delonay uses a needle with a hollow plastic sleeve to poke a hole in the fish’s belly closer to its tail. He inserts the transmitter in the same incision he used for the tag. A wire extends outside the fish’s body to transmit information.

Delonay puts a few stitches in the sturgeon. By the time the fish are caught again in July, the stitches will have dissolved. Sometimes, Delonay said, it’s difficult to tell they were ever there.

Finally, Delonay clips a part of the sturgeon’s fin for genetic information, then gives the fish a shot to prevent infection.

“Now the fish are instrumented and we can let them tell us what’s important to them,” Delonay said as he finished his bankside surgery.

After all the surgeries are completed, the crew spends hours putting the fish back in the same spot they were caught.

Sturgeon are highly adaptive to their environment but are struggling as the river has changed, Delonay said. “They’re very primitive,” he said. “They’re not dinosaurs, because they’re not reptiles, but they’re very old and very specialized at living in this environment. It’s a successful design by nature, but they rely on major rivers that we’ve done so much to.”

Dams, impoundments, contaminants, overfishing and regulation of many major rivers have decreased their populations, Delonay said.

Sturgeon generally eat invertebrates but the pallid also eat other fish, which makes them more vulnerable to environmental changes if the populations of their prey decline as well. A complex sensory system allows them to smell and detect changes in the water. Barbels, like taste buds, allow them to taste their food.

“That’s an important adaptation in a muddy environment like the Missouri River,” Delonay said.

“It’s a valuable river that is important to many different interests,” he said. “Millions live along it and everyone has a stake.”

George said the Corps recognizes that losing species like the sturgeon could be a dangerous slope.

“It’s like the spokes of a wheel, if one goes, it still works fine,” he said. “But then another goes and another and another until bang, it’s not working anymore.”