A massive number of sturgeons died in Iowa during the drought and heatwave of 2012, and continued warming could put the ancient fish’s future at risk.
The die-off in the Mississippi River and its tributaries attracted the attention of a group of scientists from the Missouri Department of Conservation (MDC). Upon arriving at one of these fish-kill scenes, the group found evidence of the negative impacts of climate change.
The endangered pallid sturgeon and its relatives, the lake and shovelnose sturgeons, are from a prehistoric lineage, a species as ancient as they appear. A sturgeon will probably never win a beauty contest. This bottom feeder has large, scaly plates, and a broad, flattened nose with a few droopy whiskers. Populations of this species have plummeted over the last century due to river channelization and poor water quality. Now climate change is adding yet another threat to the sturgeon’s survival as river temperature levels rise.
During last summer’s drought, high temperatures caused a massive fish kill in the Des Moines River. The drought caused $10 million of damage for livestock producers and left thousands of shovelnose sturgeon dead. This caught the attention of MDC scientists like ecologist Quinton Phelps, who fears the same fate could await sturgeon in the Show Me State.
“We said ‘Man, what better to do than go up there and study this? We really need to figure this out.’ That’s a substantial economic loss that we’re talking about,” Phelps said. “In terms of the ecological loss, that was catastrophic. I mean, we are talking about thousands of shovelnose sturgeon dying.”
Phelps and a colleague grabbed a grad student and headed to the Des Moines River to study the effects of warming waters on shovelnose sturgeons. And they arrived right when another fish kill began, according to grad student Ryan Hupfeld.
“The river has been so degraded because up there there’s a lot of farmland and everyone is tiling, which has removed the riparian buffer and that actually causes a stream to widen and get shallow,” Hupfeld said.
Shallow waters heat up easily, so a string of days with triple-digit temperatures is bad news for sturgeon and other fish. Phelps said the river’s average summer temperature can go up to around 79 degrees Fahrenheit, which already stresses the sturgeons. But in the summer of 2012, water temperatures spiked to 93 degrees.
Due to the heat, sturgeons’ cells are unable to get rid of waste, swell and rupture. They are essentially bleeding internally and dying of hemorrhages. To Phelps, the fish-kill was more than just a smelly and disappointing event.
“The way I think about it is from a fish’s standpoint,” Phelps said. “This is a gruesome way to go.”
The Des Moines River incident is not isolated. Similar fish-kills have occurred in other rivers whose waters eventually flow pass Missouri, such as the Platte River in Nebraska, according to Jeff Runge from the U.S. Fish and Wildlife Service in Grand Island, Nebraska. His area of focus encompasses the entire Platte River, and the damage could be seen in large portions of it.
“We’ve covered approximately 28 miles, and we found 198 sturgeon. These sturgeons were decomposed to the point to where it was difficult to tell the difference between shovelnose and the pallid sturgeon,” Runge said.
It turned out the endangered pallid sturgeon were among the dead there, and just like in Iowa, other commercial fish were afflicted.
Back in Missouri, Quinton Phelps sees climate change as a problem that is not just limited to polar bears and melting ice caps.
“It’s a worldwide issue, I think that this study really brings home that, you know the problem is occurring much closer than what we typically expect,” Phelps said. “This isn’t the Arctic we are talking about. We are talking about Missouri. We are talking about Iowa. We are talking about the midwestern United States and bringing it right back here in our front room.”
This problem will only escalate unless measures are made to mitigate the detrimental effects of these warming waters. Both the MDC and USFW have already began management plans to save these ancient, dinosaur-like fish before they find themselves in even hotter water.