Angling for Answers

When Chris Middaugh wades into a stream with his fishing pole and catches a smallmouth bass, it’s usually not for sport.

It’s for science.

Chris, a doctoral student in the Arkansas Cooperative Fish and Wildlife Research Unit in the Department of Biological Sciences, is studying the potential effects of climate change on smallmouth bass in Arkansas.

Chris Middaugh fishes for smallmouth bass in Osage Creek in Benton County, Arkansas.

“Specifically, I’m looking at how differing flow- and temperature-related conditions across stream types could affect smallmouth bass body condition and diet,” said Middaugh, who spent the last two summers collecting and measuring the fish in rivers and streams in the Natural State’s Ozark highlands.

“We’re focusing on smallmouth bass for a number of reasons,” he said. “Smallmouth bass are ecologically important in streams as a top predator, meaning they are at the pinnacle of the aquatic food chain. Smallmouth bass are adapted for cooler waters than other black bass species that exist in the same streams. This means that as stream temperatures rise over the course of this century due to predicted increases in climate temperatures, smallmouth bass will likely be stressed.”

Temperature-induced stress could lead to decreased growth, increased susceptibility to disease, or even death. It could also lead to a competitive disadvantage against largemouth bass and spotted bass.

Middaugh records the length of a smallmouth bass before returning it to the stream.

Chris said there has been a lot of work by other researchers examining how smallmouth bass range will likely expand further north or into higher elevations due to climate change. But relatively little work has been done examining the potential effects of climate change on smallmouth bass at the southern extent of their range.

“Arkansas lies at the southern extent of smallmouth bass’ native range, making it imperative to better understand how climate change may affect this species before we begin to see effects of climate change on smallmouth bass populations,” he said.

Chris and undergraduate researchers use hook-and-line methods to capture the fish, then weigh and measure them. During the past two summers they’ve sampled fish monthly at eight different stream sites – four in groundwater-dominated streams, and four in runoff-dominated streams. After the bass are caught, they wash the diet contents out of the stomach to sample what fish have been eating.

The lengths and weights of each fish are compared to a national average to determine the relative weight, and the stomach contents are all taken back to the lab where they are identified, dried, and weighed. All the fish are returned alive to the stream.

“So far, we have information from 687 fish,” Chris said. “We hope that this research will provide additional insight into how climate change could affect smallmouth bass at the southern edge of their range.”