It’s been a bad few weeks — or maybe years for fish — both here and in other parts of the country.
Carp and other species of fish have been reported to be washing up on the shores of Milford Lake this week for reasons that are not yet clear. Meanwhile, a Kansas State University researcher is discovering that the North American drought has caused dramatic changes in native fish communities in numerous rivers in several states.
The problem at Milford was reported by Carol Foveaux, a Leonardville resident, who said it appeared to involve bluegills, catfish and channel cat as well as carp. She said the dead fish appeared to have hemorrhaged.
Foveaux told The Mercury she first noticed the fish early last week while fishing with her father. Since she made the discovery, the fish have continued to die in “disturbing numbers” ranging in size from schools of small bluegills to 25-pound carp.
A representative of the Fish and Game office in Pratt said they are “aware that there is a kill affecting primarily common carp,” but added the department is not yet sure what is causing it. Biologists at Milford Lake were not reachable for comment.
Foveaux speculates that the fish are dying from something called Saporlegnia, a type of fresh water mold that causes a foamy slime on top of the water. It can lead to fish disorientation due to a depletion of oxygen in the water and also hemorrhaging of their internal organs.
Fish also appear to be having drought-induced problems in rivers and streams, both locally and in other portions of the country. “
A couple of key species that we have been studying have virtually disappeared where they historically were abundant,” said Keith Gido, a KSU professor of biology who researches fish ecology and conservation of aquatic systems.
Gido and his team study state and federal endangered and threatened fish species in river ecosystems, including the Arkansas and Kansas.
One example of what they have found: in the summer of 2011, Gido’s team observed more than 300 silver chub in the Ninnescah River in southern Kansas. In 2012, after the second consecutive year of severe drought, his team saw three silver chub during their sampling. They found zero silver chub in spring 2013.
“We are in a conservation crisis,” Gido said. “Our fish communities have changed dramatically and we are losing a lot of native species.”
Gido said two activities—river fragmentation and groundwater withdrawals—largely affect aquatic systems and native fish species in the Great Plains. When combined with the drought, these two activities result in dramatically reduced fish communities and lower species diversity.
River fragmentation occurs when barriers, such as dams, break up the long sections of connected river and create shorter segments.
Additionally, reservoirs and ponds behind dams often are stocked with nonnative fish, such as largemouth bass, that can move into the stream fragments and prey on native fish. This increases the effects of shrunken rivers.
“As the water levels decline, if you have a nonnative predator in the system, then the predators’ effects are much stronger and have a more drastic effect on fish,” Gido said. “We have seen a gradual decline in native diversity over time. The drought exacerbates any of the effects because with fragmentation, if the stream is dry and the water is lower, the fish are unable to move around a barrier.”
The researchers also are studying streams at the Konza Prairie Biological Station to understand how the presence of fish — particularly grazing minnows — influences the ecosystem.
The project is part of a large-scale $3.3 million National Science Foundation grant to study stream ecosystems.
Rose Schneider contributed to this article, as did the KSU News Service.