Thousands of fish killed near Ashby

Bacterial infection hits Pelican Lake

Published Saturday, September 15, 2007

An acute bacterial infection has killed thousands of crappies in Pelican Lake near Ashby. Dean Beck, DNR Fisheries Supervisor, said that reports of dead and dying fish started coming in Sunday of Labor Day weekend.

Dead fish were floating onto shoreline and diseased crappie were lying on the surface of the water.

“Lab staff labeled the cause of death as Environmental Gill Disease,” Beck said. “Fish folks call the bacterial infection Columnaris, after the name of the bacteria Fexibactor Columnaris.”

DNR staff from the Glenwood area office captured some dying fish and shipped them to the DNR pathology laboratory in St. Paul to diagnose the cause of the fish kill. Beck was able to confirm the crappie died from a bacteria attacking their gills, preventing crappie from taking in oxygen from the water.

According to Beck, who is based in Glenwood and whose fish management area includes Douglas, Grant, Pope and Stevens counties, certain fish are more likely to be infected.

“Unfortunately, crappie is one of those fish,” he said. “Once an outbreak starts it’s highly contagious to other crappie and can spread quickly. It's

common to see some dead fish floating around the lake during the spring and early summer, but this was a very severe event.”

He said the DNR estimates thousands of crappie were lost to the disease outbreak. Most dead crappie were young, but 10- to 15-inch crappie were also observed.

“I’d much rather see these fish on the end of someone's line than feeding gulls,” Beck said.

The bacteria, according to Beck, is naturally occurring and not harmful to humans. He said that fish kills occur when susceptible fish are weakened by some environmental stress.

Beck indicated that Pelican Lake's crappie population was likely stressed from rapid water temperature changes that occurred during the week preceding the Labor Day weekend.

“Temperatures dropped into the mid-60s and rapidly increased back to the mid-70s,” he said. “Once their immune system weakens, the fish are vulnerable to such secondary infections. A Columnaris outbreak can be treated in an aquarium, but there aren't ways to prevent or treat an outbreak in a large lake.”

Beck said the DNR will complete some follow-up survey work to assure adequate survival of adult fish to rebuild population density. This was a big kill, but it would be very unlikely that it was a complete kill.

“Assuming good numbers of adult crappie remain, they'll be very successful in producing lots of young crappie in 2008 to fill the void created by the fish kill,” Beck said. “The kill was big enough that anglers will feel the pain, but crappie are resilient. They’ll be back.”

In a related issue, a large numbers of channel catfish have died in the

Red River. Cause of the fish kill has not yet been determined, but according to Beck, its likely the same bacterial bug.

“Scaleless fish such as catfish are also susceptible to bacterial infections,” he said. “Columnaris outbreaks are a problem — especially in catfish farms in southern states.”

A Grand Forks angler who spotted dead catfish over the weekend along the Red River notified wildlife officials. The dead fish have ranged in size from five inches to 30 inches. Some appear to have died recently, while others have been dead for several days. A few of the fish had lesions on their skin.

Lynn Schlueter, Red River fisheries biologist with the North Dakota Game and Fish Department, said he traveled about 15 miles of river by boat south of Grand Forks and encountered dead catfish the entire way.

He agreed with Beck and said the nature of the die-off suggests a disease such as Columnaris, a highly contagious bacterial infection that includes skin lesions.

“I don't know if it's my imagination or not, but the fish I've been catching lately seem sluggish,” Red River fishing guide Larry Kyllo said to the Associated Press. "We pulled in a 24-pounder here a few weeks back, and a bigger fish like that usually heads to the bottom. This one didn't even fight. It just laid on the surface.''