Dead muskies turning up in Detroit River
Written by Booth Newspapers   
Sunday, 30 April 2006 16:22

Detroit River anglers have reported hundreds, perhaps thousands, of muskellunge floating in the river, and state fisheries officials are unsure about the reason.

The fish appear to be adult muskies -- at least 30 inches in length -- and are being reported along the entire length of the river.

Gary Towns, the Department of Natural Resources fisheries biologist for southeast Michigan, said he was on the river recently fishing for walleye and saw nine dead muskies. He sent the DNR research vessel to cruise the river and the crew counted 41 dead muskies one day.
 
The fish, discolored and often covered with fungus or silt, are thought to be long dead, Towns said. He theorizes that the fish died in late winter or early spring, sank, and then as the water temperature rose, they began to decompose, became bloated, and floated to the surface.

A bacterial disease known as musky pox (Piscirickettsia) was discovered in the fish in 2002 and there was a significantly smaller die-off of muskies in 2003. But the mortality did not occur in 2004 nor 2005, Towns said.

Although musky pox appeared to infect a significant portion of the population, only a small number of the fish succumbed to the disease. Towns said that if the current die-off is related to the same disease, he is optimistic it will not significantly impact the area's musky population, which is quite strong. Current ecological conditions on Lake St. Clair -- clear water and substantial aquatic vegetation -- favor muskies, Towns said.

Lake St. Clair and the Detroit River boast some of the best muskie fishing in North America.

"We have contacted Canadian fisheries biologists and have asked that they monitor their side of Lake St. Clair," Towns said. "Early reports are that they have found some dead muskies along the southern shore of Lake St. Clair."

Towns said that while spring die-offs of fish are not unusual, often because of stress, he had no information that muskies were especially susceptible, though a Canadian biologist told him he had seen the phenomenon before.

Because muskies are among the first species to spawn in the spring, it would make sense that they succumbed to post-spawn stress, especially as the water temperature rose unusually quickly this spring, Towns said.

Towns said he has also received reports of dead bass on both Lake St. Clair and the Detroit River, but cannot conclude that the die-offs are related.

Because of the physical deterioration of the dead muskies, Towns said it would be unlikely that necropsies would help determine the cause of the mortality.

There is no indication that the fish are currently dying, Towns said.

He also said there is no truth to rumors circulating on the Internet that the fish were dying because of a hatchery mishap several years ago when an anti-viral agent was accidentally introduced into the hatchery system and is causing the mortality.

The DNR will continue to monitor the situation, Towns said.

 
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