Alpena, Mich. — A recent fish die-off in northern Lake Huron has
resulted in more questions than answers.
The good news is that DNR fisheries biologists believe it was an
isolated incident. They have not received any additional reports of
dead fish washing up on shore following the initial incident in
late August, according to DNR fisheries supervisor Dave
The bad news is that they may never know exactly what happened
to upwards of 2,000 fish, mostly whitefish, carp, and sheepshead,
that washed up on a 16-mile stretch of Lake Huron shoreline south
“It seems to have come and gone without any new incidents of
mortality,” Borgeson told Michigan Outdoor News. “
DNR Fisheries Division personnel surveyed the shoreline of
Thunder Bay and the surrounding area to check on the numbers and
species of fish involved in the die-off. Borgeson said the fish
were all in advanced stages of decay, indicating they had been dead
for several days. That also means no carcasses were available for
testing at the state diagnostic lab in Lansing to determine the
cause of the die-off. Scientists need fresh flesh to perform the
“The trouble is that without fresh samples, it’s really tough to
tell exactly what happened to them,” Borgeson said.
The highest density of dead fish was found south of Alpena along
a 7-mile stretch beginning at Partridge Point. Some 1,500 fish were
found at this area alone.
“As you went out from there the density really dropped off, as
far as the ones that washed up on shore,” Borgeson said. “There may
have been a couple thousand, total.
“With an east wind like we had (prior to the fish washing up on
shore) it’s tough to pinpoint the exact location where the fish
came from. They could have washed into the bay.”
Most of the dead fish were bottom feeders, although Borgeson
said there may have been one or two salmon in the mix.
“When you get down to one or two fish of a particular species,
anything could have caused (them to die),” Borgeson said. “It was
mostly whitefish with a few carp, a few sheepshead, and a few
Although he would not speculate on the cause of the die-off,
Borgeson said that because the majority of the dead fish were
bottom feeders, he wonders if the die-off could be related to the
changing dynamics of the food chain in Lake Huron. Zebra mussels,
which feed on diporeia – an important food source at the bottom of
the chain — have been reported to have disrupted the food chain in
Lake Huron, and have been found in Thunder Bay in recent years.
“Fish kills are not uncommon to Great Lakes waters, and may be
caused by a number of naturally occurring factors and by
stress-mediated diseases,” Borgeson said in a statement. “The water
quality of Thunder Bay remains very good.”
He said commercial fishermen are catching healthy whitefish in
“I don’t think it was anything to be alarmed about. I think it
was an isolated incident both in time and location,” he said.
The Fisheries Division is still trying to collect samples from
the area of live fish that are visibly ill, or fresh dead fish, to
be sent to the lab for testing.
Anglers around Thunder Bay who observe sick fish or fish that
have recently died should put the fish on ice and call Borgeson at