State district fisheries biologists examine a grass carp taken from Marrs Lake in Cambridge Township in Lenawee County.
michigan department of natural resources Enlarge
BROOKLYN, Mich. -- When the mail arrived at the Michigan Department of Natural Resources office in Lansing one day in the middle of May, there was something big and slimy and very ominous looking tucked inside a business-size envelope.
It was a picture of an Asian carp, three-feet long and a decade or two old, with its return address designated as Marrs Lake in Lenawee County. An anonymous angler had taken the fish while bow fishing and thought the state biologists ought to know about it.
The fish was a grass carp, one of the invasive Asian carp species, but not as notorious as its bighead and silver carp cousins. Grass carp do have a voracious appetite for vegetation and can destroy native plants and dramatically alter the habitat of native fish.
Marrs Lake is about 40 miles northwest of Toledo, sandwiched between State Route 50 and U.S. 12, near their junction just southeast of Michigan International Speedway in the Irish Hills area that is heavily dimpled with small lakes.
Operating on the assumption the photograph of the exotic fish was legitimate, biologists from Michigan's DNR quickly devised a plan of attack and assumed their battle stations.
"If there were grass carp in these waters, we wanted to know the effect on the fish community," said Todd Kalish, the Lake Erie Basin Coordinator for the DNR's Fisheries Division.
The Michigan biologists spent four days on the lake in June, gathering data for an in-depth assessment of the Asian carp problem, and of the health of the overall fish community. Their electro-shocking work captured another large grass carp, a 39-inch long 25-pounder, but the crew saw an additional biggie that eluded their nets.
"These fish are very spooky and very smart," Kalish said. "They'll see the net and turn the other way. This one was just too powerful and it swam right through the [electrical] field."
The MDNR crew was back on the lake in July, working with biologists from Central Michigan University to gather some 90 water samples on Marrs and several connected lakes, where it was feared the Asian carp might have spread.
The samples will be examined for environmental DNA, a painstaking process but one that will provide an accurate picture of how many grass carp are likely present in the waters, because each one has a distinct DNA structure.
The second round of electroshocking and netting on Marrs Lake produced a Nessie-like monster that weighed 50 pounds and measured 46 inches long. Grass carp can reach 100 pounds and more than five feet in length.
Both of the huge carp the DNR captured were females, and both were determined to be capable of breeding, but Kalish said the habitat on Marrs is not conducive to the reproduction of these fish.
"We don't know that they are reproducing, and we suspect that they are not," Kalish said. "Grass carp need specific conditions to reproduce, with flowing water, so there's really no optimal habitat there."
Marrs Lake's approximate 30 acres are traditionally home to a resident population of blue gills, largemouth and smallmouth bass, northern pike, and black crappies. Kalish said the in-depth study of the data gathered at the lake is not yet completed, but the preliminary indications are positive.
"The fish community appears to be healthy, but we'll have a better indication after we analyze all of that information," he said.
As for the huge grass carp, those fish had to be put in the lake at some point, but their origin remains a mystery. Biologists from Southern Illinois University that examined the fish estimated that the big carp were between 10 and 15 years old.
"But we don't know where they came from," Kalish said. "They were likely brought in to control vegetation."
These invaders reared their ugly heads in the St. Joseph River in Berrien County in July when a bow fisherman there took a 33-pound grass carp near the Buchanan Dam. That fish was also determined to be capable of reproduction.
Biologists fear that these rogue grass carp might have been sold as triploid, which have a very low probability of reproduction, when in fact they are not. The Michigan DNR is strongly against the use of triploid fish since the sterilization process is not 100 percent effective, and it is illegal to possess, transport, or stock live grass carp in Michigan, in both private and public waters.
Earlier this summer, an Arkansas man was charged with a dozen felonies relating to the possession and sale of live Asian carp in Michigan. He had 110 grass carp in his possession in tanks on a truck and was allegedly selling the fish, along with legal species such as bass and catfish, in parking lots around Michigan.
He was charged after allegedly selling a pair of live Asian grass carp to DNR officers working under cover. He is subject to a prison term of two years and fines of up to $20,000 on each of the counts he is charged with.
EHD OUTBREAK: Michigan wildlife officials have confirmed that an outbreak of epizootic hemorrhagic disease (EHD) has been fatal to hundreds of deer in eight counties in the south-central portion of the lower peninsula. The disease, which is transmitted by a biting fly, causes significant internal bleeding and is often fatal. With the rapid onset of EHD, deer weaken due to a loss of appetite, develop a high fever, are prone to excessive salivation, and eventually lose consciousness.
"To date, we have over 900 reports of dead deer across all counties," said Tom Cooley, wildlife biologist and pathologist for the Michigan DNR. "Although it is difficult to see so many dead deer, this is still a localized issue, and the regional deer population should not be affected."
Michigan has recorded outbreaks of EHD as far back as 1955, with losses of up to 1,000 deer in each occurrence in the affected areas. There is no known treatment for the virus when present in a deer herd, but there is also no evidence that the virus presents a danger to humans.
Contact Blade outdoors editor Matt Markey at: email@example.com or 419-724-6068.