River currents unlikely to advance zebra mussels to Minn. lakesMinnesota Department of Natural Resources officials annually sample the state’s large lakes, trying to get a handle on everything from the walleye population to the status of the invertebrates that kick start the food chain.
By: By Pat Miller, Forum News Service, The Jamestown Sun
BENA, Minn. — Minnesota Department of Natural Resources officials annually sample the state’s large lakes, trying to get a handle on everything from the walleye population to the status of the invertebrates that kick start the food chain.
Lake Winnibigoshish on the Mississippi River is one of the lakes on the list and last summer officials gathered 15 water samples which were analyzed earlier this winter.
In one of the samples the officials discovered something they were hoping never to find: two veligers (larval zebra mussels).
The veligers are evidence that there is a reproducing population of zebra mussels in Lake Winnie and it is likely that, in time, all of the lakes downstream from the popular fishing and recreational lake will also be infested.
Fortunately, Lake Bemidji and Cass Lake are upstream from Winnie and, according to DNR aquatic invertebrate research scientist Gary Montz, the mussel is not likely to advance against the current.
But that does not mean that the zebra mussels will never find their way to Bemidji, Cass Lake, Red Lake or the other area premier fishing waters.
“The zebra mussels won’t move upstream on their own and that’s good news,” said Bemidji Area DNR Fisheries Supervisor Gary Barnard. “But they are right on our doorstep.
“Many people take day trips from Bemidji to Winnie so having zebra mussels in Winnie is a concern for us.”
First discovered in Minnesota in 1989, the zebra mussel attaches to everything in the lake, including boats, docks, fishing line and native mussels. If a lake has high numbers of mussels over large areas they can filter the water to the point of impacting the food chain by reducing food for larval fish.
“We are doing everything we can to stop their spread or at least slow it but we haven’t been very effective,” Barnard said. “In the Bemidji we have to prepare as if the zebra mussel is coming.”
Among those preparations designed to slow the spread is revamping the water filtering equipment at the fish hatchery on the Mississippi River near Stump Lake.
“The upgrade is designed to filter things as small as the veligers out of the water,” Barnard said. “We use and transfer a lot of water (during the rearing and stocking process) and we don’t want to transfer veligers with the walleye fry.”
Lake Bemidji wasn’t among the lakes surveyed last summer but Red Lake and Cass Lake were. No evidence of the presence of an invasive species was found in either lake but it is impossible to give the lakes a clean bill of health.
“The studies take a very small sample size,” Barnard said. “We also assume that the zebra mussels will be in the lake before we know that they are there. We are taking preventative measures but everyone who is using the lakes and moving from one lake to another needs to be careful.”