BEMIDJI-Lake Bemidji is one of the premier walleye fishing lakes in Minnesota and Department of Natural Resource Fisheries officials don't expect that to change, despite last fall's discovery of adult zebra mussels clinging to docks at the Northwoods Landing and on the south side of the lake, plus the remains of an adult in the stomach of a perch.
"Right now, Lake Bemidji is in good shape and we are not anticipating that the presence of zebra mussels will be negative. But we will continue to monitor it," said Bemidji Area DNR Fisheries supervisor Gary Barnard. "We can go out in a couple of hours at night during our fall electrofishing and monitor the recruitment of the young of the year walleye fry. Because of Lake Bemidji's importance as a fishery, we don't want to be surprised.
"It's unfortunate that zebra mussels are in Lake Bemidji. And it has been demonstrated that once they are established in a body of water, they can't be removed."
Zebra mussels have found their way into many neighborhood waters including Upper Red, Winnie and Cass Lake. Upper Red is a recent addition to the list while Cass Lake's zebra mussels have been established for a few years. DNR officials have kept track of the zebra mussels and their potential positive and negative impacts on Cass Lake and, so far, no drastic changes have occurred.
"We have seen some shifts in the different types of zooplankton species," Barnard said. "Zebra mussels colonize the bottom and can tie up the nutrients in the bottom zone. But, even though they are connected, Lake Bemidji and Cass Lake are two different water types. Cass Lake has had better water clarity than Lake Bemidji over the years and it has become even clearer after the zebra mussels.
"Lake Bemidji is more turbid and has higher nutrient (content) because of the city of Bemidji and the Upper Mississippi. We suspect that there will be some clarity of the water in Lake Bemidji (because of the zebra mussels), but not as much as we've noticed in Cass Lake."
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Lakeshore owners and beach-goers probably will experience the negatives of the zebra mussels more than anglers will. Fishermen might notice clearer water and, subsequently, might have to alter their angling techniques and schedules. Other lake users probably will have to deal with the zebra mussels more directly. The invaders often latch onto rocks at the beach, boats moored to docks and swimming ladders.
"Zebra mussels need a hard surface to attach to," Barnard said. "A sandy beach isn't as prime for them as a rocky shoreline or docks, boat lifts, or the bottom of a boat. And if you have a ladder on your dock, the zebra mussels will attach to them. And that won't be pleasant."
Anglers constantly have to adapt to changing conditions including cold fronts, calm water, fish migrations and weeds. The presence of zebra mussels represent just one more intrusion to deal with.
"Some vegetation may be deeper in the water column because of additional light (penetration) and that could affect the location of certain fish species," Barnard said. "Generally, what is bad for some species is good for others, and people will just have to adjust.
"But lakes don't necessarily follow the same patterns," Barnard said. "Each lake is different and you learn from each new introduction how a lake will respond and how the different species will respond."
For more information on Lake Bemidji, contact the Bemidji Area DNR Fisheries office at (218) 308-2339.