Posted by Angie Hong | Posted in Aquatic Biology | Posted on 11-03-2013
In recent years, Asian carp have been hogging the limelight as they steadily push further north in the Mississippi and other rivers. It’s easy to see why the fish steal headlines. Bighead carp, which have been caught in the Mississippi River near Winona and in the St. Croix River near Bayport, are behemoths that can easily weigh more than 100 pounds. Silver carp meanwhile, mercifully still south of St. Louis, leap out of the river several feet in the air, injuring boaters and skiers. Even as we nervously hold our breath and assemble inter-agency task forces to keep Asian carp at bay, however, common carp have already infested many of our local lakes.
Though the name implies otherwise, common carp are not native to the United States. During the 1880s, they were brought in from lakes in Europe and Asia and intentionally introduced into Midwest waters as game fish. Today, they are found throughout the lower 48 states in hundreds of lakes, including many in Minnesota and Wisconsin. Masquerading as minnows, young carp are often inadvertently introduced to new lakes when fishermen dump their bait in the water. (In a similar fashion, non-native earthworms have infested many northern woodlands due to fishermen dumping their worms on land. For this reason, the Department of Natural Resources asks that all unwanted bait be dumped in the garbage.)
Common carp are a major problem for shallow lakes and wetlands in Minnesota because they destroy shallowly rooted aquatic plants and stir up sediment on the lake bottoms. As aquatic plant species decline, so do the desirable fish and waterfowl that depend on these plants for food. Without the plant roots in place, waves and schools of carp swimming by churn up muck from the bottoms of the lakes, making the water murky and releasing phosphorus and other nutrients back into the water. The phosphorus, in turn, feeds algal blooms that result in even worse water quality, as well as fish and waterfowl declines. It can be a vicious cycle.
Several local watershed districts, including Comfort Lake – Forest Lake and Ramsey-Washington Metro, have begun contracting with commercial fishermen to harvest carp during the winter from infested lakes. Because carp tend to school-up during the winter, a single harvest can capture 90% or more of the adult carp population in a lake. Equally important to capturing the adult carp, however, is to prevent the young carp from surviving the winter in wetlands where they are safe from sunfish. To address this issue in Bone and Moody Lakes, the Comfort Lake – Forest Lake Watershed District recently built low-flow fish barriers to prevent carp from swimming into connected wetlands and spawning.Yet another successful strategy for ridding our local lakes of carp comes from the Chisago Lake Lions Club, who began holding a Carp Fishing Tournament a few years ago. During a seven hour tournament last year, competitors caught 1.5 tons of carp in North and South Center Lakes. Steve Levey, the Lions Club member who started the tournament, likes to remind folks that “when you take out a female carp, you take out 1 million eggs.” Competition rules allow fish to be caught by any legal means, including bow fishing (the preferred method), spear fishing, rod and reel, and landing net. In addition to doling out prizes for the biggest carp caught and the most carp caught, the Lions Club crowns a Carp King and Carp Queen on tournament day and organizes several other fun activities. This year’s Carp Tournament will be held sometime in May. Levey hopes that more area Lion’s Clubs will be inspired to start carp tournaments of their own. “It’s fun with a purpose,” he says. I say, if you can’t beat them, eat them!