8/9/2007

Spiny waterfleas still spreading on Canadian border waters

The invasive spiny waterflea continues to spread and become more abundant along the United States - Canada border waters. In response, the Minnesota Department of Natural Resources (DNR) has designated several additional waters as "infested waters."

In St. Louis County, newly designated infested waters are Crane Lake, Kabetogama Lake, Little Vermilion Lake, Sand Point Lake, and a portion of the Ash River, upstream of Kabetogama Lake. In Cook County, Caribou Lake located in the Boundary Waters Canoe Area Wilderness just west of Pine Lake is now designated as an infested water. Also in Cook County, a DNR fisheries crew from Grand Marais recently found spiny waterfleas in Gunflint Lake and suspect they could be in other waters connected by the Granite River. The new designations also include most tributaries on the U.S. side of the Rainy River and Lake of the Woods - usually upstream to the first road.

This summer, spiny waterfleas are very abundant in Rainy Lake, Rainy River and Lake of the Woods that were designated earlier in the year.

"Anglers are reporting the abundance of the waterfleas to DNR fisheries staff and conservation officers after seeing them on the down riggers and other gear," according to Mike Larson, fisheries supervisor in Baudette.

Once designated, state regulations help prevent the spread of spiny waterfleas to other waters. They prohibit the transport of water, prohibit harvest of bait for personal use, and restrict the commercial harvest of bait from those waters, similar to zebra mussel-infested waters in other parts of Minnesota. Commercial harvest of bait will still be allowed in Lake of the Woods, tributaries of Lake of the Woods, and the Rainy River by licensed minnow dealers who have received special training and are take special precautions required by their permits.

"Spiny waterfleas can spread by sticking to fishing lines, downrigger cables, anchor lines boats, fishing or other gear, and even seaplanes can become contaminated," said Gary Montz, DNR aquatic invertebrate biologist. "It is important to clean off, dry, and drain boats and equipment before using in another lake or river."

Spiny waterfleas collect in masses that resemble gelatin or cotton batting with tiny black spots, which are the creatures' eyes or eggs. Individual animals are difficult to distinguish without magnification because they are only one-quarter to three-eights long.

The waterfleas can have different harmful impacts in different lakes. The waterfleas compete with small fish for food called zooplankton. While larger fish eat them, tiny fish may not be able to consume this invader. In certain types of lakes, waterfleas can change the species and numbers of zooplankton, which can harm those lake ecosystems.

Before leaving the water access, boaters and anglers should do the following to stop aquatic hitchhikers:

- remove aquatic plants and animals, including gelatinous or cotton-batting-like material from fishing lines, downrigger cables or anchor ropes

- drain water from livewells, bait containers and bilges by removing the drain plugs; those who want to keep live bait must replace lake or river water with tap or spring water.

Boaters and anglers should also:

- dispose of unwanted live bait in the trash

- spray the watercraft and gear with hot high pressure or hot tap water (above 140 degrees F or 60 degrees C for at least one minute) before transporting to another water - or - dry the watercraft and gear thoroughly for at least five days before transporting to another water.

Information regarding the spiny waterflea in U.S.-Canadian border waters may be obtained at any Voyageurs National Park visitor center, or the DNR Fisheries Section offices in Baudette or International Falls.

Spiny Waterflea Watch identification cards are available by calling the DNR Information Center at (651) 296-6157 or 1-888-MINNDNR (646-6367), or the University of Minnesota Sea Grant Program at (218) 726-8712.