December 2003





With the recent warm spell, what sort of precautions should those venturing out onto the frozen lakes and rivers to fish or do other forms of recreation take, if any?

Ice is never 100 percent safe, even during the coldest winter, so it's always a good idea to check ice conditions by calling a local bait shop before heading out. It's also a good idea to bring along a friend, rope, ice picks, a cell phone, and wear a lifejacket. With the recent mild winter weather driving on a frozen lake or river becomes especially hazardous. If it is absolutely necessary to drive on the ice, unbuckle seatbelts, roll windows down, and keep doors partially open for immediate escape should the vehicle break through. When trying to escape after falling through, whether on foot or in a vehicle, turn back in the direction from which you came, use your ice picks and kick your feet to pull yourself up onto the ice, and roll away from the hole to safer ice before standing up. Additional ice safety information, such as recommended ice thickness for foot and vehicle traffic, can be found on the DNR's Web site at Ice Safety Tips
Tim Smalley, DNR Boat & Water Safety Specialist


With winter finally here, and enough snow on the ground in most parts of the state to ride snowmobile. What are the educational requirements for the legal operation of a snowmobile?

Current statute requires anyone born after December 31, 1976 to take a safety-training course before operating a snowmobile on public lands or waters. Two courses are available. An 11-hour introductory course designed for the rider with little or no experience, which includes hands-on training, and an adult course for snowmobile operators 16 years of age and older. The adult course is offered as either a four-hour classroom session or on a new independent study CD-ROM. The adult course shows students the most common causes of snowmobile accidents in Minnesota, and how to avoid them. Information regarding snowmobile certification classes can be found on the DNR's Web site at Snowmobile Certification Classes.
Dave Rodahl, DNR Division of Enforcement recreational vehicle coordinator


Why does snow make different sounds at different temperatures when it is walked on?

The quality and amount of snow as well as air temperature all influence if snow will be noisy or quiet underfoot. Snow has air trapped between each flake, and when stepped on, those air spaces absorb sound. Dry, fluffy, new snow has more air trapped between each flake resulting in quiet footsteps. Wet, hardened, old snow has less air trapped between each flake, which means that less sound is absorbed resulting in noisy or squeaky snow. The amount of snow effects sound, too - the more it snows, the more air gets trapped, and thus, the quieter the snow is. However, snow only makes sound when the thermometer dips below 14 degrees Fahrenheit (minus 10 degrees Celsius). Temperatures above 14 degrees allow the snow to melt just enough to slip silently under your boots as you walk. So your boots can be a good indicator of just how cold it is outside in the winter.
Retta James-Gasser, Gooseberry Falls State Park naturalist


There recently was an incident on state-owned land where someone topped several thousand trees. What happens to the health of a tree when it is topped - whether it is for holiday trees, utility companies top them to avoid power lines or something else?

Although they'll look funny, trees should be able to survive the ordeal if topped correctly. The proper way to top a tree is to make the cut across the stem, or trunk, at a 45-degree angle to prevent water from pooling on the top of the tree. It's also important to leave plenty of stems (for deciduous trees) or needles (for conifers) on the part of the tree below the cut, and try to leave at least half of the crown. If you decide to top a tree, it is highly recommended that this take place in late summer or fall to prevent air borne diseases from causing an infection.
Rick Klevorn, DNR Forest Development and Tree Improvement Program leader


This summer the DNR conducted a study to learn the impacts of catch-and-release on Mille Lacs Lake walleye. What was learned?

Volunteers and DNR personnel fished Mille Lacs Lake from mid-May through mid-October and caught 848 walleye. A variety of factors dictated whether fish lived or not. For example, nearly all fish survived being caught and released when temperatures were less than 65 degrees, compared to one in six walleye that died in the heat of summer when most fish are caught in deeper water. Most of the fish killed in the study died as a result of some type of organ damage as a result of the hooking process. Mortality increased when walleyes were deeply hooked versus those hooked in the jaw or mouth. Walleye appear to have some resiliency to catch-and-release fishing, which may be due to the small hooks used to catch walleye - smaller hooks can reduce damage to internal organs. The study did re-enforce the DNR's suggested catch-and-release practices that encourage handling fish with care and fishing in a manner that reduces the number of deeply hooked fish. If anglers take these precautions they will help ensure others will enjoy the same experiences.
Keith Reeves, DNR Fisheries Research Biologist