August 2006





Once the Boundary Waters Canoe Area Wilderness fire is out, how long will it take for the burned areas to green up?

Some areas burned by the Cavity Lake fire will begin to green-up immediately. Because this is a drought year, many areas may not significantly green-up until moisture is available to germinate seeds or start new growth. Gradually the land will renew itself and in a few short years, trees, shrubs, blueberry bushes, and underbrush will cover most of the landscape. In areas where the fire burned very hot, destroying much of the shallow soil, it may be years before much growth is noticeable. The land will start with lichens and mosses to reestablish shallow soils.

Jean Bergerson, Minnesota Interagency Fire Center information officer


The DNR is in the process of determining pheasant population in the state's pheasant range. How is this number determined?

Every year during the first two weeks of August, the Minnesota DNR uses roadside surveys to estimate pheasant abundance. These surveys entail counting all pheasants observed while driving each of 152 survey routes - one to four routes per county - in Minnesota's pheasant range. DNR wildlife staff survey these routes in the early mornings on days with clear skies, light winds and heavy dew. Because pheasants are difficult to count, techniques used to determine population estimates for other wildlife species does not work with pheasants. Thus, the annual August roadside surveys do not provide a total census, but rather an index of relative abundance. This information is then used to monitor changes in the pheasant population over time. In 2005, for example, 890 pheasants were counted on 800 survey miles in south-central Minnesota. That yielded a population index of 111 pheasants per 100 miles. This value was 51 percent higher than the 2004 index for the same area. The results of the survey are reported in early September and provide a good forecast for the upcoming pheasant hunting season.

Kurt Haroldson, DNR wildlife biologist


Our hot, dry weather certainly affects lake levels, but can it also impact fish populations?

Generally, fish populations are minimally effected by hot, dry weather in deep, permanent fish lakes. In these lakes, fish are able to move to cooler, deeper water if they desire. However, in shallower lakes, the entire water column may warm more than usual, stressing some fish species. Warmer water has a lower capacity for dissolved oxygen - critical to fish survival. Stressed fish may also be more susceptible to fish diseases and parasites. If dry conditions persist for several years, some critical shallow water areas may be left high and dry, and no longer available for fish spawning or for use as nursery areas by young fish. Fortunately, fish are very resilient and quickly bounce back to normal when rains come and temperatures cool.

Tim Goeman, DNR Regional Fisheries manager, Grand Rapids


By mid-summer many lakes, rivers and ponds have turned green or have a green hue to them; the body of water may also have an odor to them. What causes this? And, is it correctable?

By mid-summer many lakes, rivers and ponds turn green due to the growth of small microscopic plants in the water called algae. Algae grow in all bodies of water when light and nutrients levels are sufficient. In many lakes, algae abundance is determined by the amount of phosphorus dissolved in the water. The more phosphorus present, the more abundant algae become and the greener the water gets. There are many different types of algae. During the mid-summer one particular group of algae, called blue-green algae, are often particularly abundant. As it becomes abundant, a strong musty or earthy odor many occur. Algae that have died and are decomposing cause the odor. Because algae abundance is strongly dependent on the amount phosphorus available, the best strategy is to improve land-use practices to prevent phosphorus and other nutrients from getting into our lakes and ponds.

Dave Wright, DNR Invasive Species Program supervisor


How do I know if it is a minnow?

Not all small fishes are minnows; many are the young of other fish. A number of characteristics serve to separate small fish from true minnows. All minnows have naked heads except during breeding season when mature male develop many hornlike bumps, called tubercles. Some minnows also develop bright colors during breeding season, as suggested by such names as redside dace, redbelly dace, rosyface shiner, red shiner and redfin shiner. A single dorsal fin with fewer than 10 soft rays is characteristic of all native minnows. In the introduced carps and goldfish, the dorsal fin has a hard ray and more than 10 soft rays. Minnows lack teeth in their jaws but have specialized teeth in their throat - pharynx - region. These pharyngeal teeth are useful in identifying the various minnow species.

Roland Sigurdson, DNR MinnAqua Program


DNR Question of the Week Archive