Ice-out dates for Minnesota keep moving up. This has been the case for the last 30 years. DNR biologists Mike Duval and Tom Jones discussed what the earlier ice-out dates mean for anglers. Here are a few highlights:
What are the implications of early ice out?
Duval: It will mean a variety of things: longer open water periods, warmer water temperatures, more evaporation, and more inter-mixing of lake water because the ice “lid” that capped the lake will have been removed for a longer period of time. Over time, Minnesota waters and their fish populations will tend to be more characteristic of states to the south of us.
Will warmer water improve or reduce fishing quality?
Jones: That depends. Temperature is a limiting factor for many fish species and, thus, a critical component of their habitat. Clearly, warmer water temperatures will be detrimental to tullibee, lake trout and other species that depend on cold water. Tullibee, for example, could disappear in the next few decades from some southern and central Minnesota lakes due to a combination of higher water temperatures higher in the top portion of the water column, and insufficient oxygen in the lower portion of the water column where temperatures are cooler. On the other hand, bass will do just fine because they can tolerate warmer water temperatures. In fact, bass abundance is already increasing across Minnesota. Growth rates should improve as well because of longer growing seasons. Overall, the early ice-out trend will create winners and losers, depending on the temperature habitat requirements of each particular species.
What’s the long-term forecast for walleye and northern pike?
Jones: In northern Minnesota lakes, higher water temperatures may benefit walleye and northern pike by increasing the length of the growing season. However, in southern lakes, temperatures may become too warm and lead to periods of mid-summer stress. If this stress becomes too severe, fish weights could decrease and walleye mortality could increase.
(More from the MN DNR website)
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