No. Lakes classified as “bass lakes” are lakes where the conditions are right (or are predicted to be right in the future) to support high densities of largemouth bass. We do not take into account whether largemouth bass are in the lake at all or if they can get there. We also do not account for other species that may benefit from similar conditions (for example, bluegill). Finally, our predictions are based on projected changes in climate and simple lake variables, and represent one possible future scenario.
Importantly, the relationships between water temperature and fish identified in this study are based on correlations. We know that walleye natural reproduction is more frequent in cooler lakes, and we know largemouth bass reach high densities more often in warmer lakes. However, we do not know the reasons behind these relationships. Water temperatures in most Wisconsin lakes are not predicted to get too warm for walleye to survive in the foreseeable future. We can only speculate about the true cause for failed walleye reproduction in warmer lakes. We believe a number of factors may be at play, including potential mismatches between young walleye’s need for food and the availability of that food, increased competition and/or predation, increased need for food due to warmer temperatures, or a combination of these and other factors.
In the species classifications, we have categorized lakes based on their predicted probabilities of supporting natural walleye recruitment and/or high largemouth bass densities. In order to do this, we had to define a cutoff probability value that separated these categories. In this case, if the probability of supporting a species is 49% or more, we consider that lake to be supportive of that species. Sometimes, if the probability of supporting a species falls just above or below the 49% cutoff, the lake category can jump across the line and then back again due to small variability in the predictions that don’t represent any biological differences.
This is absolutely correct. Our predictions should be viewed as one possible scenario of what could happen in the future if the climate continues to warm. We based our predictions on a relatively pessimistic view of climate warming, so they can be viewed as a worst case scenario. The predictions are uncertain and could change if the climate warms more or less than predicted, or due to changes in fishing regulations, land use, other fish species, or angling pressure.