In the Field with Jeff Kurrus – An Afternoon at Wehrspann
Wehrspann Lake in southwestern Omaha has one of the city’s best hike/bike trails in eastern Nebraska. With more than 5 miles of paved trail next to water, tallgrass prairie, and an array of wildlife, the area is perfect for an afternoon jaunt. But while Madeline, Eli, and I were there, strollers and stuffed animals in hand, I came across one question I didn’t know the answer to. Hopefully someone out there (Hint, Hint Daryl Bauer) can answer it for me:
When the water level at a lake is dramatically down but has been for a long time (say, over a winter like we have now), what does that do to fish patterns in that particular body of water? Should catching fish be easier?
That day’s walk was also, as it always is, a nice time to bring a camera along.
JK
Madeline with a freshwater snail shell.
Low water at Wehrspann Lake.
Milkweed along the trail at Wehrspann Lake.
Nice windtesters in that last photo!
Jeff,
Of course low water levels have an impact on fish populations—FISH NEED WATER! Once the water has been low enough for long enough, fish populations have to adjust, downward. There simply is less habitat, less volume of water, and usually less productivity, and all of that adds up to less fish. Decreases in fish populations can happen as fish migrate out of a body of water, with declining water levels that might happen as fish migrate out of a reservoir with irrigation releases, or populations decline because mortality rates increase. Increased mortality with low water levels will be realized as increased natural mortality, but it can also be increased fishing mortality. Fish crowded into less water with less available prey are usually easier to catch—“fish in a barrel”, just on a little bit larger scale.
Fishing patterns change with low water levels, no doubt. Generally, fish migrate away from shorelines and towards deeper water as water levels drop. Again with less habitat available, there can be increased competition for what habitat is left and increased competition for prey resources too. Declines in water levels often mean changes in water quality which also will influence fish behavior and fishing success. Some of those changes can be hard to predict, but you can be sure that fishing conditions change when water levels change.
Now, if you are still reading, I must say something about the snail that Madeline is holding in that picture. Yes, that is a freshwater snail, but it is NOT a native species. What she is holding is either a Japanese or Chinese Mystery Snail. No, the snails are not a “mystery” nor is it a mystery what they are; they are literally called Mystery Snails. You can learn more about those and other invasive aquatic nuisance species in Nebraska here, http://snr.unl.edu/invasives/invasiveaquatic.htm . The Mystery Snails have been available through the pet trade, but we also know that folks have moved them around and introduced them to a number of waters in eastern Nebraska. A practice which is very much illegal!!! I cannot tell you for sure what impact the Mystery Snails might have on our native species or ecosystems, but I do know we would rather not find out!!!
Daryl B.
Thanks Daryl.
I hoped you would be reading. Great information.
JK
Makes me think of escargot.