Rapidly warming water temperatures in area rivers over the past 10 days are having a profound impact on fish behavior. Water temperature on the Mississippi River mainstem at Lansing was 39 degrees with a full moon ruling the night sky April 6. Moon phase can have a profound impact on fish behavior, especially during periods of seasonal change.
Walleyes and perch usually spawn when water temperatures reach 45 to 48 degrees in the spring. Spawning activity for these fish can last just a couple of days within three days of a full moon if the water has warmed into this range.
Over the past 20 years walleyes in pools 9 and 10 typically spawn between April 15-22. Two years ago those fat, green egg-cannons fired on April 1. This year the process has strung out over a week, just finishing now on the main river and over Easter weekend in tributaries like the Upper Iowa River.
Smallmouth bass are moving towards spawning areas today in a considerable hurry, as water temperatures are moving past 55 degrees in both Mississippi River backwaters and in streams like the Upper Iowa.
There is something magical about 55-degree water temperature during seasonal change in both spring and the middle of October when falling temperatures trigger bass into a major feeding binge to prepare for winter.
Studies completed by the Iowa DNR a few years ago indicate smallmouth bass migrate up to 12 miles when water temperature hovers near 55. Right now, these fish are moving back up into tributaries like the Upper Iowa to spend the summer. In October they will slide back down into the big river – often cruising right past suitable over-winter habitat in their “home” water.
Right now, these fish are staged in relatively small areas in tremendous numbers. These areas are on the quiet side of current seams at barriers like bridge pilings or large fallen trees. Find such a place and “fish on every cast” action is not out of the question. Soft plastics like the B-Fish-N Tackle Pulse-R in sassafras pattern and Z-Man Ned rig with a TRD plastic in colors “U” might expect are deadly on smallmouth bass when cruising in a staging area.
It makes little sense to leave fish once you’ve located fish. Switching to a slightly different presentation or color and targeting the same small area which already gave up a dozen or more fish can keep your rod bent for hours.
Smallmouth bass are vulnerable because they sometimes lack discretion, attacking anything which looks like food both now and again in October. They are honestly too valuable as a resource to be caught just once.
If you “free the fighter,” there is a good chance she will dance with you again later this year. If these fish are not released, you won’t have the opportunity to fish for her progeny in years to come.
You literally hold the future of fishing in your hands if you managed to tussle an egg-laden “bronzeback” into the net.
Clients often ask what my favorite fish species to catch is. The standard answer is “the one on the end of my line.” But if that scaly critter has a brown back and angry red eyes my smile is just a little wider.