Water Works: Spring Hatches

by Bob Luck
Greetings from Hokkaido, Japan.  What I would like to write about this month is a beautiful river I fished yesterday for wild rainbows in the foothills of the Tokachi Mountains.  But this is not the Hokkaido Trout Unlimited newsletter, and, as President Yves reminded me yesterday, we are a coldwater conservation organization, not a fishing club.  Which means what I need to write about is bugs.
For most of my fishing career, my favorite order of aquatic insects was mayflies, with their elegant, upswept wings, stately bearing, and tragic Romeo-and-Juliet story of a single night of romance before embracing death. That changed six years ago when my daughter Marisa caught her first trout on a dry fly with an Elk Hair Caddis on the Rush River.  It was a beautiful 12” brown and she did everything right:  approach, cast, drift, set, land, pose, release.  You can guess which of us was more excited.  A few days later I ran into chapter members John Pogatchik, Pat Sexton and Ben Anderson who were clustered around a cell phone at a parking lot on the Rush, looking at photos of a 20+” Brown that John had caught and released.  Ben later sent me 40 (!) photos of the event, which shows you how excited he was. John told me I needed to try swinging wet flies during the caddis hatch and gave me a couple of Stop and Gos, which has since become my favorite wet fly.  With their mothlike appearance, Caddis may not be as lovely as Mayflies, but they are a blast to fish, and trout love them.
I fear that I may have fallen in love with Caddis just in time to watch them disappear from the streams in our area.  

I have been diligent about keeping a fishing log over the past 10 years, and entries recording spring caddis hatches are growing sparser.  This May was the worst so far.  I had only one good day of fishing caddis, on the Middle Branch of the Whitewater.  It was by no means a blanket hatch, but caddis emerged steadily from late morning through afternoon, and the trout were looking for them.  More typical was two days of fishing with Mike Rude, Jonathon Donager and Mike Rude on Trout Run, just before Mother’s Day.  The weather was perfect, and the stream was in great shape, but our high hopes of epic dry fly fishing were dashed when we saw only occasional caddis emerge from the water—not enough to interest the trout.  Exactly five years earlier, when I fished Trout Run with Steve Carlton, there was a strong Caddis hatch all day.
I can’t say that all hatches on all local streams are declining.  For example, I have noticed fishable hatches of sulfur mayflies on the Lower Kinni during the past two years for the first time since the early 2000s.  But my overall impression is that we have seen a dramatic decline in aquatic insect abundance, and I have heard the same thing from other anglers.  Aquatic insects don’t get much research funding or attention, but there is a small and growing body of scientific evidence pointing to declines as well.  There is probably no single cause, but one of the biggest factors seems to be the dramatic growth of Neonicotinoid insecticides as seed treatments on row crops.  Neonics are a highly effective neurotoxin for invertebrates--a teaspoon can kill a billion bees—and evidence is emerging of harm to vertebrates as well. Neonics are water soluble, and over 90% of the seed treatment washes into the soil, where it migrates to waterways. The use of Neonics skyrocketed in the early 2000s, about the same time as researchers found a massive decline in the Hex hatch on the Mississippi River.  Data collected by the Minnesota Department of Agriculture (MDA) shows that iconic streams such as the South Branch of the Root River and the Middle Branch of the Whitewater frequently exceed EPA standards for chronic harm to aquatic invertebrates.  Earlier this month, I spent a few days canoe-camping in the Boundary Waters, and was amazed by the prolific hatches of Caddis, Mayflies and Stoneflies on the Moose River.  Streams in the BWCA are much less fertile than our Driftless streams, but they also have little or no Neonic contamination.
You have probably heard that TCTU has joined the Campaign for Cleaner Seed, a coalition of organizations that is working for common sense regulations on Neonic-treated seeds in Minnesota (as of today, they are virtually unregulated).  We were not successful in getting legislation passed in the 2026 session, but we did raise awareness and we are already gearing up for the 2027 session.  Meanwhile, we have another chance to act.  Thanks to a successful lawsuit by The Natural Resources Defense Council and Minnesota Council of Environmental Advocates, by March 1st of next year, MDA must issue an order regarding whether their regulations are adequate to protect Minnesota’s natural resources from neonic-coated crop seeds. MDA has opened a comment period in which we and other organizations will have an opportunity to provide evidence.  Not all of that evidence needs to be peer-reviewed publications!  You can help TCTU to prepare strong comments by letting us know what you have seen going on with hatches.  Please take ten minutes to fill out this survey on hatches.  Thank you!
 
Bob