What Do “Shad” Lures Imitate When There Aren’t Shad?
Late fall is a weird time to be a bass angler in the Mountain West. The air’s got bite to it, surface temps are dropping fast, and every morning feels like one cold snap away from turning your boat into a fiberglass popsicle. My rig’s an inboard–outboard, so once the temps start to fall, I’m staring down winterization like it’s tax season.
I had maybe one good-weather weekend left. So I’m sitting on the back deck of my boat, space heater humming next to the outdrive, tying on gear for what could be the last bass-focused run of the year. I reach for a 4-inch Rage Swimmer in that classic “shad” pattern — pearl belly, gray back, little black dot on the shoulder — and I couldn’t stop wondering:
> “What do bass up here think this is when they bite it?”
Because if you’ve fished Utah, southern Idaho, western Wyoming, northern Nevada — basically the spine of the Mountain West — you know something:
We don’t have “shad.” At least not the shad that keeps bass fat and full in much of the country. The seasonal temperature swings here are far from ideal for traditional shad (threadfin) to survive.
Yeah, a few fisheries like Willard Bay are loaded with gizzard shad — big, oily, protein-packed baitfish that grow larger than the southern threadfin everyone talks about. But outside of Willard? Most of our lakes don’t have any real shad populations to speak of.
So why did bass in Hyrum, Pineview, Mantua, Twin Lakes, Jordanelle, Flaming Gorge — and everywhere else I fish — keep smashing this “shad” profile?
The rabbit hole was open, and I was determined to find out…
> “What do shad patterns imitate when there aren’t any shad? Is it rainbows?”
Silver flash. Light olive back. White belly. Thin profile. Hook a 10-pitch blade grass-jig trailer behind it and it even has that little tail shimmer.
And anyone who’s fished the Mountain West knows one universal truth:
> “There are a metric crapload of rainbow trout in our waters.”
Hate them, love them, trade them for canned tuna — they’re everywhere. Whether you’re in Utah, northern Nevada, southern Idaho, western Colorado, or the lower reaches of Montana, you’ve seen the stock trucks. You’ve seen the PowerBait armies. Rainbows rule the stocking schedules.
Welcome to Put-and-Take City
Fact: The Mountain West stocks an obscene number of rainbow trout every year. Utah alone produces roughly 11–12 million fish annually across its hatcheries (DWR Hatchery Overview, 2022). The majority are planted between 8–12 inches — “catchable” size.
Fact: Most of those caught-and-kept trout don’t survive very long. Creel survey data from Utah, Idaho, and Colorado show the majority are harvested within 2–6 weeks of stocking (Teuscher & Caputo 2001).
Fact: In shallow or warm reservoirs like Hyrum, fewer than 5–10% survive a full calendar year.
Think about that: if you see a 14-inch rainbow in late summer… you’re looking at a survivor.
Why Don’t They Spawn and Take Over?
A huge portion of stocked rainbow trout in our region are triploids — fish with three sets of chromosomes.
Short version: hatchery techs apply a brief pressure shock to fertilized eggs, which keeps the developing embryo from jettisoning its extra chromosome bundle. The fish grow normally but never produce fertile eggs or milt. Stocked rainbow trout are sterile (Benfey 2016, Reviews in Aquaculture).
Why do this?
They can’t genetically contaminate wild trout.
They spend less energy on spawning → slightly faster growth.
Managers maintain control.
That’s why stocked rainbows don’t take over reservoirs — even if conditions were perfect. And spoiler: reservoirs usually aren’t perfect.
To reproduce naturally, rainbow trout need cold, clean inflowing tributaries with gravel bottoms, oxygen-rich riffles, and stable spring flows. Reservoir shorelines rarely offer that.
So when you see hordes of rainbows in the Mountain West, remember: they’re biologically temporary.
How Many Actually Survive?
The answer boggled my mind! Across typical low-elevation waters in Utah, Idaho, Nevada, and Wyoming:
50–70% are harvested within the first month (creel data & angler-pressure observations).
Predation + warm surface temps knock that down further.
Fewer than 5–10% make it a full year (Idaho Dept. Fish & Game Report 01-17).
Those survivors? They go deep — into the thermocline — acting like wild trout.
And if you’re screaming in your truck right now, “Why don’t they just stock brown trout instead?” — don’t worry. I went down that rabbit hole, too. There’s a full breakdown in my article “Brown Trout: The Alley Cats of the Mountain West…”
Do Bass Actually Eat Baby Rainbows?
Absolutely — with nuance.
Fact: A 3–4 lb largemouth can eat prey up to ~⅓ its body length (Johnson & Martinez 1999). That means 7–12 inches is fair game.
Newly stocked rainbows cruise just under the surface. They’re disoriented. They glow like white neon in the water column. For the first 48–72 hours, predation by largemouth, smallmouth, browns, tiger muskie, and walleye spikes sharply. Even eagles, hawks, and osprey join the feast. Then the dumb ones get eaten, the smart ones go deep, and the buffet closes.
This stocking-window feeding frenzy is why early-season bass fishing can feel like cheat mode some years. Big predators know the calendar. If you want to understand how browns and other predators behave at night and during forage pulses, my article “Brown Trout: The Alley Cats of the Mountain West…” dives into exactly that.
So when a bass sees a slender silver-backed swimbait? It doesn’t think “shad.”
It thinks “rainbow snack.”
-HogHacker.com 10/24/2025
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If this clicked for you, you’ll probably like the next piece in the series:
“Why Rainbow Trout Are Prioritized by Mountain West Fish & Game” (how budgets, beginners, and natives drive policy)
“Brown Trout: The Alley Cats of the Mountain West” (why we don’t just stock browns everywhere)