From Bounty to BreakdownWhat a 50% Decline in Missouri River Trout Teaches Us

With the recent trout number release for the Missouri river from Holter Dam to Cascade I felt

compelled to discuss one of the most preventable detriments to the trout of the Missouri River

that afford many of us to make a living from her bounty. While there is no one reason for the

over 50% decline in trout numbers from 2023 to 2024, this decline represents how delicate the

balance is to trout’s survival.

Respect the Redds: The Harmful Effects of Fishing for Spawning Trout on Montana’s

Missouri River

The Missouri River in Montana is one of the most iconic trout fisheries in the world. Known for

its prolific insect hatches, scenic landscapes, and year-round angling opportunities, it’s a bucket-

list destination for fly anglers from all corners of the globe. But beneath the surface of its clear,

cold waters lies a fragile and often overlooked reality—its wild trout populations are under

increasing pressure, particularly during the critical spawning season.

This post dives deep into the detrimental effects of fishing for spawning trout on the Missouri

River, why it matters, and what responsible anglers can do to ensure the health and longevity of

this beloved fishery.

The Lifecycle of Trout: Why Spawning Season Matters

To understand the impact of fishing during spawning, we first need to understand the trout

lifecycle.

Brown trout in the Missouri River typically spawn in the fall, from October to December, while

rainbow trout spawn in the spring, generally between March and May. During this time, trout

migrate to shallow gravel beds in riffles to lay their eggs. These nests, called "redds," are

carefully constructed depressions in the gravel where females deposit thousands of eggs, which

the males then fertilize.

For weeks—and even months—afterward, those eggs remain vulnerable in the gravel,

developing slowly and relying on clean, oxygen-rich water to survive. Disturbing these redds or

catching fish while they are actively spawning can have devastating consequences on the next

generation of wild trout.

The Missouri River’s Wild Trout: A Resource Worth Protecting

The stretch of the Missouri River below Holter Dam, often referred to as the “Blue Ribbon”

section, is home to thousands of wild rainbow and brown trout per mile. It’s one of the few rivers

in Montana where both species thrive naturally without the need for stocking.

This section is unique. It acts more like a spring creek than a freestone river, thanks to the

bottom-release Holter Dam, which regulates water temperatures and flows. These consistent

conditions make it an ideal habitat for wild trout—and an attractive target for anglers year-round.

But as more anglers descend on the river, particularly during shoulder seasons when fish are

spawning and water clarity is high, pressure on spawning fish has become a serious conservation

concern.

The Harm of Fishing During Spawning Season

1. Disruption of Spawning Activity

Targeting trout on their redds disrupts the act of spawning itself. When a fish is pulled off a redd,

it leaves its eggs exposed. In heavily pressured areas, those eggs may never get the chance to be

fertilized or may be exposed to predation and sediment displacement before the parent

returns—if they return at all.

Anglers often unintentionally step on redds while wading, crushing thousands of developing

eggs in a single misstep. Even if fish aren't being actively targeted, careless movement through

shallow gravel beds during spawning season can wipe out an entire years worth of reproduction

in localized areas.

2. Physical Harm and Energy Loss

Spawning is a physically taxing process for trout. They migrate, compete for mates, and expend

massive energy constructing redds and defending territory. Catching these fish during such a

vulnerable time can lead to stress-induced mortality, even if they are released.

Hooking, fighting, and handling a spawning trout adds strain to an already overworked fish.

Post-spawn mortality is well-documented, and angling pressure during this time can push fish

beyond their limit, leading to delayed death long after the angler walks away.

3. Artificially Inflated Catch Rates

Fishing for spawning trout often leads to artificially high catch rates. These fish are concentrated,

aggressive, and defending territory, making them easy targets for unethical anglers. While it may

make for an exciting day of fishing, it’s far from sustainable or sporting.

This behavior can also skew perceptions of fish populations, making it seem like the river is

healthier than it really is. When post-spawn mortality or poor egg survival impacts population

numbers in subsequent years, the consequences are felt by everyone on the water.

Spotting and Avoiding Redds

One of the most effective things anglers can do is learn to recognize and avoid spawning areas.

Redds are typically found in shallow, gravel-bottomed riffles or tailouts. They look like clean,

oval-shaped depressions in the riverbed, often surrounded by darker, algae-covered rocks.

If you see trout paired up in shallow water, especially if they appear to be chasing other fish

away or exhibiting erratic behavior, they are likely spawning. Give these fish a wide berth. Don’t

cast to them. Don’t wade through the area. Observe, learn, and move on.

Ethical Fishing Practices During Spawning Season

If you’re fishing the Missouri River in the fall or spring, there are plenty of ways to enjoy the

river while minimizing your impact on spawning trout:

• Fish deeper water: Focus on deeper runs and pools, where post-spawn trout often rest

  and recover.

• Use barbless hooks: Minimize handling and release fish quickly to reduce stress.

• Avoid sight-fishing in shallow riffles: If you can clearly see the fish paired up, there’s a

  good chance they’re spawning.

• Stay out of the river when possible: Fish from the bank or designated access trails to

  avoid trampling redds.

• Educate others: Many anglers simply don’t know the harm they might be causing. Share

  what you know and lead by example.

The Role of Guides and Outfitters

Guides and outfitters on the Missouri River play a critical role in shaping angler behavior. Many

are already leading the charge by refusing to target spawning trout and educating clients about

redds and river stewardship.

However, with increased pressure to produce fish for paying clients, the temptation to fish

vulnerable spawning areas can be strong. It’s vital that the guiding community continues to

uphold high ethical standards—and that clients demand it.

When booking a trip, ask your guide about their approach to fishing during spawning season.

Choose to support outfitters who prioritize the health of the fishery over short-term success.

Long-Term Impact: The Future of the Missouri River Fishery

The consequences of fishing to spawning trout may not be immediately visible, but over time,

they can lead to reduced fish recruitment, declining populations, and a less resilient ecosystem.

As water temperatures warm, flows become more erratic, and angling pressure increases, the

Missouri River will need every advantage we can give it.

Protecting spawning trout isn’t just about doing what’s right in the moment—it’s about

preserving the fishery for future generations. Whether you're a seasoned local or a first-time

visitor, how you choose to interact with the river matters.

Conclusion: A Call to Stewardship

Fly fishing is often described as a pursuit of beauty, connection, and respect—for nature, for the

fish, and for the waters we walk. But with that passion comes responsibility. On the Missouri

River, one of the greatest threats to wild trout is not pollution, invasive species, or even climate

change. It’s us—anglers who love the river but forget to fish it ethically.

Spawning trout are the future of the fishery. By choosing not to fish over redds, avoiding shallow

gravel beds, and educating others, we protect not just the trout—but the soul of the river itself.

So next time you wade into the Missouri, take a moment. Look around. Read the water. And

remember: the best anglers aren’t just those who catch the most fish—they’re the ones who leave

the river better than they found it.