Where Trout Begin: Why We Must Protect the Spawn.

The Missouri River below Holter Dam in Montana is home to a thriving trout population, made up of roughly 95% Rainbow Trout and 5% Brown Trout. As spring arrives and fish begin to spawn, it's important to remind anglers of the impact fishing can have during this sensitive time. While there are many factors that contribute to fish mortality and poor recruitment, targeting spawning trout is widely regarded by experts as one of the most harmful—and most avoidable—practices. Although some rivers and streams are closed during the spawn to protect these fish, the Missouri below Holter remains open, making angler awareness and discretion all the more crucial.

 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 hundreds of brown trout per mile. It’s one of the few rivers in Montana where both species thrive naturally despite the 95% rainbow dominance.

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 year's 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.

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, a boat or a designated access trails to avoid trampling redds.

·       Educate others: Many anglers simply don’t know the extent of 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 during spawning seasons, 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 neglect 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 cast a line 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.