Stocked Trout

Do Stocked Trout Reproduce? (5 Stock Trout Questions Answered)

Stocking trout is big business in Michigan over 12 million trout were stocked in 2019. (source) With so many fish being dropped in the water you’d wonder if they reproduced in the wild and that the stocking programs could eventually be stopped. It turns out to be a complex question to answer. Morality and why the fish are being planted play a big part in whether the trout even have a chance to reproduce.

The question is legit though, do stocked trout reproduce? I have always wondered this and can stocked trout be used to repopulate a river or the lake?

Yes, the stocked trout can reproduce under favorable conditions and even help maintain the trout population in a water body. People have also noted that trout spawn over several seasons. But if they have genetic alterations to make them non-fertile (triploid trout), then they will not reproduce.

Generally, stocked trout are healthy and are used to help restock lakes and rivers for recreational purposes. So in this article, we’ll answer the question, “do stocked trout reproduce? We’ll also show you the conditions required for stocked trout to reproduce.

Where to Catch World Record Cutthroat Trout
Where to Catch World Record Cutthroat Trout

Do Stocked Fish Reproduce?

Generally, trout stocking in wilderness lakes in America started in the 1800s. Biologists continued stocking the lakes for over a century, mainly aiming to enhance and create sport fishing without considering the ecological ramifications. (source)

After the arrival of new environmental awareness during the 1960s, traditional fish stocking was questioned, especially after considering the adverse effects of introducing the hatchery trout.

Guide Recommended: In Yellowstone National Park, Lake Trout stocked in the area are considered an invasive species. (even after gillnetting over 3.4 million) Causing the native cutthroat trout population levels to decline to a level deemed “sensitive” (source)

A system that acknowledges the value of life replaces the utilitarian ethics of stocking trout. And in most cases, scientists genetically altered their genomes to make them sterile. The genetically modified trout fishes were exceptional, especially since scientists only introduced them for recreational purposes.

Fortunately, stocked trout can quickly adapt to a wide range of water bodies provided they have:

  • A year-round, ideal temperature,
  • Proper habitat,
  • An adequate supply of food.

And in most states, the stocked trout are introduced in reservoirs, lakes, rivers, and streams. (source)

Therefore, under the right conditions, a stocked trout get used to the new environment and even reproduces and spawn if not genetically altered. But for this to happen, some factors go into the equation; since they’re a type of salmon, they do need to spawn.

Therefore, they need to move upstream and spawn, but if introduced in a lake with no outlet, they may not be able to move upstream and spawn. Some of the factors that determine if the trout will reproduce include:

Place Where They’re Introduced

Stocking Trout in a River
Stocking Trout in a River

Most folks believe stocked trout are bred for tournaments and die off as soon as the derbies are over, which is not always the case. Fortunately, the trout belong to the Salmonidae sub-family; therefore, they inherit the salmons’ spawning behavior.

So instead of laying their eggs in shallow water like bass, they need to swim upstream and lay their eggs. Trout need to move upstream to spawn, but if the lake, pond, or reservoirs have no inlet, you may have difficulty getting them to reproduce yearly.

After all, they know they need a place with moving water to spawn. Therefore, breeding in areas with trapped water can be pretty hard, and anglers or predators may not catch them. On the other hand, streams and rivers have moving water, which can significantly affect their reproduction ability. So, if a few stocked trout make it upstream, you have a high likelihood of reproducing them.

Some of the More Popular States that Stock Trout

To help understand where trout are stocked by state and get a general feel for the numbers, I’ve created a table below.

StateNumber of Trout (2021)Website Source
Michigan4,921,799https://www2.dnr.state.mi.us/fishstock/
Montana3,786,547https://myfwp.mt.gov/fishMT/plants/plantreport
Utah3,739,490https://dwrapps.utah.gov/fishstocking/Fish?y=2021
Wyoming6,432,731https://wgfapps.wyo.gov/FishStock/FishStock

Are They Sterile?

There are situations when scientists introduce sterile trout to the local lake for recreational purposes. It can result in no spawning, even if the lake has an outlet or it’s a river. Generally, through genetic engineering, the two sets of chromosomes found in the wild trout can be modified into three sets creating a triploid.

Even though this process sounds dangerous, triploids are harmless, healthy, and normal, but they cannot reproduce or mate. They cannot affect the health of their predators or any angler who may carry some to their camping site for dinner.

In some parts of the United States, trout are considered an introduced fish; therefore, some agencies use triploids to prevent population growth. They only use them to provide food for their predatory native species.

Triploids can come in handy, especially when introduced to the lake for recreational purposes. After all, they tend to grow more significantly than the wild ones after surviving three years of their lives. So if they survive the typical fishing frenzy, they can grow and even become future trophy fishes. There is a term dedicated to these trout, which is hold-over.

Hold-over trout refers to stocked trout that have survived a couple of seasons by moving to colder and deeper waters.

Why Do We Stock Trout?

When do Rainbow Trout Spawn
Trophy Steelhead

Another common question that has baffled fly anglers for years is why we stock certain trout species. While the answer to this question correlates to specific situations, biologists stock trout for a few key reasons, and these include:

Recreational Purposes

People stock trout in a reservoir, lake, or river to provide anglers with an exceptional recreational opportunity. A good example is Utah’s stocking of rainbow trout for recreational purposes. In some states, including Utah, rainbows are stocked solely to guarantee anglers an exceptional fishing experience.

Remember, they’re adaptable, and wildlife officials stock them in a wide range of water bodies, including streams in valley reservoirs and mountain lakes. Other species stocked for recreational purposes include brook trout. (source)

Munching Other Fish Species 

Other than for recreational purposes, biologists tend to stock some species for scientific reasons like management tools. Scientists tend to stock certain species for a certain job, and in most cases, they do it for predatory purposes.

They can introduce some trout species to help maintain the population of some foraging fish species like golden shiner or Utah club. A great example of a predatory species introduced for population maintenance is the Bear Lake cutthroat trout.

Biologists have stocked cutthroat trout in Lost Creek, Scofield, and strawberry reservoirs to consume the Utah club. After all, the Utah club tends to get out of control if there is no predator to keep them in check. (source

Help Increase Certain Fish Population

Some fish species, particularly those native to a certain state, need stocking to maintain their population until their condition improves. Therefore, biologists tend to stock certain trout species whose population has been affected by human interference. Stocking overfished fish species can help maintain their population until they find the solution to the problem and prevent population decline.

How Can You Spot Stocked Trout?

If you’re wondering if the fish you have caught is a stocked or a wild one, then you’re not alone. Most folks can tell the difference between the two. Luckily, these two types of fish species have some unique telltale signs that can help you differentiate between the two.

  • Color: the streambed and wild lake trout tend to have more color genetically; therefore, they will be wild in color, just like the base of the stream. On the other hand, stocked trout tend to have more fleshy colors, with the new ones being tending to have more white.
  • Aggressive feeding: Stocked species are generally more aggressive in feeding and biting habits. It is because they grew up fighting each other for food; after all, they grew up in a small space. Wild trout and drift feeders are less aggressive.
  • Fins: stocked fish bred in hatcheries tend to have fin warping as they are bred in a crowded hatcher and transported in overcrowded trucks. Fin warping is not a dangerous issue, and if they overgrow, they may have to live with this issue for a very long time. (source)
  • Fin Clipping: Many stocked trout will have the adipose fin clipped signifying a stocked fish.  Some hatcheries will also clip the anal fin, but this isn’t as common.

Does Stocking Trout Affect the Local Population of Wild Trout?

Generally, stocking trout provides more opportunities for anglers while giving them a higher chance of surviving in the lakes. Unfortunately, stocking introduces several problems, and one of the leading problems is competition for food with wild species. Introducing a new species to the local habitat can affect the fishes and plants already living in the lake.

Therefore, when people introduce a new species in a place where wild trout already exist, they compete for food, resulting in the death of some wild species. They can also breed with the native species if they move upstream and lay eggs resulting in the pure line of the wild ones getting lost. Gila trout were affected by this issue after stocked rainbow trout introduction occurred in the streams.

In some cases, they have introduced a disease, particularly whirling disease, in the American rivers. The whirling disease was brought in the 1950s by stocked European rainbows. This disease was characterized by a curved spine, resulting in the fish moving in circles while swimming. (source)

What Are Hold-Over Trout?

Catching Monster Brown Trout
Catching Monster Brown Trout

If you have ever fished where fish stocking occurs regularly, you may have heard the name “Hold-Over” used. The term hold-over refers to fishes from past stockings that have migrated to deep and colder waters and thrived for years.

Generally, stocked trout design is not intended for them to live only for one year. Anglers usually catch the fish, which is why stocking occurs annually. But this doesn’t mean they can die off after living in the lake for a year. Some individual trout fishes can swim deeper into the lake and avoid capture for several years. Some can live in the water for several years after being planted.

Fortunately, this is excellent news since the longer they can survive in the deeper parts of the lake, the bigger they become. In some cases, they can end up being the trophy fish you will catch on your future fishing trips.

Can a Stocked Trout Become a Wild One?

Some people believe stocked trout can become wild once they have time to get used to the lake or river. Well, this is what most folks think. Some argue that they can adapt to their surroundings and take one or two habits or characteristics of the wild trout. But is this true?

The answer is no, stocked trout will always be stocked fish.  No amount of time can help them change and become wild. For example, the stocked and wild trout vary in color; therefore, this can’t change even after they have lived in the water for several years.

Remember, this is in their unchangeable genes; after all, the wild trout are the offspring of a gene pool that has existed in the lakes for generations. They adapted to a particular river system, including the seasonal lows and highs.

On the other hand, hatchery trout fishes are the opposite of wild ones. A considerable percentage of the stocked trout have been genetically picked and, in some cases, genetically modified to survive in a particular place.   


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One More Cast

Stocking trout is an everyday activity, mainly where fly fishing derbies occur. Therefore, it’s no surprise why we would wonder if stocked trout can reproduce. The simple answer is yes, but it will depend on several factors, including if they are genetically modified to create sterile triploids.

Hi David Humphries Owner of Guide Recommended. I love everything to do with fly fishing. Casting, Tying, YouTube, writing about it and even teaching. I’ve got a FREE video workshop teaching how to dry fly fish at this link How 2 Fly Fish

Sources

1. Edwin P. Pister, Wilderness Fish Stocking: History and Perspective, https://www.webpages.uidaho.edu/css496/secure/Readings/WFishStockingHistory.pdf/ Accessed June 16, 2022

2. Maryland government staff, Rainbow trout, https://dnr.maryland.gov/education/Documents/RainbowTrout.pdf/ Accessed June 16, 2022

3. Chris Penne, The Strategy and Science Behind Fish Stocking, https://wildlife.utah.gov/news/wildlife-blog/958-strategy-science-fish-stocking.html/ Accessed June 16, 2022

4. Steve Reeser, Wild or Hatchery Trout? https://dwr.virginia.gov/blog/wild-or-hatchery-trout/ Accessed June 16, 2022

5. Cherie Winner, Trout, https://books.google.co.ke/books?id=M8jZMcvJOn4C&pg=PA41&dq=how+can+you+catch+more+stocked+trout&hl=en&sa=X&ved=2ahUKEwjR—F1cD4AhXPQvEDHbKWBBUQ6AF6BAgDEAI#v=onepage&q=how%20can%20you%20catch%20more%20stocked%20trout&f=false/ Accessed June 16, 2022

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