Many people who are unfamiliar with the difference between wild trout and stocked trout naturally assume that they are the same thing. But the fact is, that there are many major differences between the two. Not only are stocked fish born in captivity, but they are also specifically bred for the purpose of providing anglers with easy-to-catch prey.
Wild Trout
Wild trout are born in the wild, without any human intervention. Their mere existence is a result of natural selection. They have adapted to the environment they are born into. They have dealt with being prey to other fish, and terrestrial animals. Yet despite their unassisted creation, they have survived and have lived harmoniously with the ebbs and flows of the streams they call home. The wild trout is considered to be a natural part of the diverse river ecosystem.
Without a question, wild trout, whether native or non-native, are very different than those raised in hatcheries. You can tell the difference between stocked trout and wild trout based on the color of their skin, the existence of damage to the skin or fins, how much fat content they have, their eating habits, and in many cases, the markings provided to them by the hatcheries.
Stocked Trout
Stocked trout are raised in hatcheries, and are selected based on their abilities to survive in the wild. They are released into the streams, rivers, ponds, and lakes as fingerlings, but they are not expected to last more than a single season outside of the hatchery.
Fingerlings
Most states have a specially designed conservation plan, that includes the annual restocking of natural bodies of water with a wide variety of trout. These fingerlings are born in hatcheries and are separated as eggs from other fish in order to give them a better opportunity to survive. They spend much of their young life within the safety and security of the hatchery before finally being released into the wild when they get to be about 3 to 6 inches in length. Once the fingerlings are released, the vast majority will spend their limited adult life learning how to survive. Unfortunately, very few of them will ever reach adulthood.
Holdovers
Those who make it past the first season, are often referred to as holdovers. To an angler, a holdover is a trout that had been stocked the previous season and has managed to evade capture for at least one season. Throughout the course of their first year in the wild, these holdovers, have dealt with predators, rough weather, a wide variety of stream conditions, and other natural phenomena which help them to develop a more natural appearance and habit. Those who are able to make it to adulthood, appear much like wild trout, but can still be identified by the hatchery markings.
Hatcheries
The sole purpose of stocked trout is to provide anglers with an easy-to-catch fish. That’s not to say that a true angler cannot catch wild trout, but, it creates the condition where the natural population has a better chance of surviving the fishing season. After all, not every single river is capable of supporting a large trout economy. If left unstocked, the remaining natural and wild fish would be quickly reduced to nothing.
The hatcheries, select trout that are more likely to survive in an artificial environment. They are genetically chosen for their ability to grow quickly and feed aggressively. The hatchery itself is filled with trout pushing and shoving up against one another in overcrowded troughs. As a result, the stocked fish grow quickly and develop deformities in their fins and tails. Their hunger and desire to feed constantly force them to grab hold of any bait that is dangled in front of them.
Ultimately, fish that are raised in hatcheries never develop the skills needed to survive in the wild. They see movement above, not as a threat to their existence, but rather as a source of food. While natural trout grow wary when they see a boat passing overhead, the stocked trout will race towards the boat in hopes of getting an easy meal.
Stocked vs. Wild Trout
There is a large difference between stocked and wild trout. The trout who are raised in hatcheries, generally have a different color to them, as a result of the pellet-based foods they are fed. Because of the overcrowded environment, stocked fish have damaged fins, snouts, and skin. Because they are genetically chosen for their ability to feed aggressively, they have a higher fat content than wild trout. They generally lack the ability to hunt their own food and will bite anything presented to them. But more importantly, stocked trout are marked by the hatcheries before they are released into the wild.
Color
Without question, the first thing that any angler will notice between a wild trout and a stock trout is the color of their skin. Fish who are raised in hatcheries are fed a diet of pellet-based food, that affects the overall color of their skin. While wild fish eat a variety of different foods, those who are raised in hatcheries, eat the same thing their entire life. As a result, many stock trout lack the vitamins, minerals, and proteins needed to survive and develop a more natural-looking appearance.
They have no need for camouflage in the streams because the hatchery provides them with a protected environment where they are able to survive with the least amount of effort. Because of this, stocked trout have a duller, brownish-gray appearance than wild trout.
Damaged Fins or Skin
The hatcheries are confined, and the fish are raised in overcrowded troughs with hundreds of other fish. Because of their close proximity to other fish, and the hatchery walls themselves, stocked fish generally feature tails and fins that have been shredded, and scrapes that can be seen all along the length of their bodies. They spend most of their young life, being pushed up against the concrete walls of the hatchery, and being nipped at by the other fish. While most of the damage caused by being raised in a hatchery will heal over the course of a single season, very few trout make it that long. Those that do, will still feature the hatchery markings, like intentionally clipped dorsal and adipose fins.
Fat Content
Stock trout are specifically chosen because of their ability to feed aggressively and grow larger in the least amount of time possible. Because of this, the fish who are raised in hatcheries, generally develop excessive amounts of fat content when compared to wild trout. The fish themselves, are raised in an environment where they do not have the ability to swim around and get the exercise they need. Instead, they are fed one meal after another, after another, after another. The pellet-based food they are fed is generally high in fat which results in a disproportionate development of fat around the stomach area. Most anglers refer to these types of stocked fish as footballs or even pellet pigs.
Eating Habits
In the wild, trout eat differently than they do in captivity. A wild trout will spend much of its life having to then for itself. Not knowing when it will have another opportunity to eat, wild trout consume a wide variety of different bugs, worms, fish, and even other fish eggs. The fish who are raised in hatcheries on the other hand, never learn to fend for themselves because their food is always given to them. They are unfamiliar with things like flies, eggs, and other popular baits that can be used to catch wild trout. As a result, most hatchery trout will not even attempt to strike at a hook that has been baited with a fly, fish eggs, or worms.
It generally takes a stock trout several weeks to learn how to fend for themselves in the wild. Over that time, they can get very hungry and will snap at just about anything. It is a crucial time for most fish that were raised on a farm. Because of this, it is best to wait several weeks after a pond or river has been stocked before you begin to fish there. By the time you cast your line in the water, those stocked trout will grab a hold of just about anything.
Markings
Although not all states mark trout that have been raised in hatcheries, most states do. The local Department of Natural Resources, which is responsible for operating the various hatcheries, not only marks the trout raised in their hatcheries but also posts notices in the popular fishing areas, identifying how the stock trout are specifically marked. This allows any angler to determine quickly whether they have a wild trout or one that grew up in a hatchery.
There are a number of ways that hatcheries can mark a trout. The most common way of marking a trout is to clip certain fins. The adipose and dorsal fins are the most commonly clipped fins. Depending on the hatchery, a single fin may be clipped, or multiple fins may be clipped. Some hatcheries are also known to mark trout by cutting the fish behind the eyes, or along the gills.