Spring Trout Behaviors

Understanding what trout are doing will help you catch more fish.

Do trout think or do they react to your offerings out of instinct? It’s a fact that all fish have gray matter between their ear bones. It is also well known that aquarium fish can be trained to eat. That much is true. The deeper philosophical question, however, is do trout have the ability to express conscious mental thought?

I would not go so far to advocate that trout have emotional needs, but one example of advanced behavior is swimming away from danger or hiding when approached by a predator. Another supporting argument for cognitive reasoning relates to how trout choose specific habitats for feeding and spawning. That trout have the ability to make these types of choices implies a certain amount of brainpower. More practically speaking, however, it suggests that paying more attention to their behaviors will allow you to occasionally outsmart them.

Consider that trout behavior is directed towards three related outcomes: survival, growth, and reproduction. These outcomes allow them to successfully complete their life cycle. There’s more of course. Specific environmental factors can influence their behavior, particularly in the spring when environmental conditions tend to be more variable. Want to increase your odds of success this spring? Start by reflecting on how trout behavior is influenced by their surroundings.

The Importance of Cover

Many streams and lakes remain closed to fishing over the winter, which leads to a temporary reprieve from pressure and makes trout less wary. This doesn’t mean that trout will be easier to fool though. They rely on cover for protection from terrestrial- and aquatic-based predators. Another way of putting it is that trout need cover to survive. Cover can take many forms, including overhanging vegetation, boulders, aquatic plants, and submerged wood. Water depth, turbulent current, and shade also provide cover. Nearness of cover is one factor in the selection of spawning sites by trout. Focus your angling efforts near cover and you will catch more trout.

Another way to increase your odds of catching spring trout is studying the flow patterns of your favorite stream or river. For example, is early-season flow dictated by melting snowpack, regional rainfall, or releases from an upstream storage reservoir? Figure these patterns out and plan your angling efforts accordingly. As an example, I focus my early season angling efforts on headwater streams because they drop and clear, i.e., become fishable, sooner than large rivers.

Flow volume or discharge is important for stream trout because it affects key habitat features such as water velocity and depth. During periods of high water, trout will seek refuge in areas of reduced velocity: feeder creeks, edge habitats, bottom of deep pools. Fish hold in these areas to save energy.  

Expect that springtime flows in your favorite stream or river will be higher than average, perhaps bank full. Also expect to find off-color conditions due to the presence of suspended sediments. We know that trout are predominately sight feeders. Reduced visibility means that the reactive distance between them and their prey is diminished. Consequently, dark fly patterns and lures with fluorescent color are more likely attract a strike, which leads to the next topic.

Food and Feeding Behavior

Scientific studies have shown that trout typically select food items that provide the greatest benefit in terms of calories and ease of capture. This principle of “optimum feeding” behavior implies that trout sense how or where to obtain the most food with the least amount of effort. To translate, trout must be efficient and smart when it comes to eating. Stream trout tend to reside in places where food can be delivered to them in the drift. Take time out from casting to observe how trout feed and you will find that they commonly set up station at the head of a riffle, on the outside of a channel bend, or other locations that could be considered “feeding troughs.”  

In still water, trout have to spend more time searching for food. Early season trout frequently cruise the shallow part of lakes and other water bodies, termed the “photic zone” or depth that light penetrates. These areas are favored by hungry trout because it is more productive, has abundant insect and crustacean life, and provides ample cover in the form of submerged vegetation.

It’s not all about bugs, though. All trout are carnivores and large trout will eat small fish where they are available. For instance, they will prey on young-of-year minnow and suckers that often crowd shorelines in the spring. Fly fishers capitalize on this occasion by favoring visible, streamer-type patterns such as Bucktails and Muddlers. Spin casters might work a small spinner or spoons along the edge of lake-side vegetation and stream margins.

Spawning Behavior

Another strong motivator for trout is reproduction. Knowing the reproductive cycle of trout in your favorite stream or lake will help you catch more fish. For example, are they actively seeking a mate or are they paired up? Is it redd building time or are they recovering from the rigors of spawning and eager to resume feeding? Changes in color and body shape of trout can provide clues about their spawning time, as can external features such as elongated jaw shape and teeth.

There are basic differences in spawning among the different trout species. For example, rainbows spawn on an ascending temperature profile in the spring. More northern populations tend to spawn later than those of southern latitude because of seasonal warming patterns. In contrast, brookies and browns are fall spawners. They initiate activity when water temperatures begin to drop from 50 F to 40 F.

One requirement for successful incubation of trout eggs is movement of water through gravel. Consequently, lake-dwelling trout will stage near upwelling areas and/or migrate to inlet and outlet streams to spawn. Stream-resident trout also have specific spawning requirements that relate to depth, gravel size, and velocity. Read up on these requirements and expect that trout will be nearby during the spawning period.

Water Temperature: A Controlling Variable

Water temperature is the single most important environmental factor that trout respond to because it dictates where they can live, grow, and reproduce. According to fisheries scientists, preferred water temperatures for trout range from about 56 F to 60 F. Because most water bodies are cooler than preferred temperatures in the spring, trout will frequent the shallows of lakes and streams, areas that warm up from sunlight more quickly. Being cold-blooded creatures, trout are not as active in the spring. This means your presentations should be slower and more deliberate than later in the year.

The development cycle of aquatic insects is also influenced by water temperature. Caddisflies stoneflies, and mayflies are predominately “univoltine” or with a single pronounced hatch during the year. In contrast, midgeflies tend to have multiple hatches over a longer period of time. Local fly shop websites are a good source for finding out about hatch times and appropriate patterns for your region of the country.

Universal fly patterns that include Renegade, Royal Coachman, and Adams are generally effective early on in the spring, while you may need to “match the hatch” at other times. A clear signal to bring out your box of “dries” is when you observe trout feeding. Otherwise, consider working a Prince Nymph or Wooly Bugger at depth. Insects are typically not active at the surface until sunlight hits the water and air temperatures warm.

Let’s Go Fishing

The bottom line to is all trout behave in specific ways that suggest they make thoughtful decisions. We know this because they reside where they can best conserve energy, while keeping an eye towards feeding opportunity and predator avoidance. Successful completion of their life cycle depends on it. It follows that you should consider the influence of key environmental conditions, such as temperature and flow, on the choices that trout must make before you string up your rod. Having this knowledge in your back pocket can make the difference between a successful day on the water and a day where you might come home “blanked,” as a Scottish gillie would say.