Brook trout (Salvelinus fontinalis) are freshwater fish native to eastern North America, preferring cold, clear, and well-oxygenated water. These beautifully colored fish, sometimes called speckled trout, are often found in mountain streams and spring-fed ponds. Understanding their diet is important for their survival and role within the aquatic ecosystem.
What They Consume
Brook trout are opportunistic feeders, consuming various food sources in their aquatic environments. Their diet primarily consists of insects, both aquatic and terrestrial. Aquatic insects, such as larval and nymph stages of caddisflies, mayflies, and stoneflies, are key food items. They also consume adult aquatic insects emerging from the water.
Beyond aquatic insects, brook trout eat terrestrial insects like beetles, ants, grasshoppers, and moths that fall onto the water’s surface. Their diet includes small crustaceans like scuds and crayfish, mollusks, worms, and even small fish or amphibians. Larger brook trout eat smaller fish, including other brook trout, and occasionally small mammals like mice. This broad dietary range highlights their adaptability to available food.
Factors Influencing Their Diet
A brook trout’s diet changes based on environmental and biological factors. Habitat influences food availability; stream-dwelling trout might feed on drifting prey from upstream, while lake populations might consume more zooplankton or non-drifting invertebrates. Water temperature and vegetation also affect prey types and abundance.
Seasonality impacts food availability, shifting the brook trout’s diet throughout the year. During spring and summer, insect hatches provide abundant terrestrial and aquatic insects. In winter, they rely more on aquatic invertebrates as other food sources become scarce. Fish eggs can become a large part of their diet during fall spawning seasons.
A brook trout’s size and life stage also determine its dietary preferences. Young brook trout, or fry, feed on plankton and other microscopic organisms. As they grow, their diet shifts to small insects, then to larger invertebrates and small fish. Larger, adult brook trout consume a wider range of prey, including small vertebrates, and can still feed on smaller items if larger prey are limited.
Diet and Habitat Health
The diet of brook trout indicates aquatic ecosystem health. A diverse diet suggests a rich, balanced environment with varied prey species. Brook trout are a sensitive species, thriving only in clean, cold, and well-oxygenated water. Their presence and healthy populations signal good water quality and intact habitat.
Conversely, declining brook trout populations or a restricted diet indicate environmental issues like increased water temperatures, pollution, or habitat degradation. Understanding what brook trout eat and the factors influencing their diet is important for conservation efforts. This knowledge also assists anglers in selecting appropriate lures and flies that mimic the natural prey available.