The male leaves immediately, perhaps to search for another mate. The eggs absorb water, swell, sink to the bottom of the redd, and become slightly sticky. The female completes the nest by using her fins to shovel a load of clean gravel atop the fertilized eggs. Then she moves on to build another redd. Over the entire spawning season, females lay 400 to 600 eggs.
The eggs overwinter in the redd and hatch in early March. In 35-degree water, eggs hatch in about 144 days. At 40 degrees, incubation takes just 103 days. After hatching, fry remain in the redd until their yolk is absorbed. This can take 23 to 80 days, depending on temperature.
Small fry less than an inch long feed on microscopic crustaceans. At an inch in size, they switch to a diet of larval insects. At 4 inches they feed on adult insects, and finally switch to small fish when 8 inches long. Adult brook trout eat anything they can swallow. Their diet includes mostly fish, but also includes frogs, salamanders, snakes and even mice and shrews. Brook trout are sight feeders and feed most actively early in the morning and late in the afternoon.
The growth rate of young brook trout varies with latitude and habitat. In lakes and beaver ponds, brook trout can reach three to four pounds in three years. But in cold mountain streams, a 7-inch brook trout is considered a trophy.
Send questions and comments to Dr. Scott Shalaway, 2222 Fish Ridge Road, Cameron, WV 26033 or via my website, http://scottshalaway.googlepages.com.