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The Trout Life Cycle
From Trout Are Made of Trees by April Pulley Sayre, text copyright 2008:
Trout are one part of a vast food web centered in streams and rivers. Trout require cool, clean water to survive. Trees shade streams, helping to keep the water cool. As stream water winds its way past fallen branches and rocks, it speeds up in some places and slows down in others. Fast-flowing water scours away dirt, leaving gravel. This creates the perfect nesting place for trout.
Fanning her tail and fins, a female trout sweeps away the top layer of gravel to create a pit—her nest. She lays several thousand eggs in the nest. A male trout swims over the nest and fertilizes the eggs. The male and female cover the eggs with gravel, then leave.
In about a month, the eggs hatch. Each young trout, called an alevin, has a yolk sac attached to its body. This sac provides nutrients. Once the sac is used up and absorbed into its body, the alevin swims out of the gravel. At this stage young trout are called fry.
Fry hide in quiet pools, among tree roots and branches that have fallen into the water. They eat aquatic insects—insects that live in the water—as well as tiny crustaceans and plankton. Many of these creatures feed on leaves that fall into the stream. As the trout grow they also feed on larger animals, such as snails, small fish, tadpoles, and adult frogs. When trout mature, they spawn, or mate, and produce a new generation of trout. These trout, like their parents, feed on the insects who feed on the leaves that fall from the trees near the stream.
Learn More About Stream Ecology
From Trout Are Made of Trees:
American Rivers: Learn about endangered rivers, endangered species, and how you can help conserve these natural resources.
Chesapeake Bay Foundation (CBF): Discover how to protect and preserve the Chesapeake Bay through CBF's environmental education program.
Peter B. Moyle, Fish: An Enthusiast's Guide (Berkeley, CA: University of California Press, 1993): This engaging and humorous book provides a succinct summary of fish biology and conservation for students and fish enthusiasts.
Project Wet! Worldwide Water Education: Learn about rivers, streams, fish, and wetlands, with lessons and activities to do with a group.
River Network: Find out how to make a difference in the quality of our rivers and the water we drink, with easy actions you can take at home.
Trout Unlimited: Help protect trout habitats by supporting this grassroots advocacy group.
UU environmental resources are the UU Ministry for Earth and the UUA Green Sanctuary Program.