Brown Trout Spawning Education
In the last few years, Calgary River Valleys has held pop-up education stations on the Peace Bridge during October, when the Brown Trout that live in Calgary’s rivers are spawning. Many of the people we interacted with didn’t know that the spawning of Brown Trout was an annual event that can be easily seen from the bridge, although it does help to use polarized sunglasses, which makes it easier to see through the water.
In the image on the left, the lighter coloured areas in the river gravels are the spawning nests. These are created by the female Brown Trout. She uses her tail to clear away the sand and silt from the rocks, and creates a small hollow in the gravels. When she’s ready, she will lay her eggs in the hollow, and the male Brown Trout that is waiting nearby will fertilize them. Then, the female will swim slightly upstream, and use her tail again to swish upstream gravels onto the fertilized eggs to protect them under a mound of clean gravels. This creates the identifiable 3 elements to a Brown Trout redd or spawning nest for the current year: 1) a clean spot of relatively small sized gravels, 2) an upstream hollow in the gravel, and 3) a downstream mound.
In the image on the right, the dark shapes are Brown Trout preparing to spawn. The female is usually the upstream fish, and the male will usually wait slightly downstream.
Frequently Asked Questions:
Q) Where do the Brown Trout live the rest of the year? A) They live in the Bow & Elbow Rivers
Q) Why aren’t they red? A) They aren’t like salmon, which turn bright red & die after spawning; they stay the same colour year-round, and carry on living after spawning.
Q) When do the fish eggs hatch? A) The eggs stay under the mound of gravels over the winter and hatch in February or March; they get the nutrients they need, including oxygen, from the river.