Nature Nut: Streams run red

There’s something exciting happening in our local streams and rivers.

There’s something exciting happening in our local streams and rivers. Every year Kokanee Salmon (Oncorhynchus nerka) return to their birthplace from September to December to reproduce. Kokanee are a landlocked strain of Sockeye salmon, and the only Pacific salmon to mature in fresh water. Most Kokanee live in large lakes and, like the Sockeye, migrate from open waters to rivers and streams to spawn. But because freshwater environments are typically less productive than the ocean, Kokanee are much smaller than their anadromous counterparts, averaging about 22 centimetres in length. With silver streamlined bodies, Kokanee look like miniature Sockeye. Even when they reach sexual maturity at about four years of age, Kokanee mimic Sockeye in their dramatic physical changes in preparation for spawning. Males turn bright red and develop a hooked jaw and humpback, while females turn a dark purple-red and swell with eggs.

When this transformation starts, Kokanee embark on a journey to their hatching grounds to spawn. Some migrate great distances up small tributary streams; some simply spawn on the shores of the very lake in which they live. During spawning, a female uses her tail to swish out a nest in a calmer, gravelly location. She lays around 400 to 1,200 eggs, which are immediately fertilized by a single pursuing male. The female then uses her tail to cover the eggs with sand and gravel.  After an enormous amount of exertion and resource expenditure, the adult salmon conclude their life cycle and die. But where there is an end, there is also a beginning. As the bodies of the salmon decompose, they provide large amounts of nutrients to the aquatic ecosystem. This ensures that there is enough food for their offspring when they emerge. Kokanee eggs remain in the streambed nest while developing into Kokanee fry, which emerge from March to May. The fry ride downstream until they reach a lake in which to mature and begin the cycle anew. Many species and ecosystems depend on the completion of the Kokanee’s life cycle annually. It is important to ensure that the salmon are allowed to spawn without disturbance.

To see the red of the salmon run, try heading down to the Columbia River in Fairmont and Invermere, or Toby, Windermere, Abel or Holland creeks. Keep in mind that the Kokanee salmon run attracts visitors from all over, including bears, so be aware.

 

 

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