Steelhead trout

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Map of native range of anadromous form-steelhead
Native range of steelhead, the anadromous form of O. mykiss

Steelhead trout is a name given to the anadromous form of the coastal rainbow trout (Oncorhynchus. m. irideus) or redband trout (O. m. gairdneri).[1][2] The steelhead are native to freshwater and ocean environments across North America, but have been introduced to every other continent except Antarctica. Steelhead use aquatic obstructions like vegetation, boulders, and fallen trees as protection.[3]

Description[edit]

During spawning, the fish will lay their eggs on gravel bottoms. The female digs out a hole called a redd. She then lays the eggs and a male fertilizes them. The females will then cover the eggs with the gravel. The eggs will remain like this until they hatch. Unlike Salmon, the Steelhead can spawn, then return to the ocean without any hardships. This allows the steelhead to spawn multiple times within its life.[3]

The freshwater form of the steelhead trout is the Rainbow trout. The difference between these forms of the species is that steelhead migrate to the ocean and return to freshwater tributaries to spawn, whereas rainbow trout do not leave freshwater. steelhead are also larger and less colorful than Rainbow trout. Steelhead can weigh up to 55 pounds (26 kg) and 45 inches (114 centimeters) in length. They can live up to 11 years and spawn multiple times.[3] The body of the steelhead trout is silvery and streamlined with a rounder head. The are black dots and a red or pink stripe running down the side of the fish horizontally. This silver color and round head is what gives the steelhead its name.[3]

The population of steelhead trout is in a state of endangerment across the United States of America, mostly caused by the blocking of waterways by the construction of dams. Human interaction has had considerable consequences on reducing the population of steelhead trout.[4]

When the fish are newly hatched, they feed on zooplankton and small insects. Once mature, the fish eat a large variety of food sources: fish eggs, insects, crustaceans, mollusks, small fish, and terrestrial animals.[3]

Conservation[edit]

There have been several conservation programs created since the near extinction of the steelhead in the 1940’s. The main reduction within the populations is mainly due to man made obstructions within river systems. This is usually caused by dams blocking access, or humans changing the river landscape for recreation and access to water. It is estimated that only 500 steelhead trout return to the Southern California watersheds. However, in other areas of the United States, steelhead can be seen as pests because they are an invasive species to the environment.[4]

Steelhead trout are endangered within the area of:

  • Southern California DPS

Steelhead trout are threatened within the areas of:[3]

  • California Central Valley DPS,
  • Central California coast DPS,
  • Lower Columbia River DPS,
  • Middle Columbia River,
  • Northern California DPS,
  • Puget Sound DPS,
  • Snake River Basin DPS,
  • South-Central California coast DPS,
  • Upper Columbia River DPS,
  • Upper Willamette River DPS

References[edit]

  1. ^ Behnke, Robert J. (2002). "Rainbow and Redband Trout". Trout and Salmon of North America. Tomelleri, Joseph R. (illustrator). New York: The Free Press. p. 67. ISBN 978-0-7432-2220-4.
  2. ^ "Steelhead Trout". NOAA Fisheries. National Oceanic and Atmospheric Association.
  3. ^ a b c d e f "Rainbow Trout and Steelhead". The National Wildlife Federation.
  4. ^ a b "Southern Steelhead: A Story of Recovery". California Trout.