Steelhead

Steelhead trout (Oncorhyncus mykiss irideus)

So one may ask, “What is a steelhead?” A steelhead is a coastal rainbow trout with an alternate (anadromous) midlife strategy different from that of other trout. Steelhead trout and Coastal rainbow trout are essentially the same fish. Coastal rainbow trout have the genetic predisposition to become anadromous, like their salmon cousins, or remain in fresh water as “residents” for the rest of their lives. This ability is unique to coastal rainbows; other varieties of rainbow trout do not have this ability. Coastal rainbow trout have been observed to have 32 different type of life history strategies about their time in fresh water, salt water, spawning time etc. for the duration of this page we will refer to coastal rainbow trout as steelhead trout.

Steelhead trout are likely the most iconic fish of the Russian river watershed. The Russian river had 20-65,000 trout returning annually. The third largest runs of steelhead in California after the Sacramento and the Klamath. The steelhead fishery was world renowned up till the 60’s. Historically every stream in the watershed was habitat for steelhead. With the increase of urbanization, agriculture, and river modifications this once healthy fishery has dwindled. Efforts to increase steelhead in the Russian have been in place since 1870 and still continue today with the Warm Springs hatchery at the base of lake Sonoma. Russian river steelhead belongs to the Central Coastal California (CCC) distinct population segment (DPS). 


a pair of male Steelhead

Life History

Steelhead show a tremendous variety of juvenile and adult life history compared to other salmonids, this will be the most general life history for the fish of this watershed.

  • Steelhead begin their lives as eggs under gravel, hatch as alevin and emerge as fry after they absorb their yolk sack.
  • Steelhead spend 1-2 years in their natal streams
  • As steelhead begin to smolt, go through a series of physiological changes to prepare for entering the ocean, they may utilize the estuary for a period before entering the ocean.
  • Steelhead spread far and wide in the pacific where they will spend 1-2 years
  • Steelhead return to the Russian river in late December-March depending on winter storms to increase flow for access to tributaries
  • They spawn and quickly return to the ocean, where they could return to spawn again.

Range 

CCC Steelhead range from the Russian River to Aptos creek (Santa Cruz Co.) However, O. m. irideus ranges from coastal streams of Alaska to Baja

Habitat

  • Small cold water streams ranging from 15-18°C (can tolerate 20-23°C for short periods)
  • Few deep pools with overhead cover
  • Complex instream habitat like undercuts and large woody debris
  • Transitional gradient habitats
  • Gravel substrates free of excessive silts

Identifying Characteristics 

Juveniles

  • Round parr marks on side of body with excess spotting on back and dorsal fin
  • Spots in eye and on head and gill plate
  • Adipose fin has a dark edge


    steelhead parr

Adults

  • Ranges from very silver with light coloration on back with dorsal spotting to having a olive colored back and a pink to red lateral band.
  • Caudal fin is spotted on both lobes
  • White mouth, no black
  • Body appears more slender
  • 30-70cm in length


    Male steelhead in spawning phase

Fun Fact

  • Steelhead are iteroperous, meaning they reproduce more than once. Although only 10-20% of steelhead return to spawn more than once. Steelhead have been observed spawning up to 4 different times!
  • Steelhead can jump up to 11 feet and go from 0-25mph in 1 second

References and Recommended Readings