Home About the Watershed

Salmonid Species

As anadromous fish, salmon form the Mattole watershed spend the first portion of their life in freshwater streams and rivers.  Undergoing a process of known as smolting, the salmon venture out into the ocean and transition into life in salt water.  The salmon complete their life cycle as spawning adults by returning to their native streams.  Home to three genetically unique salmon species, the Mattole River is one of the most important habitat zones in Northern California for endangered native salmon.

Fun Fact: One pair of spawning salmon can produce 3000-5000 eggs inside a single redd, and only a few of those will return to spawn as adults.

Salmon Species Description

Chinook (Oncorhynchus tshawytscha): The largest of any salmon species (weighing up to 60lb), chinook quickly migrate downstream after emerging as fry.  After spending several months in the river, chinook will reside in the estuary for several weeks to complete smoltification.  Migrating out into the ocean, the salmon will spend two to four years feeding in offshore and coastal waters.  Distinguishing characteristics of chinook are completely black gum lines and peanut shaped spotting on the on the top half of their bodies.  Mattole chinook are fall run returning to their streams from October through November.

Coho (Oncorhynchus kisutch): Fry are colorful with orange dorsal and anal fins with black edges.  Typically, juveniles spend one to two years in streams and smolt in the ocean.  Adult coho return to their streams in the fall and winter after spending two summers feeding in coastal waters.  Adult coho are characterized by distinctly white nostrils and a jaw with white gums and a black mouth.  Generally, mature fish also have red along the body and spots on the upper lobe of the tail.

Steelhead (Oncorhynchus mykiss): Fry are characterized by spots on the dorsal and adipose fin.  Juveniles typically spend one to three years in their streams and later reside in the ocean for another one to three years.  Seawater adult steelhead have square tails and numerous small black spots along their bodies.  The steelhead have a winter and summer run and return to the Mattole between January-February and March-June.  The most adaptable of the three salmon species, the steelhead are generally successful at surviving the changing environmental conditions in the Mattole watershed.

Fun Fact: A steelhead is the same species as a rainbow trout.  However, while some rainbow trout stay in their home stream their whole lives, others venture into the ocean and return with a silvery color…”steelhead”, get it?  Steelhead can make many trips to and from the ocean, while Chinook and coho salmon return only once to spawn, and then die.

Salmon Population Status

An often quoted phrase describing the historical abundance of salmon species in the Mattole watershed is, "you could walk across the river on the backs of salmon."  Today, all three of the native three salmon species-Chinook, coho, and steelhead-are listed as threatened under the Federal Endangered Species Act.  Coho populations are extremely low and are further listed under the California State's Endangered Species List.





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