Chinook salmon are easily the largest of any salmon with adults typically exceeding 40 pounds. Chinook mature at about 36 inches and 30 pounds. Chinook salmon have blue-green back with silver flanks while at sea with small black spots on both lobes of the tail and black pigment along the base of the teeth.
Adults migrate from a marine environment into the freshwater streams and the rivers of their birth in order to mate. They spawn only once and then die. Juvenile Chinook may spend from 3 months to 2 years in freshwater before migrating to the ocean to feed and mature. Chinook salmon remain at sea for 1 to 6 years (more commonly 2 to 4 years), with the exception of a small proportion of yearling males (called jack salmon) which mature in freshwater or return after 2 or 3 months in salt water.
There are different seasonal “runs” in the migration of Chinook salmon from the ocean to freshwater, even within a single river system. These runs have been identified on the basis of when adult Chinook salmon enter freshwater to begin their spawning migration. Freshwater entry and spawning timing are believed to be related to local temperature and water flow regimes.
When salmon reach their final destination, they deposit their eggs at a time to ensure that young salmon fry emerge during the following spring when the river or estuary productivity is sufficient for juvenile survival and growth. As Chinook salmon seek deeper water, their gills and kidneys begin to change so that they can process salt water.
Two distinct types or races among Chinook salmon exist: a “stream-type” Chinook, found most commonly in headwater streams of large river systems, and an “ocean-type” Chinook, commonly found in coastal streams in North America.
- – The above information is from the National Oceanic and Atmospheric Administration website.