Chinook Salmon

Introduction: Chinook or King Salmon are the largest of the Pacific Salmon and can attain weights in excess of 100 pounds, with the largest confirmed fish weighing in at 127lbs. Most adult fish are much smaller than this though, and the average size is between 10 and 25 pounds and 28" and 40" in length (Behnke 2002). Due to their size, life history patterns and somewhat due to over-harvest Chinook are also the least abundant species of Pacific salmon.

Life History Information: For the most part Chinook spawning runs usually begin prior to coho runs, and in western Washington fall runs occur between the end of August and October. However the spring runs arrive much earlier and summer runs are usually between the two others. These differences run timings are largely due to the habitat that is used by the spring and fall run fish. Spring Chinook tend to rear near the headwaters of streams in areas that are often not accessible except during high flows of spring. Due to this their runs often occur between April and June. The fall Chinook on the other hand tend to use the lower reach of rivers as spawning and rearing habitat, allowing them arrive during lower flow periods. One river of note is the Sacramento which has four distinct spawning runs of Chinook salmon; winter, spring, summer and fall. As a generally rule, Chinook salmon are fall spawners, but the winter run fish from the Sacramento River generally arrive in January and February, and represent the only native population of Chinook known to spawn during the spring (Behnke 2002). Once the Chinook reach the inner estuary of their spawning stream they stop feeding, which is believed to occur to allow room for their eggs or sperm to develop. Some populations of Chinook spawn very far from the ocean, and have been noted to spawn between 1000 and 2000 river miles upstream of the mouth of the river. Generally speaking Chinook salmon spawn in larger streams and rivers and unlike other species of salmon with often spawn in the main stem of the stream.
Most juvenile Chinook migrate to the ocean at between one and three years of age, although in the southern part of their range one year is more common. Once the smolts enter the saltwater, they often spend a while feeding in the estuaries (generally in the spring). While some Chinook salmon remain in estuarine waters near their home river most travel further out to sea. The general trend for Chinook salmon is to travel northward from their home stream while remaining in coastal waters (Quinn 2005). This is just a general trend though, and catch records from fishing on the high seas indicate that a large number of Chinook salmon do travel out to offshore waters. In the Puget Sound, "blackmouth" are known as the estuarine life history form that matures in the waters of the sound instead of traveling further out to sea. Chinook in the saltwater show a low tolerance to light, and are generally found in deeper water than the other four species of salmon. In the ocean their diet is largely made up of other fish (60 - 70%) but they also feed on crustaceans, which make up the remaining 30 - 40% of their diet. Most Chinook return to spawn at two to five years of age, with some returning at up to eight years old.
Genetically speaking, both Chinook and Coho are more closely related to trout than other North American species of salmon. Chinook salmon also have a stream resident life history pattern where the parr (juvenile fish) stay in the stream until adulthood. While Chinook have never been documented to survive to spawn more than once in the wild, under hatchery conditions resident male Chinook parr have been show to have the ability to spawn up to three times (Unwin et al. 1999). Although hybridization with other species of salmon is rare, Chinook have been documented to hybridize with both Coho and Pink salmon most likely due to hatchery stock influences.

Status: Currently Chinook populations are depressed throughout much of their native range. Of the 17 recognized evolutionarily significant units (genetically distinct populations) of Chinook salmon in Washington, Oregon, Idaho and California, two are listed as endangered, and seven are listed as threatened (NOAA, 2007). The causes for the decline of Chinook salmon can be traced back mainly to the four H's. In the Columbia River system, hydroelectric dams have severally limited the abundance of Chinook salmon. The Grand Coulee dam alone in eastern Washington, which was built without a fish ladder cut off access to over 1,000 miles of spawning and rearing habitat. To reach the uppermost spawning grounds in the Columbia River system, Chinook must travel over nine dams. A study done on hatchery Chinook smolts in the Snake and Columbia River systems showed that there is about a 6% to 11% mortality rate at each dam (Muir et al. 2001). Some of the causes of this mortality include damage from contact with the turbines, delayed migration timing due to the slack water behind the dams, and increased predation. When you add in the damaged done to Chinook populations by habitat destruction, hatchery fish, and over harvest, it is easy to see why so many populations are in trouble.

Description: Chinook Salmon have very irregular shaped and sized black spots, which are found above the lateral line, and across their dorsal and caudal (tail) fins. In juvenile Chinook salmon in freshwater, tend to display a Chinook tend to have olive to greenish-brown backs and silvery sides. Like all species of Pacific Salmon, Chinook are bright silver colored while in the salt water. A distinguishing feature between Chinook and coho salmon is that Chinook have a black coloration on their gums gaining them the name "blackmouth" while Coho have more of a gray to white color on their gums. When they reach the freshwater to spawn, Chinook develop a reddish brown to maroon color on their sides and males develop a kype.

Fly Fishing Information: Although Chinook can be readily taken on the fly under the right conditions, they are not considered to be nearly as fly friendly as Coho, Pink or Chum Salmon. Since Chinook are very sensitive to light, they tend to hold in very deep water while at sea, far from shore thus being out of the range of beach anglers most of the time. However for those anglers to don't mind missing some sleep, Chinook can found near shore during low light conditions and will often aggressively attack flies. In rivers they like to hold in deep pools and are best targeted will sink tip lines and large flies, but can be quite "lock-jawed" at times.