The chum salmon ( Oncorhynchus keta), also known as dog salmon or keta salmon,
In Japan, chum salmon is also known as the shiro sake, aki sake or simply sa ke, while historically it was known in kun'yomi as sa ke up until the Meiji period.
Description
The body of the chum salmon is deeper than most salmonid species. In common with other species found in the Pacific, the anal fin has 12 to 20 rays, compared with a maximum of 12 in European species. Chum have an ocean coloration of silvery blue green with some indistinct spotting in a darker shade, and a rather paler belly. When they move into fresh water the color changes to dark olive green and the belly color deepens. When adults are near
spawning, they have purple blotchy streaks near the
caudal peduncle, darker towards the tail. Spawning males typically grow an elongated snout or
kype, their lower fins become tipped with white and they have enlarged teeth.
Some researchers speculate these characteristics are used to compete for mates.
Sizes
Adult chum salmon usually weigh from with an average length of . The
fishing tackle world record for chum recognized by the IGFA is and caught by Todd Johansson on July 11, 1995 at Edye Pass (a channel between Prescott and
in the
Hecate Strait) in the North Coast region of
British Columbia;
while the all-tackle length world record is caught by Vicki D. Martin on October 20, 2021 at
Wynoochee River in Washington.
Life cycle
Chum live for an average of three to five years, and chum in Alaska mature at the age of five years.
Spawning
Most chum salmon spawn in small streams and
. Some chum travel more than up the
Yukon River. Chum
fry migrate out to sea from March through July, almost immediately after becoming
free swimmers. They spend one to three years traveling very long distances in the ocean. These are the last salmon to spawn (November to January) in some regions. In Alaska they are the first to spawn in June and August and are then followed by
pink salmon and
coho salmon. They die about two weeks after they return to the freshwater to spawn. They utilize the lower tributaries of the watershed, tend to build nests called
redds, really little more than protected depressions in the gravel, in shallow edges of the watercourse and at the tail end of deep pools. The female lays eggs in the redd, the male sprays milt on the eggs, and the female covers the eggs with gravel. The female can lay up to 4000 eggs.
Diet
Juvenile chum eat
zooplankton and
insects. Recent studies show that they also eat
comb jelly. As adults, they eat smaller fish.
Distribution
Chum salmon have the largest
natural range of any Pacific salmon. Chum are found all around the
North Pacific, off the coasts of
Japan,
Korea, the Russian Far East,
British Columbia in
Canada, and from
Alaska to
California in the
United States. They undergo the longest migrations within the genus
Oncorhynchus, far up the
Yukon River in
Alaska and Canada, and deep into the
Amur River basin in
Northeast China and
Russia. In lesser numbers they migrate thousands of kilometers up the
Mackenzie River. In the
Arctic Ocean they are found in limited numbers from the
Laptev Sea to the
Beaufort Sea.
In
North America chum salmon spawn from the Mackenzie River in the
Arctic to as far south as the
Umpqua River,
Oregon, although they were also reported in the San Lorenzo River near Santa Cruz, California in 1915
and the
Sacramento River in northern California in the 1950s.
In fall 2017 a half dozen chum salmon were counted in
Lagunitas Creek about north of San Francisco, California.
In the open ocean, chum salmon stay fairly high on the water column, rarely diving below . Their typical swimming depths are from the surface during the day, and during the night.
Commercial use and value
The registered total harvest of the chum salmon in the North Pacific in 2010 was some 313,000 tons, corresponding to 91 million fish. Half of the catch was from
Japan, and about a quarter each from Russia and the United States. In 2010, the chum salmon harvest was about 34% of the total harvest of all
Pacific salmon species by weight.
The chum salmon is the least commercially valuable salmon in North America. Despite being extremely plentiful in Alaska, commercial fishers and sport anglers often choose not to target them because of low market value due to the fact that the chum salmon is the least desirable salmon for human consumption. Recent market developments have increased the demand for chum salmon, due to new markets developed from 1984 to 1994 in Japan and Northern Europe. They are a traditional source of dried fish.
Conservation
Two populations of chum salmon have been listed under the Endangered Species Act as threatened species. These are the
Hood Canal Summer Run population and the Lower
Columbia River population.
Susceptibility to diseases
Chum are thought to be fairly resistant to
whirling disease, but it is unclear.
Notes
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