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Chum Salmon
Chum salmon
(Oncorhynchus keta) have the widest distribution of any of the Pacific
salmon. They range south to the Sacramento River in California and the island of
Kyushu in the Sea of Japan. In the north they range east in the Arctic Ocean to
the Mackenzie River in Canada and west to the Lena River in Siberia. Chum salmon
are the most abundant commercially harvested salmon species in arctic,
northwestern, and Interior Alaska, but are of relatively less importance in
other areas of the state. There they are known locally as "dog salmon" and are a
traditional source of dried fish for winter use.
General description: Ocean fresh chum salmon are metallic
greenish-blue on the dorsal surface (top) with fine black speckles. They are
difficult to distinguish from sockeye and coho salmon without examining their
gills or caudal fin scale patterns. Chum have fewer but larger gillrakers than
other salmon. After nearing fresh water, however, the chum salmon changes
color-particularly noticeable are vertical bars of green and purple, which give
them the common name, calico salmon. The males develop the typical hooked snout
of Pacific salmon and very large teeth which partially account for their other
name of dog salmon. The females have a dark horizontal band along the lateral
line; their green and purple vertical bars are not so obvious.
Life history: Chum salmon often spawn in small side channels and other
areas of large rivers where upwelling springs provide excellent conditions for
egg survival. They also spawn in many of the same places as do pink salmon,
i.e., small streams and intertidal zones. Some chum in the Yukon River travel
over 2,000 miles to spawn in the Yukon Territory. These have the brightest color
and possess the highest oil content of any chum salmon when they begin their
upstream journey. Chum salmon spawning is typical of Pacific salmon with the
eggs deposited in redds located primarily in upwelling spring areas of streams.
Female chum may lay as many as 4,000 eggs, but fecundity typically ranges
between 2,400 and 3,100 eggs.
Chum do not have a period of freshwater residence after emergence of the fry
as do chinook, coho, and sockeye salmon. Chums are similar to pink salmon in
this respect, except that chum fry do not move out into the ocean in the spring
as quickly as pink fry. Chum fry feed on small insects in the stream and estuary
before forming into schools in salt water where their diet usually consists of
zooplankton. By fall they move out into the Bering Sea and Gulf of Alaska where
they spend one or more of the winters of their 3- to 6-year lives. In
southeastern Alaska most chum salmon mature at 4 years of age, although there is
considerable variation in age at maturity between streams. There is also a
higher percentage of chums in the northern areas of the state. Chum vary in size
from 4 to over 30 pounds, but usually range from 7 to 18 pounds, with females
usually smaller than males.
Noncommercial fishery: In arctic, northwestern and Interior Alaska,
chum salmon remain an important year-round source of fresh and dried fish for
subsistence and personal use purposes. Sport fishers generally capture chum
salmon incidental to fishing for other Pacific salmon in either fresh or salt
water. Statewide sport harvest usually totals fewer than 25,000 chums. After
entering fresh water, chums are most often prepared as a smoked product.
Commercial fishery: In the last few years an average of 11 million
chum salmon, worth over $32 million, have been caught in Alaska. Most chum are
caught by purse seines and drift gillnets, but fishwheels and set gillnets
harvest a portion of the catch. In many areas they have been harvested
incidental to the catch of pink salmon. The development of markets for fresh and
frozen chum in Japan and northern Europe has increased their demand, especially
in the last decade. The Alaska Department of Fish and Game has built several
hatcheries primarily for chum salmon products.
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