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Chum salmon, Oncorhynchus keta, are also sometimes known as dog or calico salmon.
They have the widest distribution worldwide of any of the Pacific salmon. The Yukon River in
Alaska and Canada produces the largest runs of chum salmon in North America.
Ocean stage chum salmon are metallic greenish-blue along the back with black speckles. They
closely resemble both sockeye and coho salmon at this stage. As chum salmon enter fresh water,
their color and appearance changes dramatically. Both sexes develop a "tiger stripe" pattern of
bold red and black stripes. Males develop a hooked snout and large teeth.
Chum salmon typically spawn in coastal rivers. Only the Yukon River in North America and the
Amur River in Russia have chum populations that are long-distance travelers. These fish can
migrate over two thousand miles to their spawning streams.
There are two life history forms of chum salmon in the Yukon River known as summer and fall chums.
Fall chums are larger, heavier fish, and tend to be older when they return to
spawn. Fall chums also enter the Yukon later and generally spawn farther up the river.
Chum salmon can return to spawn at between 3 and 6 years of age. Summer chum salmon enter
the Yukon on their spawning migrations from late May through mid-July. Fall chum salmon
enter the river from late June through early September. Summer chum salmon lay about 2,500
eggs, fall chum salmon lay over 3,300.
Chum salmon eggs in interior Alaska hatch while rivers and streams are still ice covered. Chum
salmon fry begin migration to the sea soon after emerging
from the gravel in the spring. Fry stay in river estuaries
for several months, then move into the open ocean in the fall and winter of their
first year. Most Alaskan chum salmon stay at sea for 2 to 5 years. As they near spawning age,
chum salmon start moving toward their home streams.
Until a few years ago, chum salmon were the least commercially important of the Pacific salmon.
Since then, a growing market has developed in Japan and Europe for fresh and frozen fish.
Over * 92,000 summer chum and 174,000 fall chum salmon were harvested from the Yukon River in 2006.
* Figures provided by ADF&G Special Publication No.07-01
Most chum salmon are caught with purse seines and
gill nets in the ocean. Fish wheels and gillnets are used
to catch fish swimming upriver.
Chum salmon have always been an important source of food for native people and their dogs in
over 200 rural villages in interior Alaska. Along the Yukon River, over * 84,000 summer chum
and 58,000 fall salmon
were caught by subsistence fishermen in 2003. These fish are caught with gill nets and fish
wheels and are smoked, dried, or frozen for winter subsistence use.
* Figures provided by ADF&G Alaska Subsistence Fisheries 2003 Annual Report
In the upper Yukon drainage, chum salmon select spawning sites in springs or groundwater
seepages to prevent the redds from freezing. Summer chums lay about
2,500 eggs, fall chums lay over 3,300. Chum salmon eggs in the Yukon River drainage hatch from
December to February while rivers and streams are still ice covered.
Low oxygen levels, water pollution, and predation by fish, insects and birds are all threats at this
stage. Excess sediment in the water is extremely dangerous as it can smother eggs or cover the
redd trapping fish inside.
A newly hatched salmon is called an alevin. At this stage, it looks like a thread with eyes
and an enormous yolk sack which provides all nutrition for the fish in the first weeks of its
As soon as the yolk sac is absorbed, chum salmon make their way up through the gravel and
immediately begin migration to the sea. In Alaska's interior, this migration often coincides with
the ice going out on the rivers.
Alevin require cold, clear, oxygen-rich water. Excessive sediment in the water is one of the
greatest dangers to salmon at this stage. It can reduce oxygen levels and cover the top of the
redd, trapping the fish inside. Aquatic insects and other fish are the primary predators.
Chum Salmon Fry
Chum salmon fry start their journey to the ocean soon after emerging
from the redd. Imagine a fish barely an inch long battling the current in the Yukon River! This
downstream migration can start with spring ice break-up on Interior rivers and continue into early
Chum fry form into schools once they reach the river estuaries. They
stay in shallow water for several weeks feeding on insect larvae and marine invertebrates, then move farther into the estuary. The fish move into the open
ocean by fall.
Chum Salmon Smolt
Many physical changes occur in a young salmon to help it make the transition from a freshwater
to saltwater existence. This process is called smolting.
The small fish replaces its parr marks, a pattern of vertical bars and spots useful for camouflaging the fry in
fresh water, with the dark back and light belly coloration used by fish living in open water. The
gills and kidneys change so that they can process salt water.
Smolting isn't as pronounced in chum salmon compared to other salmon species, since they have
such a short fresh-water residence period. The small fish can tolerate low salt concentrations
when they reach the estuary in the early spring. This tolerance grows rapidly until they are able to
move into the open ocean by fall.
Ocean Stage Adult
Most Alaskan chum salmon stay at sea for 2 to 5 years. During their ocean existence, their
primary diet consists of copepods, fish,
squid and tunicates.
Chum salmon from Interior rivers start moving into the open ocean in the fall and winter of their
first year. They leave the Bering Sea and swing south east through the Aleutian chain into the
Gulf of Alaska. During the following spring and summer, they travel north and west again. As
they near spawning age at 3 to 6 years, chum salmon start moving toward their spawning
Alaskan chum salmon can return to spawn at between 3 and 6 years of age. There are two distinct
spawning runs in the Yukon River known as summer and fall chums. Summer chum salmon
enter the river in late May or June with fall chum salmon following in late June or July. The fall
chum salmon are larger, fatter, and contain higher quality meat than the summer chum salmon.
Some fall chum salmon travel all the way up to the headwaters of the Yukon River in Teslin
Lake, 3,200 km from the river mouth.
Summer chum salmon lay about 2,500 eggs, fall chum salmon over 3,300. In the upper Yukon
drainage, chum salmon select spawning sites in springs or groundwater seepages to prevent the
redds (nests) from freezing during the winter months. Female fish rapidly pump their tails to
wash out a depression in the stream gravels. As she deposits her eggs, they are fertilized by the
male. The female salmon then uses the same tail movements to completely cover the eggs with
Text by USFWS staff
Graphics used by permission of Harry Heine
Last modified 24, February, 2009
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