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Juvenile Chum ID
During their first year of life, young salmon can often be difficult
to identify, particularly after they lose their parr marks. The following
simple guide to juvenile salmon identification, is from The Stream
Scene - Watersheds, Wildlife and People (1990), by Oregon Department
of Fish and Wildlife, Portland, Oregon. For more definitive identification
information, two more comprehensive field guides are listed below.
Additional Reading
Field Identification of Coastal Juvenile Salmonids (1997), by
Pollard, Hartman, Groot, and Edgell. Harbor Publishing, Madeira Park,
BC Canada.
Key to field identification of anadromous juvenile salmonids in the
Pacific Northwest (1972), by McConnell and Snyder. U.S. Government
Printing Office, Washington D.C.
Adult Chum ID
Maturing chum salmon return to Washington waters in the typical silvery
ocean coloration. As the fish near their spawning streams, they begin
to undergo changes in both color and physical form. The color gradually
changes from silver with a dark back, to spawning colors dominated by
an irregular pattern of bars on their sides.
Ocean Phase
Ocean coloration, sexes similar. |
- Typical Coloration - Silvery sides with a green
or blue back and white tips on the ventral and anal fins. Some black
speckling may be present, and faint indications of a vertical bar pattern
may be visible.
- Distinguishing characteristics - Identified by the
absence of large black spots on the body or fins, the slender caudal
peduncle, and large scales.
Spawning Phase
Male chum salmon in spawning
colors |
Femle chum salmon in spawning
colors |
- Typical Coloration - Body color typically olive or
gray with maroon and black vertical bars. Actively spawning females
and subdominant males can display a horizontal black stripe in place
of the bar pattern. The striped pattern is a signal to other fish that
is used to reduce aggression.
- Distinguishing characteristics - Identified by the
vertical pattern of bars along the sides, dark or black ventral surfaces,
and white tips on the ventral and anal fins.
Live female chum spawner showing
the striped pattern |
Subdominant male chum spawner
also displaying a striped pattern |
Sexing Chum Spawners
The identification of male and female chum salmon can be difficult when
the fish are in marine waters and have not yet begun to develop the sexual
characteristics associated with maturation and spawning. Chum spawners,
however, are easily sexed and the following guide illustrates the different
male and female characteristics.
- Body Shape
Male chum spawners are deeper bodied than females,
and have flat sides with hollow bellies. The females retain the more
slender body shape of the ocean fish and will display a rounded belly
when distended with eggs (see photograph below).
Male (top) and female (bottom)
chum salmon in spawning colors |
- Head and Jaws
The size and shape of the head and jaws are the most obvious characters
that show differences between male and female chum spawners. The males
display large heads with massive, elongated jaws, hooked snouts, and
characteristic dog-like teeth. The head of the female chum changes
only slightly from the ocean form, with a slight elongation of the
jaws and development of more modest spawner teeth.
Male chum spawner showing
strongly developed jaws and teeth |
Female chum spawner with
more modest head and jaw development |
- Adipose Fins
An often over-looked sexual characteristic in Pacific salmon is the
enlarged adipose fin on mature males, typically 2-3 time larger than
on female fish.
Close-up of enlarged male
adipose fin |
The female adipose fin retains
its pre-spawning size and shape |
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Identifying Chum Salmon
