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The pink salmon, Oncorhynchus gorbuscha,is the smallest and most abundant of the
Pacific salmon. It also has the shortest lifespan of all the Pacific salmon, and spends
the least amount of time in fresh water. Pink salmon can reach a length of 30 inches and a
weight of up to 14 pounds, but a body weight between 2 – 7 pounds is more typical.
In the ocean, pink salmon have steel blue to blue-green backs,silver sides, and a white belly.
Large, oval, black spots cover the back, adipose fin
and both lobes of the tail. Spawning fish have dark backs with a pinkish wash and green blotches
on their sides. Males develop a strongly hooked snout and sharp teeth, and an enormous hump behind the head.
This gives the fish its other common name, “humpback salmon”, or “humpy”.
Range And Abundance
The range of the pink salmon extends from La Jolla, California north to the Arctic Ocean,
east to the Mackenzie River Delta, and west across Siberia to the Lena River. In the western
Pacific Ocean, pink salmon can be found as far south as Korea and Kyushu, Japan.
Pink salmon may spawn anytime from June to late September depending on location and distance
from salt water. Most populations spawn in coastal streams, but some pinks travel over 136
miles up the Yukon and Kuskokwim Rivers. The female prepares a
redd and deposits between 800 – 2,000 eggs that are fertilized by the male. The young hatch
out from late December through February. Fry emerge from
the gravel in April or early May and almost immediately begin moving downstream to the sea.
Smolts spend the first month in estuaries, then move farther offshore. Adult Alaskan pink salmon range from
the Bering Sea, out the Aleutian chain, and as far south as the California coast. Adults spend
18 months in the ocean then return to spawn completing their life cycle in just two years.
Due to the two year life cycle, the pink salmon runs in odd and even numbered years are
genetically separate. These distinct populations can look slightly different and have
much different run sizes.
Millions of pounds of pink salmon are caught annually, but the quality of the fish is
low, resulting in a low price paid to fishermen. Almost all of the pink salmon caught
is canned. There is also a small coastal sport fishery for pink salmon.
Pink salmon are mainly used as food by Alaska Natives living along the coast. They are
caught in gill nets and beach seines and dried or
The number of eggs produced by a female pink salmon can range from 800 to over 2,000
depending on the size of the fish. The eggs are deposited in a series of gravel nests,
called redds. The female makes a redd by swishing her tail in the water to move sediment
and fine gravel and create a depression in the stream bed.
Up to 85% of the eggs can be lost before hatching. Low oxygen levels, freezing, water
pollution, and predation by fish, insects and birds are all threats at this stage.
Excess sediment in the water is also extremely detrimental 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 has a yolk sack which provides all nutrition
for the fish through the winter. Pink salmon alevin remain in the redd
until the yolk sac is absorbed. This occurs between April and early June.
At this point, they work their way up through the gravel and become free-
swimming, feeding fry.
Alevin must have cold, clear, oxygen-rich water to remain healthy. Excessive
sediment in the water is one of the greatest dangers to salmon at this stage.
It can smother newly-hatched fish or cover the top of the redd, trapping the
alevins inside. Aquatic insects and other fish are the primary predators of
Pink salmon fry begin to move downstream to the sea almost as soon as they emerge
from the gravel. The tiny fish hide in stream gravels during the
day and travel at night. This journey may only take a day for fish that hatched in
coastal streams. Fry stay in coastal estuaries
for about a month before beginning to move offshore. Many fry are taken by birds,
fish and other animals during this period.
Many physical changes occur in a young salmon to help it make the transition from a freshwater
to saltwater existence. One of the primary changes occurs in the gills and kidneys as they
change so that they can process salt water.
The young fish remain in estuaries and tidal creeks for several months feeding on
plankton and larval
tunicates. They gradually move into deeper, saltier water, but remain near shore.
Ocean Stage Adult
Pink salmon spend 18 months in salt water. As they grow larger, their diet begins to include
small fish as well as various types of plankton. Adult Alaskan pink salmon can be found in most
of the northeast Pacific ranging from the Bering Sea, out the Aleutian chain, and as far south
as the California coast.
Pink salmon reach sexual maturity at 2 years of age. They begin to return to spawn anytime from
June to late September depending on the location and distance from salt water. Pink salmon have a
weaker homing instinct than other salmon species and often stray far from their natal stream to spawn.
The male salmon guards the female from other males while the she rapidly pumps her tail to wash out a
depression in the stream gravels. As she deposits her eggs, they are fertilized by the male. The female
salmon then moves directly upstream and uses the same tail movements to dig again and cover the eggs.
Text by USFWS staff
Graphics used by permisssion of Harry Heine
Last modified 3 March, 2009
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