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Did You Know...?
- …that all species of Pacific salmon hatch in fresh water, live much of their lives
in salt water and then return to fresh water to spawn and die?
- …that salmon can average 34 miles per day over long distances?
- …that each female salmon deposits 3,000 to 14,000 eggs in several gravel nests?
- …that only two to ten percent of the salmon's eggs survive to reproduce?
- …that salmon find their way to their home-waters by smell?
- …that salmon can smell one drop of "home" water (water from where
they were hatched) in 250 gallons of water from another source?
- …salmon's sense of smell is hundreds of times more acute than that of dogs?
- …that salmon, like other fish, have 300 degree vision?
- …that salmon can hear low frequency sound waves?
- …that salmon drift backwards when migrating to the ocean?
- …that young salmon must undergo many changes before they can
survive in the ocean?
- …that salmon change to bright colors when migrating up fresh-water streams?
- …that salmon can jump over waterfalls more than 12 feet high?
- …that some salmon travel for two months or more to reach their
spawning grounds without taking food?
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Against All Odds
Around the world, the changing seasons and an indefatigable
determination to survive impels many creatures of air, land and water to make an
all out do-and-die journey home to the place where they were born. It seems to be
part of the Creator's design for a myriad species of fish, animals, birds and even
insects. To observe the remarkable ability of these creatures to navigate, some
thousands of miles against incredible odds, is to think about the great Designer
who really is able.
Among such creatures the salmon is champion.
As with most creatures, there are various species of salmon.
Most popular is, perhaps, the king salmon. An Atlantic species, this salmon has tipped
the scale to as much as 126 pounds. But this is small compared to the fossil record of
one which claims a weight of about 500 pounds, a length of ten feet, and is even equipped
with fangs for battle. (How would you like a creature like this to swim up beside your boat?)
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Change
A salmon's life is one of change. Progressing from an egg,
to an "eyed egg," to an alevin, to a fry, and finally to a parr, the salmon is
finally ready to begin its incredible preparation for life in the ocean. Adapted
for life in fresh water, it would quickly die in the ocean. But the ocean is its
destination. Depending on the species, it begins migration to the ocean about a
year after hatching (chum and pink salmon begin their migration to the ocean no
more than a week or so after hatching!).
How will it survive when it gets to the ocean? Well, it won't—not
without the masterful handiwork of the Creator.
Before reaching the estuary (where fresh and salt water mix),
the fingerling undergoes a dramatic change called smolting. The fish become more
streamlined, their tails become more elongated and forked, the parr marks (vertical
bands on their sides) disappear and turn to a very silvery color. Simultaneously,
internal changes take place. The memory and smell centers in the brain grow rapidly.
(These are special features, as amazing as it may seem, that the Creator built into
the salmon for a special purpose which you will later see.) Also, the salmon's kidneys
convert to be able to excrete salt instead of retain it!
After reaching the estuary, the young salmon remain for a short
time while the final stages of smolting are completed.
Before it was a fresh-water fish which would quickly die in the ocean.
Now it is fully adapted for vigorous and competitive life in the deep salt water. But
its traveling days are far from over.
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Budding strength shines through a
ten-week-old salmon as it breaks free of its embryonic membrane. For
several more weeks it lives off its yolk sac, then rises to eat
microscopic plants and larvae. Turning silver two to four years later,
it heads downstream, developing a tolerance for salt water as it enters
the sea.
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Migration
Traveling in schools the Pacific salmon
migrate to the North Pacific Ocean where they remain for one to
seven years, depending on the species. For some, it is a long
journey of 3,000 to 3,500 miles—actually much further, because
salmon do not swim in a straight line. The Atlantic salmon
travel to Nova Scotia, Newfoundland, Labrador, and even to
East and West Greenland.
Salmon swim in the ocean an average of 18 miles per day and can maintain a
speed of 34 miles per day for long periods.
Salmon have a row of sensory pores called
lateral lines along their sides which help them navigate. The
sensory pores provide a means of hearing low frequencies which
help to detect very small ocean currents. They also help to find
food and avoid predators. Some Sockeye salmon also use the sun and
moon for navigation.
The Atlantic salmon spend different lengths
of time in the ocean before returning to their home-rivers for
spawning. Some spend one winter, others two, others three winters
in the ocean. Could the Master Designer have built in this feature
so all the eggs would not end up in one basket?
Incredible Journey Home
An instinct for procreation so strong that it
could only be by the Creator's design, the salmon changes course
and heads home.
How can they find their way to the place
where they themselves were given life? Remember the rapid
growth of memory and smell centers of the brain? Now they put
these features to good use. Salmon have a sense of smell hundreds
of times more acute than that of a dog. Scientific studies show
that they can detect one part per million, which is the equivalent
of one drop of their home waters in 250 gallons of water. The
Creator not only gave them this ability but also the ability to
recognize their home-waters by smell.
After traveling thousands of miles they finally
pick up the scent of their birthplace, whether a hatchery or a
stream, and they change direction once more. Then come the long,
seemingly impossible odds of navigating the rivers upstream.
Some of the chum and king salmon of the Pacific swim more than
2,000 miles up the Yukon River and its headwaters. Impelled by
a built-in desire to navigate to the site where they were
hatched, they fight rapids, and can leap falls more than 12
feet high! When they come to a fork in the river, they know
just which one to take—they remember!
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The Sockeye salmons' arduous
years-long journey leads from river to ocean and back to
river again. Young salmon (called parr) spend their first four
years in the fresh waters of the Alaska rivers, before
embarking on their "swimathon." Along the way they undergo a
major physical change (smolting) to be able to tolerate the salt
waters of the Bering Strait. Continuing their migration, they change
again as they return to the fresh waters of their home rivers
after years at sea, where they fight the current upstream to
their ancestral spawning grounds. Reaching "home port" they muster
the energy to spawn— and die.
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Endangered Life
The life cycle of the salmon is delicate.
The odds against survival from egg to the return to the spawning
grounds are very high. Only two to ten percent live to make the
journey.
From the time the eggs are deposited
beneath the gravel of a stream they must be provided with cold,
clean, swift water. Without the swift-movement of clean water the
incubating eggs will suffocate due to lack of oxygen. If the water
becomes too warm the salmon will become infested with disease. As
the climate becomes warmer, and due to deforestation, warming
water has become a concern. Many die from this cause alone,
and the threat grows every year.
Another threat to salmon is that of predators.
Fish and small animals are always ready to snatch a young salmon
during migration. Studies indicate that about 97% of Maine salmon
migrate at night to avoid predators as they swim backwards
downstream seeking the safety of deep areas. The Pacific king
and coho salmon are prized sports fish, and the Maine salmon,
now listed on the endangered species list, is also a favorite
sports fish for fishermen. While in the ocean they are fair
game for a variety of predators including seals, porpoises,
birds-of-prey, and other large fish. They swim in schools in the
ocean for protection, displaying their flashy silver sides to
confuse predators. Migrating back up the rivers many are met
with hungry bears anxiously awaiting their return.
Before beginning this long and difficult
journey, the salmon must be prepared. Why? While making this
amazing journey of two months or more and thousands of miles,
it is said that they never eat a bite of food! Their one purpose
is to reach home and spawn.
One Last Change
When in the salty waters of the ocean they
are a bright silver. But when making their way up the rivers other
changes takes place, varying according to the species and the inland
distance traveled.
The male Pacific salmon generally develop
hooked jaws, and their gills turn a bright red as they begin their
inland journey in fresh water. By the time they reach the spawning
grounds, some of the salmon are bright red, others green, brown,
striped, and even purple. These colors are most pronounced in males.
One species grows large canine teeth from which it gets its name,
dog salmon.
Spawning
The Pacific salmon's life ends with the
process called spawning. While the Pacific salmon spawns only
once and then dies, the Atlantic salmon may live to spawn three
or more times before dying.
Once salmon reach the spawning grounds,
the females choose a site and prepare nests (redds) for laying
eggs. They lie on one side and rapidly move their tails back and
forth over the gravel. Hardly touching the gravel with their tails
they create water currents that wash away the gravel. (Some of the
gravel can be as large as a fist!) These redds are about 6 inches
deep. This process takes up to a whole day. They then deposit from
500 to 1,200 eggs while the males fertilize them. After covering
the eggs, they move upstream, where the process is repeated for as
many as four more times, until a total of 2,500 to 6,000 eggs have
been deposited per salmon, depending on the species. Why so many
eggs? The Creator has made this provision for the benefit of many
creatures, not the least of which is man. By the time the females
have finished spawning, they have lost half their weight.
Through dogged determination, strength and
navigational abilities that only an intelligent Creator could
provide, they have accomplished their mission. With what strength
is left, the adult Pacific salmon guard the site until their death
as an instinctive loyal duty dictates. Interestingly, the decaying
bodies of these fish form a plentiful food supply for small
organisms which are the main food source for the hatching offspring.
Sources
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