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Creation 18(3):26–28, June 1996

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Pacific salmon

The ocean’s high achievers

by Denis Dreves

One of the great resources of the west coast of the United States and Canada is the multitude of salmon in the coastal ocean and rivers.

Pacific salmon life-cycle: The female returns to her spawning area and releases her eggs into a scooped-out depression. In spring the eggs produce alevins, which have yolk sacs below their bellies which contain all the nutrients they need for proper growth. Then the fry emerge and migrate to saltwater, where in the following spring they migrate to the sea for 2 1/2 years. As adults, the salmon complete their life-cycle when they return home to spawn. Click for larger view.

The life cycle and habits of salmon have been studied in detail because of the fish's usefulness as a food resource — not only for the people of this region, but also as a major export.

The building of dams on many of the rivers where salmon return to spawn has made it necessary to invent ways to divert returning fish into artificial hatcheries or to create man-made channels where the fish can return to spawn as naturally as possible. Both methods have proved effective in enhancing the salmon industry and preserving many salmon runs which would otherwise have been destroyed.

Salmon begin their remarkable life-cycle from eggs which have been laid, fertilized, and covered with gravel (sometimes sand) in the upper reaches of a river or stream. Water must flow through the gravel to supply oxygen.

After incubation, tiny alevins (pronounced AL-i-vinz) emerge from the eggs. Alevins have a yolk sac below their bellies which contains sufficient nutrition for their early development. They do not emerge from under the gravel during this alevin stage, but stay there for protection against predators until their yolk sac is fully absorbed.

When they emerge they are 3-4 centimetres (about 1 1/2 inches) long, and are called fry. They make their way to larger freshwater pools for protection from sunlight and predators. The time which fry stay in fresh water varies with the species, and can be from two to 20 months.

Adapting to salt water from fresh

Partly incubated salmon eggs in a hatchery.
Partly incubated salmon eggs in a hatchery.

Salmon alevins
Salmon alevins.

Just before they journey downstream to the ocean, some physiological changes occur, and the young salmon are now called smolts. Here an amazing adaptation takes place: the creatures start to adapt from their freshwater homes to the salt water of the ocean. This process will be reversed again when the fish later return to the place of their birth to spawn. After a period of adjustment to salt water at the river's mouth, they make their way to the sea, where they spend most of their adult lives.

Time spent in the ocean also varies with species, but is normally one to five years. While in the ocean, salmon travel thousands of miles from their native rivers. The mystery of migration is still only vaguely understood, and is another of the many evidence of intricate design found in created things.

There is evidence to support the conclusion that salmon have a number of senses which lead them back to their native stream to spawn. These include the earth's magnetic field, position of the sun — and possibly the moon and stars — along with the ability to detect the chemical composition of the stream from which they began. Each stream and river has minor differences in chemical composition, and there is good evidence to conclude that salmon taste the difference to identify their native stream. This method, of course, would only be useful once they have already located the general area using their other senses.

When they arrive at the mouth of their native river to spawn, Pacific salmon spend time adjusting back to fresh water. Amazing physiological changes again take place in preparation for spawning, and the internal organs of the fish also begin to deteriorate.

Autumn rains trigger journey home

Dmitry Azovtsev, wikimedia commonsBearFishingSalmon
The spawning salmon also provide bears with a food source.

The exact time salmon begin their extraordinary return upstream to their spawning grounds varies, but actual spawning takes place in autumn. They make their way upstream, usually when autumn rains come and raise the stream levels. They jump obstacles, negotiate rapids, and sometimes stop to rest in larger pools where water is moving more slowly. They eventually reach the gravel beds at the top of the stream where they began their lives.

After surviving the gruelling journey back to the place they were born, the fish select a mate and begin the spawning process in a riffle (shallow water almost filled with gravel where water is forced to flow through). The female vigorously sweeps her tail in the gravel and digs a hollow called a redd. Then both male and female face upstream. The female lays a batch of eggs and simultaneously the male at her side releases a cloud of milt to fertilize them. The female then covers the eggs with gravel, and they repeat the process several times. Thousands of eggs are laid. Shortly after completing spawning both male and female die.

(Though it is true that Pacific salmon species all die immediately after the first time they spawn, Atlantic salmon do not. Atlantic salmon may go back to sea and return to spawn up to four times.)

Job 12:8 and 9 tells us to “Speak to the earth, and it shall teach thee: and the fishes of the sea shall declare unto thee. Who knoweth not in all these that the hand of the Lord hath wrought this?

The salmon's remarkable achievements and life-style, particularly in its amazing ability to navigate great distances with perfect accuracy against incredible odds, are impossible to explain satisfactorily as a result of purposeless, unguided evolution. Instead, the Pacific salmon can be seen to be a wonderful testimony which clearly points us to the Creator.

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Readers’ comments

Willem D.
This makes me wonder how salmons managed to survive The Flood. They must have been unable to find their birth stream, because the whole surface of the Earth was reshaped; their birthstream was no longer there. Any thoughts on that? Could it be that the salmons of Noah's day were not as choosy as today's salmons? Or are there better explanations?

(There was a time such questions could shake my faith to the ground, because maybe the Bible wasn't true after all. Thank God those days are over!)
Don Batten
This raises the question of animal migrations in general: whales, sea turtles, many kinds of birds, butterflies (e.g. the monarch). Some of the birds have similar precision to the Pacific salmon. This article discusses bird migration in some detail, including ideas about how such patterns came about. In short, we can only speculate. It's really a mystery to everyone.
It could be that a traumatic cataclysm like the Flood could reset an animal's migratory apparatus and then the survivors would need to find a stream to spawn in ('sniffing' out fresh water flowing into the ocean) and thus imprint this pattern on their offspring (there is growing evidence for environmental factors imprinting the genetics of following generations, such as with human obesity for example).
Chris C.
As a former fisheries professional, the one issue I would take with this article is the assertion that hatcheries and artificial spawning channels "both ... have proved effective in enhancing the salmon industry and preserving many salmon runs which would otherwise have been destroyed." This statement is misleading on several points. The first concerns the use of the word "enhancing." In fisheries parlance, this word has a particular meaning and refers to the propagation of fish over and above what is naturally produced by the fishery being enhanced. Most salmon hatcheries are not enhancement hatcheries. Rather, they are referred to as mitigation hatcheries. Mitigation is intended to produce fish to replace those that are lost due to detrimental human activities such as dam building. In the case of dams, mitigation hatcheries are intended to replace the production capacity of upstream habitat when that habitat is no longer accessible to migrating fish.

The second problem is the assertion that hatcheries and spawning channels are "effective" at preserving fish stocks. There is little evidence that such is in fact the case. In virtually every West Coast system that has been dammed, salmon numbers continue to remain at levels far below historic averages, and many stocks are at high risk of extinction, in spite of decades now of hatchery production.

The real problem is that due to their migratory nature and specific life history needs, salmon numbers are affected by a wide range of environmental factors, making it extremely difficult to assess the effectiveness of artificial propagation in isolation. Salmon fisheries management is a tricky dominion problem that truly tests our abilities to both steward the resource and serve the needs of people.

Very respectfully,
Don Batten
I think the author used the word 'enhancement' in the sense of lifting the populations above what they would have been if the mitigation strategies had not been applied.
Thanks for your clarificaiton.
Bud B.
It occurred to me while reading the article about the intricacies of the life cycle of the Salmon, that you are preaching to the choir (so to speak). Those of us who are convinced that the universe is young, will read your article and nod and say to themselves "of course" but I was speaking to a member of my church yesterday about a young earth and was unable to get past the wall of his faith in an old universe. He smiled at the examples I shared and said, "isn't it amazing how nature has evolved such complex systems over billions of years?" Can you point me toward articles CMI's massive library that might break through that complacent blindness of my friend?
Don Batten
To dent his confidence in the evolutionary story, I suggest the documentary and book, Evolution's Achilles' Heels.
However, he needs also to face up to the consequences for the Gospel of his belief in long ages of death, disease and suffering before Adam. I recommend our new video, Is Creation a Secondary Issue? (No, it's all about Jesus). It is available as DVD or a video download. A short article that covers some of these issues is Some questions for theistic evolutionists or the more comprehensive: Did God create over billions of years? And why is it important? And there are many other relevant articles on the Creation: Why it matters Q&A page.

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