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Tuesday, October 22, 2013

Why Salmon Jump.

October must be my favorite time to fish. After a long summer where the rivers dried up to a trickle the storms of autumn brought us a good rain that triggered one of the most dramatic animal migrations on planet earth, the return of the salmon. We are indeed fortunate to live in an area where the salmon have not been wiped out, yet. It is still possible to see the fish returning to the river which to some people is as exciting as catching them. 

The return of the salmon is a miracle of nature. The fact that these creatures can make the adjustment from salt to fresh water is an indication of just how tough they are. The salmon have survived a migration of thousands of miles through an ocean clogged with “Nylon Pollution,” that is over-fishing throughout the extent of their range. They return to their natal streams to find the mouths of these rivers packed with predatory marine mammals harbor seals and two kinds of sea lions the California and the Steller.

These protected species have become so over-populated they are adapting to fresh water. Harbor seals have been spotted up the Hoh, Bogachiel and Ozette Rivers. The effects on the salmon are obvious.       The fish are nervous and frightened of their own shadows. Salmon prefer to enter the river when the surf is high. The fish can hide in the turbulence and use their speed to get upstream and out of tidewater as fast as possible. This is hard on the fish because sometimes they have to enter the river several times in order to make the adjustment from salt water.  Very few of these fish make it out of the ocean and up the river without bite marks or chunks of flesh missing. Still the salmon come. You can see them jumping as they enter the river.

People have long wondered why salmon jump. Some say the salmon jump to rid themselves of sea lice which stick to the fish in salt water. I don't buy that. The sea lice will fall off the fish in fresh water anyway. So why do the salmon keep jumping when they have no lice?  Others say the salmon jump to loosen the eggs that they carry but I don't believe that one either.  Fresh salmon eggs are delicate. Why would the fish risk bruising them as they near the end of their spawning migration? And besides it is common to see spawned out salmon jumping in the river when they have no eggs inside. Another good theory is that the salmon jump to orient themselves to landforms and navigate their way back to the precise area that they were spawned. This is a good theory except for the fact that salmon don't always make it back to the same river where they spawned. Many get lost on their return journey and end up in the wrong river. That is how salmon repopulated their range after natural disasters like the ice age or a volcano. And if the salmon are navigating back to their streams by recognizing land forms, why would the spawned out salmon keep jumping?  They aren't going anywhere. A salmon, unlike a steelhead trout which can spawn many times, dies after it spawns.

No, I think the salmon jump for another reason entirely. There is in fact probably only one reason the salmon jump whether they are fresh from the ocean or drifting downstream tail first from the spawning bed. The salmon jump because they are happy.

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