20 Days of Chill - Swimming Upstream

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Welcome back to 20 Days of Chill, today's topic is "swim upstream" which made me immediately think of wild salmon in Alaska.

Fish like salmon are born in freshwater streams and rivers, and live their adult lives in the ocean.

After spending 2-7 years in saltwater they are mature and ready for the final and most difficult journey of their lives. 

In the fall, mature salmon return from the ocean to the stream of their birth to lay eggs in the same spot where they were born. 

To accomplish this, they must swim upstream against the current or flow of the stream. They typically travel hundreds, if not thousands of miles, at a speed of 18 miles a day - just imagine! Swimming upstream!

How do they know where to go? 

Scientists believe salmon use a combination of a magnetic and celestial orientation and the memory of their home stream's unique smell - obviously salmon can detect one drop of water from its home stream mixed up in 250 gallons of sea water. 

In the course of this journey they eat nothing, using the energy they stored while they were in the ocean. Finally, those who survive, reach the river where they were born years earlier.

Salmon are all bright silver while in the ocean environment, however when the they return to freshwater to spawn, they undergo many physiological and morphological changes. First they must switch from using saltwater to freshwater. Returning to freshwater, they change body color from a silver to a brown, green or red depending on the species, Sockeye, Chum, Pink, Coho or Chinook being the most popular ones.

The female digs a hole in the gravel with her tail and lays a few thousand eggs in the hole that will be fertilised by the male fish. Eventually, after 12 - 20 weeks, an average of three new baby salmon hatch out of these eggs.

There are some dangerous obstacles that often interrupt / terminate the salmon’s return home, aka salmon run: 

Predators waiting for their lunch!

And can you blame the bears (or eagles, sea lions, whales and sharks, and let's not forget humans)? 

I mean most people like salmon. Because Sushi. 

Especially when they have been made by this adorable junior sushi chef. My son Colin got a kids' sushi making class the weekend before Christmas, and he did a great job!

Salmon rainbow rolls are my favorite.

PS: I read that a lot of fish swim against the flow even when not migrating. They face the current by using their streamlined body and powerful tail to keep themselves in one place. This is how they catch food like insects and worms without having to swim around and chase it. 

PPS: I didn't know this, but after spawning most salmon die. Even though while living in the ocean  they're building up fat reserves, they put so much energy into swimming upstream, remember, 18 miles every day, hurling themselves agains the downward flowing water, it is beyond exhausting. 

So they go through all that trouble to lay their eggs and never even meet their babies. I feel bad for them. (On the other hand, raising babies is no walk in the park either, I'm a human Mom, I know.)

Which brings up another question: who takes care of the salmon babies? The answer is "the great nutrient cycle": as salmon grow in the ocean environment, they accumulate marine nutrients and store them in their bodies. After spawning and dying, they decay and release those nutrients, which then fertilize the water that feeds the developing salmon. 

So basically the babies eat their parents' remains. Wow.

This was a different kind of post for me, a science class of sorts. I hope you enjoyed it. I sure learned a lot. Check out how my fellow writers were swimming upstream and be sure to come back tomorrow for "High, low … in, out"  as of right now I have no clue how to go about that one!!

PS: Top Ten Thursday went live earlier today. We listed the top ten facts, myths or sayings we believe in, for example "he that hath, to him shall be given", "what goes around, comes around" or "there are a lot of vitamins in chocolate" ;-)