The starting gun for this years salmon run has gone off! The rains have started.The salmon are on their way to their natal streams.Each will sniff out their natal stream.Each stream has many soluble minerals in it. Each stream has a unique mineral finger print.
As a parallel each key has a unique cut to differentiate it from another. The same with each stream.Each stream has unique trace minerals in it. This unique mineral marker was imprinted into the salmon when it was born in that particular stream. Each salmon is like a blood hound sniffing it’s way back to it’s natal stream. Think of it like a huge highway with millions of salmon all swimming together.When the salmon smells it’s stream It simply ramps off!
Once it finds it’s stream It’ll “stage”.All that means is it’ll stay out front of the stream breathing in that fresh water. The fresh water coming from the stream begins to change them.This triggers hormonal changes.The male salmon will grow large hooked jaws.They change like Dr.Jekyll & Mr.Hyde. They change into Mr.Hyde! Once they begin to change they go upstream to check things out.They head to the salmon party!
They move upstream during high tide & hunker down in the deep pools during low tide.They know it’s dangerous to move from hole to hole during low tide.The bears are waiting to pick off the dumb ones.The ones who try to make a run between deeper holes during low tide are invited to dinner. Once they get above the tide line they are on their own.No more protection.They want lots of rain so the streams fill with lots of water.Lots of water means deeper waters. Which means protection from the bears grabbing them.
One of the problems bears have is seeing the salmon.So they like these pedestal like rocks to stand on.They can look down & see the salmon swimming.A rookie bear will jump in when he sees the salmon swimming about.A smart bear will wait for low tide when there is less water around.That way the salmon has fewer options to escape!
The male salmon begin to fight with each other.They will find a female & swim beside her.If another male comes too close,that male will attack! I once let a underwater camera go downstream to record the spawning salmon.A male didn’t like the looks of my camera & attacked it.
Once the female is ready she’ll dig a rut (red) in the gravel.She’ll lay her eggs & the male will release his milt from upstream.The eggs are than covered back up with the gravel.The eggs have a semi permeable membrane that allows oxygen to pass through.During the winter the fresh oxygen will keep them alive.This is when they are imprinted with that streams unique mineral signature!The eggs are vulnerable to many factors.Other fish coming into the stream for a snack,temperature,PH,DO (dissolved oxygen).
Streams that have been logged down to a streams edge will have lots of sediment being washed down the hillsides into that stream.That sediment settles on top of the eggs, cutting off the oxygen. Which in turn kills the eggs.
So……..say instead of 100,000 salmon heading out of that stream to that big highway out to the ocean,there may only be 10,000.So in 4 years time that returning population will be far smaller than normal due to that sediment. Thats why clear cutting should never happen near a salmon stream.
Btw,that 10,000 will be reduced even further by predators while they are out in the ocean for 4 years & remember that when they come back fully grown they have to get through that bruin gauntlet as well!
Life as a salmon is tough! Once they lay their eggs & release their milt,they die.They fall like snowflakes to the bottom.This is when bears reach under the water (like a racoon) & grab leftovers. When the first big rain happens all those dead salmon carcasses are swept downstream by the increased current.All the birds & crabs are waiting out front with smiles on!