Why?
The goals of the Salmon change when they reach mating age. Now they don’t need to survive in the ocean, they need to make sperm/eggs and survive the long trip to their birthplace. This trip is through fresh water lakes and rivers. That is a very different environment from the ocean. They will need to jump/swim up waterfalls. They will need to avoid predators, but very different ones than they faced in the ocean.At the end of their journey they will mate and die.
Because the goals and environmental pressures change so much the Salmon must also change to meet those new challenges. If they didn’t they wouldn’t be as successful in reaching their final destination and making more Salmon.
How?
Just like humans, hormones trigger biological changes. The change to fresh water also triggers changes and a countdown clock. The changes use a lot of energy, as does their trip and mating. Their body will literally consume itself to make the changes and meet the challenges it needs to so that the salmon make it home to mate.
In case anyone was curious
If there’s one person on lemmy that I trust for my aquatic animal info, it’s sharkfucker420
I would also trust them with knowledge on marijuana
But why do pacific salmon go through all these changes and die after mating only once, while Atlantic salmon can do the same thing but survive to mate many years in a row?
Is it all salmon species? I stumble upon dead salmon after spawning all the time during field work and I’ve never seen one that looks like that. They usually look like the top photo.
This is just a pink salmon aka a humpy. Other species of salmon get the big overbite - called a kipe and big doglike teeth and usually more red coloration.
Same
Everything I know about salmons is thanks to The Chemical Brothers
are they still salmon colored?
That thing looks like a fish skeksis.
Salmon 1: “Oh gosh, i’m out of the water. I cannot breathe. If this continues for much longer I will surely perish. What a sad state of affairs.”
Salmon 2: "YOU FCKFACE YOU CANNOT KILL ME BY TAKING ME OUT OF WATER I WILL SUCK THE MOISTURE OUT OF THE AIR THEN SPIT BLOOD INTO YOUR SOUL, AUUUGGGHHH! SEX!!! SEEXXX!!! I NEED SEEEEXXXXXXX!!!"
splatoon moment
Do da humpty hump