01 Emerge from gravel
Alevins live on yolk in the redd.
Operating a salmon life is a loop: sense, decide, act, and stay inside an energy and legal envelope.
Steps are type-level -- hunt, migrate or spawn -- not a promise that every individual follows the same film sequence.
Principles
Energy in, work out
Marine fat built on plankton and forage fish, then spent on the upstream fast. Semelparous Pacific bodies become the forest fertiliser.
Information before motion
Natal-stream olfaction is the famous sense. Polarised light and magnetite help the ocean leg.
Replacement rate
Slow breeders (whales, apes, albatrosses, tigers) cannot outrun a short political cycle. Fast clutch species still fail if the nest site vanishes.
Place is part of the phenotype
A salmon without its lake, ice, anemone or gravel is a different, usually failing, animal.
Human systems are now habitat
Quotas, feeders, reserves and films rewrite survival as much as weather. Dams, warm water, and a hatchery that smells like a factory. Climate-warmed rivers close the adult run before the gravel is reached.
Diagrams
Salmon forage / hunt loop
Sensesense
Orientmove
Strikeact
Handlehandle
Spawninvest
Recruitleave
Salmon life-cycle loop
Hatchstart
Reargrow
Movemove
Feedlearn
Spawnbreed
Die or repeatend
Life-cycle steps
02 Rear in fresh water
Weeks to years depending on species.
03 Smolt and go to sea
Gill ion pumps reverse for salt.
04 Feed in gyres
Ocean years set the return mass.
05 Home by smell
Adults climb, leap and stall at ladders.
06 Spawn and often die
Redds rewrite the next cohort; carcasses rewrite the trees.
Hard limits
Physiological envelope
Dams, warm water, and a hatchery that smells like a factory. Climate-warmed rivers close the adult run before the gravel is reached.
Place dependence
Without the breeding site or forage pulse, brochure behaviour is theoretical.
Human and legal limits
Quotas, listings and trade rules now bound real populations as tightly as weather.
Keep exploring
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Overall 36