People talk about Klamath River salmon, or Rogue River salmon, as though every river has its own unique species. But isn't a salmon a salmon? So they die out in a particular river—it's not like they're extinct. Can't we throw some new salmon in there and call it good? —Animal Logic
Cut the salmon some slack; their love lives are among the dullest in the animal kingdom. Females lay their eggs in a hole. The males come along and fertilize them. It's like swimming 900 miles upstream to masturbate over a used tampon.
There are, in fact, scientific reasons for wanting to preserve individual runs of salmon besides "they're salmon, and you're an Oregonian." (That said, in the future please employ the customary tone of hushed reverence when speaking of our mighty Fish-God.)
"Because every river system is different, the salmon in those rivers are different," says Sam Mace, Inland NW director of Save Our Wild Salmon. "Their genetics are special. You couldn't throw Willamette River salmon in the Snake and expect them to make the journey."
It's true that losing one particular run of salmon is not the same as losing a whole species, but their populations need as much genetic diversity as possible if they're going to survive the rigors of a changing climate. Think of it as losing an arm in a world where someday, every car may be a stick shift.
The loss of a particular salmon run doesn't have to be permanent, though; Mace says there are cases of salmon returning to rivers once the stressors that drove them away (usually hydroelectric dams) are removed. Salmon claim this is why they favor nuclear power, though most observers believe they're just looking for an excuse to mutate to enormous size and have the last laugh.