"hundreds of tribulations"
OK, I exaggerated a bit!! Maybe not hundreds right off the top of my head but--

Bad spawning beds
Preditors in the river like Mergansers
Open sea
Peditors like seals, whales, other fish
Lack of feed during their growth cycle
Polution
Gill nets (both Indian and non-indian)
Trawlers
Purse Seins
El Nino
Foreign fleets
Interception on their way home, you get the picture
They just do not have much of a chance.

We should limit the fish take and protect them first, let the price of Salmon go up like gas and the users like the Indians will still make money, which is what it is all about.