I did NOT take this photo (I screengrabbed it from the BBC video)
Are we like the salmon or a trout?
The salmon are anadromous (migrate). They are born in fresh water, migrate to the ocean, then return to back home to fresh water. After leaving the fresh water, just before entering the salt water, their body chemistry changes, allowing them to live in the different water environment. The salmon spend about one to five years in the open ocean where they gradually become mature. The adult salmon then return back up their natal stream to spawn. While hard to believe, tracking studies show that these fish return to the exact spot where they were born. This homing behavior has been shown to depend on their olfactory memory. (smell.. the ability to discern). Not many salmon eggs make it to maturity. Many are lost.
The trout however are content to stay where they are ... they are called "resident". They possible like the security of the pleasant, calm easy water.
In order for the salmon to return back to where they came from, they much swim upstream.. against the current. It is a difficult and strenous requiring an unrelenting force pulling them back. Trout are mainstream fish and they rarely swim against the current...content they are gradually being pulled downstream with the rest of the flow or stay in pools (not really moving up or down stream).
For the salmon, swimming against the the fast moving current is not their only challenge. Unfortunately, there are small waterfalls that they must over which requires these fish to jump out of the water (their security and environment) in order to get to the higher level of water. The Bears are very keen and smart, they stand with open mouth ready to eat the salmon as they attempt to jump past these hairy "gatekeepers" of the higher water. Many salmon do not make it past and are eaten alive.
There is beauty is seeing the salmon pierce the water, jump past the bears into the fresh water of their origin.