No, salmon are not endangered world-wide. For example, most populations in Alaska are healthy. Some populations in the Pacific Northwest are much healthier than others.
There are seven species of Pacific salmon. Five of them occur in North American waters: chinook, coho, chum, sockeye, and pink. Masu and amago salmon occur only in Asia. There is one species of Atlantic salmon.
Certain populations of sockeye salmon, coho salmon, chinook salmon, and Atlantic salmon are listed as endangered. Sockeye salmon from the Snake River system are probably the most endangered salmon.
There are many reasons for the decline in salmon populations. Logging an area around a stream reduces the shade and nutrients available to the stream and increases the amount of silt or dirt in the water, which can choke out developing eggs.
Most salmon species live 2 to 7 years (4 to 5 average). Steelhead trout can live up to about 11 years.Learn more:Salmon (NOAA FishWatch)
Some things we can do to save salmon are to protect their stream habitat, help restore streams that have been damaged, reduce fishing, and help find ways to increase salmon survival through the dams. 
A number of studies, involving at least five species of salmon, have found genetic differences between hatchery fish and wild fish that make the hatchery fish less successful for reproducing or rearing in natural streams.
Most Pacific salmon can be seen migrating from spring though fall, depending on the species.
Salmon come back to the same stream they were 'born' in because they 'know' it is a good place to spawn and they won't waste time looking for another stream with good habitat and other fish to spawn with. 
Salmon first travel from their home stream to the ocean, which can be a distance of hundreds of miles. Once they reach the ocean, they might travel an additional 1,000 miles to reach their feeding grounds.Learn more: