What would most likely happen if number of salmon decreased

Any forms of predatory or parasitic life may decrease, or even vanish! As then would the creatures that survived off of these organisms. I would be able to go on for a while about the different organisms of all sizes that would vanish and how they would cause other species to be affected.
Salmon are VERY important to the food chain!

Hope this helps!  

Idont see a question here

The name of the instrument that the scientist uses is called a microscope.a microscope is used to view objects which is not visible to the naked eyes