My best guess would be:
It's not exactly clear what the answer is, but it very likely has something to do with:
flowing water, live a river.
Cry you may crook
As you gaze at my look
A crook is a body of flowing water; also, there's the common idiom "cry me a river" that this might refer to. But what are we gazing at?
A top notch runner
Diverts while I cover
Flowing water is sometimes known to be "running" water; when water meets an obstacle, its flow is diverted. But what is covering itself and/or taking cover?
I parch or I perch
But outwardly search
To be parched is to be thirsty, even dried up; a perch is a freshwater fish found in many flowing bodies of water. But what is searching?
A stretch and a spring
An ingenious thing
Again, a spring is another body of flowing water; many geographical formations are called "stretches" when referring to their length or breadth, as in a "stretch of land" or a "stretch of water", the latter being common for rivers and streams.
My answer is because
a salmon is a pink/orange fish that is often admired for its appearance, swims upstream thus diverting water around it, and searches for a place to make its nest when it reaches the uppermost part of the river it is swimming against.