Summary paragraph for this part

i For years, scientists have speculated as to how salmon find their way back to their natal streams. One widely accepted hypothesis states that when salmon are young, they imprint the pattern of Earth's magnetic field where they are born. Years

$5$ later, this memory serves as an internal GPS$.$

The last stretch of a salmon's journey is the most dangerous. The closer it gets to home, the more perilous the trek becomes. Sailors used to call salmon the leaping fish. They launch their

bodies over entire waterfalls, and sometimes land directly in $10$ the mouths of waiting bears.

Today the Chinook salmon is on the endangered species list. Fluctuating sea temperatures, man$-$made dams, and declining water levels make the journey home nearly impossible. Every spring, fish biologists report increasingly high numbers of $15$ salmon carcasses in local rivers. According to a study conducted by scientists from the National Oceanic and Atmospheric Administration, Oregon salmon are slowly being pushed north toward Alaska as a direct result of climate change. As ocean temperatures continue to rise, salmon will seek out waters that $20$ better mirror the conditions to which they're adapted. In time, some species of salmon may disappear completely from the $Pa$ cific Northwest.

part $6$