This weekend they’ll be rockin’ in Ninilchik as Salmonfest moves into its sixth year. A crowd of mostly 20- and 30-something millennials and Generation Xers will be putting on the uniform of youth at this time and this place — jeans, Xtratufs and a hoodie. If it rains, and it always rains, they’ll dig a rain jacket out of their backpack. Several thousand will be dancing in the puddles late into the night in homage to being young in the North and to one of the most important reasons to live here — wild salmon.