A year after eel fishermen in Maine earned their highest-ever pay rates for their catch, and as the global appetite for the snake-like fish continues to grow, the state’s annual baby eel fishing season is set to begin Friday. But while fishermen hope again to be paid more than $2,000 per pound for the baby eels — also known as glass eels or elvers — that swim into their nets this spring, some things will be different for the licensed dealers who buy them.