Juro is the resident Spey guy around here. He was for some years deprived of the Cape Cod striper experience and had to make do with something called steelhead that live somewhere in the northwest. He picked up some Spey tactics and has toyed with the concept here.
As to the herring run, I'm certain that it predates the canal. I have a map of the area from 1879, and the Herring Pond that the run feeds had an outlet in Buzzard's Bay.