What is a fish (Coregonus ferus) of North Wales and Northern Europe, allied to the lake whitefish; -- called also powan, and schelly. [Written also gwyniad, guiniad, gurniad.] called?

gwiniad — A fish (Coregonus ferus) of North Wales and Northern Europe, allied to the lake whitefish; -- called also powan, and schelly. [Written also gwyniad, guiniad, gurniad.]. (Webster's 1913.)