The Collaborative International Dictionary of English v.0.48:

Saithe \Saithe\, n. [Gael. saoidheam.] (Zool.)
   The pollock, or coalfish; -- called also sillock. [Scot.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sillock \Sil"lock\, n. (Zool.)
   The pollock, or coalfish.
   [1913 Webster]