The Collaborative International Dictionary of English v.0.48:

Syle \Syle\, n. [See Sile a young herring.] (Zool.)
   A young herring (Clupea harengus). [Also written sile.]
   [1913 Webster]

         But our folk call them syle, and nought but syle,
         And when they're grown, why then we call them herring.
                                                  --J. Ingelow.
   [1913 Webster]