The Collaborative International Dictionary of English v.0.48:

Siscowet \Sis"co*wet\, n. [OF American Indian origin.] (Zool.)
   A large, fat variety of the namaycush found in Lake Superior;
   -- called also siskawet, siskiwit.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Siskiwit \Sis"ki*wit\, n. (Zool.)
   The siscowet.
   [1913 Webster]