The Collaborative International Dictionary of English v.0.48:

Sea trout \Sea" trout`\ (Zool.)
   (a) Any one of several species of true trouts which descend
       rivers and enter the sea after spawning, as the European
       bull trout and salmon trout, and the eastern American
       spotted trout.
   (b) The common squeteague, and the spotted squeteague.
   (c) A California fish of the family Chiridae, especially
       Hexagrammus decagrammus; -- called also spotted rock
       trout. See Rock trout, under Rock.
   (d) A California sciaenoid fish (Cynoscion nobilis); --
       called also white sea bass.
       [1913 Webster]