The Collaborative International Dictionary of English v.0.48:

Botargo \Bo*tar"go\, n. [It. bottarga, bottarica; or Sp.
   botarga; a kind of large sausages, a sort of wide breeches:
   cf. F. boutargue.]
   A sort of cake or sausage, made of the salted roes of the
   mullet, much used on the coast of the Mediterranean as an
   incentive to drink.
   [1913 Webster]