Quick ?. How much to reduce stock

patsy3, Jan 15, 6:17am
I am making a crayfish stock to eventually do this recipe.
http://www.tapasbonitas.com/tapas_mariscos/Gambas_al_Ajillo_01e.php
How much to reduce the stock! by half or 3/4

knowsley, Jan 15, 6:37am
I read it as reducing by half.