15 is the stage at BR I have always used. I don't fish old river at morganza much anymore but I did for a long time. What I always found is the spawn, especially sac a lait, is later there than in other places in Louisiana. That river water coming in from the Mississippi is C-O-L-D!!! I have caught sac a lait there full of eggs in April. I always started fishing there at about 25 feet and falling.