How often does he get baths? While it may not slow the shedding down, I have found that it will deposit a lot of the hair in the bathtub, and not on the couch LOL!
I would try a different food and see if that helps as well. A friend of mine had a lab that started shedding like mad last fall. Vet said it was allergies and they determined it was the food he was feeing him. Has fed him the same food for years, but either something changed in the food, or the dog developed some kind of allergy out of the blue. the vet said more than likely something in the food.
either way, he switched and the dogs coat is remarkably smooth now and the dog isn't itching or shedding nearly as much. I just asked him last weekend how he was doing because of the warmer weather and he said no changes. all is good.