Blood meal is a powdered by-product from the slaughterhouse industry. Whilst bloodmeal used to be incorporated into home made groundbaits in the past it is a very high in nitrogen product and is commonly used as a fertilizer by gardeners so I would suggest that if it was put into any fishery in sufficient quantities you would soon have major problems with weed growth !
Most fish have a predatory instinct at certain times of the year so the blood taste would prove attractive to them but I can’t see it working all year round.