Ok so question for the poster how accessible are these spots, example could you view the spot if you covered it with particles. how clear is the water etc....., can you bait those spots regular
If you get to ticks to the above question, find a couple of points in line with markers from where you can cast from, apply a couple of kilo's of hemp with a mix of small halibut pellets every day for about 2-3 days before you are due to fish, if the fish are visiting and munch those spots will start to be become very clean, when fishing apply same loose feed and pop a bait in.