hi Tonto, welcome to SAI
all i know is that there are definitely bass and sea trout that patrol the edges of the lough, especially on the south side near the very mouth of the lough - it is ideal territory.
i took part in a fly-fishing bass competition a couple of years ago where im sure there were 80 men lined along that stretch of shore, all fly-fishing, but only about 6 fish were caught all day

- so they are hard to get on the fly anyways so i suggest spinning or bait if you want to target either species.
i heard mackerel come in to casting distance during the summer off grenore, it may be a bit early but u never know..
i have never bait fished the bottom there but there is plenty of clean ground all around the lough, im sure its definitely worth a go for flatties, cod, coley or whatever.
hope this helps, good luck. beautiful part of the world!!