Steve, I assume you to be relatively local.
I used to fish the Newhaven breakwaters quite a lot some years ago, Seaford Beach occasionally usually by the Buckle but only at night. It always seemed to be alive at anytime of the year with little Pout.
Due to the problems with trawling etc I prefered to fish the breakwaters where year round you were certain to catch, just be adaptable.
Pros - Summer days float fishing for Gars & Mackeral with strip or sandeel on light gear or if prepared to chance it Mac head ( with guts attached) close to the rocks either at the inside end of the west arm or outer close in from shore side (imposible to land big bass otherwise)also use live prawns. Eels if you like 'em. Scad under a lamp at night on float gear, Mullet & Bass up the river. Allsorts really!.
Early winter whiting trips, late winter flounders. Proper Anglers? facing adverse conditions, the craic.
By the way I hooked but lost a Turbot the size of a large dusbin lid on the East breakwater; casting out too the east 3 hook paternoster strip bait, there were about a dozen witnesses!.
Against fishing the breakwaters - Bloomin crab pots, ferries, rocks, other anglers, general public/ kids etc, smelly (toilets are a long way a way, but its fishing people that do it!). Oh yes, the west breakwater can be bloody dangerous in bad weather!.
All in all & as bad as it can environmentally, the breakwaters are worse then some but much better then most.