These particulat jetties don't stop the longshore transport of sand along the shoreline (at least not to a large extant; if they did large amounts of sand would build up on one side and not the other... look at historical photos this happens, but switches sides... Also sand goes inside the inlets during storms (a la Dredgine that will begin in late November in C-town pond)
The natural progression of tidal inlets is to stay open when there is enough exchange of water (tides and storm waves) and close during longer periods of fair weather; only to reopen during storms at the same or different location.
Basically these were installed in the 50's to keep the lagoons (ponds) open so that recreational and commercial boaters had access. If you want an idea of what it actually looked like before they installed the jetties, walk Moonstone beach after a storm (or backhoe) breaches Card's pond (much smaller scale than C-town et al. but a good proxie). The geology actually varies quite a bit more than people realize along the South shore..
Some interesting observations/notes.. Charlestown Breachway/Inlet is the only one of the south shore inlets that is not at the far eastern end of the barriers (against the rocky headland). At C-town this is the result of the underlying topography (likely an eroded glacial drumlin) that is"anchoring" the inlet here... with sea-level rise and landward migration of the barrier, the inlet will likely more East if left alone... I'm talking 100's to 1000's of years here, not our lifetime....
Also during storms or a large magnitude (a la Carol or 1938) Temporary inlets will open in the barriers (a big one is likely on the Misquamicut Barrier.. I have ideas where...
); forming as surge channels and then widening into inlets. My advisor and I have a debate about how long these would stay open if untouched, but regardless, the town of Westerly has a permit from the state to fil one if it opens... but my gut feeling says they would remain open for weeks - months maybe longer; but depends on storminess...
Ok, enough ranting and raving about Breachways and jetties...
back to work...
As far as landing fish there... I carry a gaff and a length of rope, generally I go down and get them with out the gaff, but dont fish them very often....