You don't need the pump in the sump area. With the plug out of the sump area the boat will self bail at rest and underway, however if you had a substantial amount of weight in the stern such as maybe 3 big anglers gaffing a large tuna, for example, water could fill the sump area and raise up onto the deck surface and get the anglers feet wet. So to avoid this scenario the sump area has the move-able pump. Albury Brothers boats built in the Bahamas are not equipped with this sump pump as standard in keeping with their less-is-more build philosophy, for example.
You can't see the scuppers in that photo. Look at the transom photo.
Its a great set up. There is also a plug in that bilge section that you can pull and run with it out. Everything drains to that section, water, blood, scales..etc, the pump does what its intended for if you desire to use it..and can also be lifted out with its mounting plate on top of the deck if need be to clean that area... or there is a switch to disable it. Totally Self bailing, plug is at water line..deck is above that, and there is also a bilge plug, underneath that, but I never had 1 drop of water below the deck. Here are a few pics showing both the drain plugs, and relationship of the waterline as the boat sits in the water. Id rather have a system that I can see, have easy access to, vs having to go below a deck, or through a inspection plate to check if my bilge is working or not. Jeff