I'd just like to add that Mataitai are not predominantly designed to be a stock replenishing tool.
It is a result of honouring/ acknowledging (choose which you prefer) the Treaty of Waitangi and is carried out by different legislation (including Fisheries Act). Matatai is an area of water; rohe moana, that is of special importance (in the way of customary fishing) to iwi/hapu and allows the iwi to manage that area.
The iwi has to have their rohe moana gazetted, this can be difficult to do, particularly where a lot of iwi/ hapu have overlapping areas of significance (particularly east cape) and cannot come to an agreement about their boundaries.
Marligator is right, comms are nearly always automatically excluded from fishing in a mataitai but the iwi can create by-laws to allow certain methods back in. These by-laws can also be created around recreational catch. They can't however choose that only Maori can fish there but no one else, but yes would be able to make it customary authorisation only.
I'm not too sure if any mataitai has actually managed to put in place their own recreational by-laws though... Would be interesting to know.