For the Pot monitor

Right, this is for your potty members, what are they for?

Exciting .. a new pot

My guess is something to do with prawn or yabbie farming.

Might be a possible clue on the gate??

I'm going with Pacific Oyster farming

Paul has it right, they grow the baby Pacific oysters for Moana Sea Foods in a hatchery in Nelson at the NW corner of the South Island.

https://www.bing.com/videos/search?q=growing+pacific+oysters&docid=607998324017681108&mid=7E4E8FEB4756F476912D7E4E8FEB4756F476912D&view=detail&FORM=VIRE

The video shows how they produce the baby oysters, but does not mention that oysters naturally anchor to rocks dead shells or some other hard surface at the spat stage only. In the nursery they introduce a chemical that stops this so from then on the oysters cannot attach.
The oyster farms get the baby oysters at fingernail size and put them in mesh socks inside the baskets I showed. The baskets are then put on racks that only dry out near low tide, and are left until marketable size.

Mussels are different in that they can move and anchor at any stage, I have had small mussels move around my aquarium looking for the right conditions.
The mussel spat washes up on beaches in the north of NZ, is collected and allowed to attach to string, the string is then wrapped around loops of rope which hang below a line of plastic buoys anchored at each end to large concrete blocks mostly in sheltered coves or inlets. The mussels are mechanically stripped by a barge, washed and hand sorted for undersize ones then packed in woolsack sized bags.

The oyster racks and more so the mussel farms are a huge source of food and habitat for fish, the mussel farms when processing mussels have schools of fish, mostly snapper in the dirty water down current and often tow a barge behind with fishermen on board. Private boats are allowed to tie up to the buoys as long as they do not get in the way of work.

I thought of a chum basket for fishing at anchor.
In Scotland on the salmon farms,they are introducing Wrasse that are shipped up from Cornwall to eat the lice that get on the Salmon.

Everyday a school day! Fascinating info Rhod, introducing a chemical doesn't sound great to consumers!
Whereas natural measures such as those Wrasse sounds far more a marketable approach