'Upena ku'u (gill nets) were used by ancient Hawaiians to catch schools of fish which . Nets measured between 30-90 feet long with mesh holes from 1.5 to 2.5 nches square. The depth of the net ranged from 6.5 to 10.5 feet and floats or sinkers were attached to the net as needed. Wooden floats tied to the top of the net and stone weights tied to the bottom, to hold the net in place and not to get tangled.

A hanging gill net, called the 'upena ho'olewalewa, was set during high tide and stretched between two points where fish run in shallow water. One or two persons worked the net passing it backward and forward to remove fish as soon as they were caught inthe mesh. This was only done at night and they were also left overnight and fish cuaght intheir gills were removed in the morning.

Another method 'upena 'apo'apo used the same net. Fishermen encirlced around a place where fish were seen or might likely be with a net and then enter the area and beat the water to drive the fish into the mesh.

Fishermen set gill nets near the shore when the seas were calm. Big waves might drag the gill net onto the coral reef and it might get caught or ripped.