Aquaculture, think agriculture but on the ocean, was a major component of Hawaiian subsistence. It is important to understand all the details of this way of life. Fishponds (loko) and fishtraps (hīnaʻi) are unique technological breakthroughs providing renewable resources to a thriving people living on a group of islands as far away as humanly possible from the mainlands of the earth. There were no alternatives, they had to make it work out here, and they did.
What remains of this way of life is being reconstructed by people who live here. Their ancestors are working with the fish to build an aquacultural future.
There are many details about fishponds that you can read online. The Kaloko-Honokohau National Historic Park is a font of resources.