The AquaHarvester is a building that is available in Tech Level 1. It costs 90 Carbon, and can be used by Utility Trawlers to gather food. It is essentially an aquatic version of the Farm that provides 715 Food, but cannot be upgraded.
AquaHarvesters should be built close to the Shipyard, to reduce the time it takes to drop off resources.
"AquaHarvesters function similarly to Farms — they produce a limited supply of food before they must be rebuilt — only AquaHarvesters are built on water, and not by workers but by Utility Trawlers that are built from your Shipyard. An AquaHarvester requires that a Utility Trawler stand by to extract food from it. Unlike Farms, AquaHarvesters cannot be upgraded to produce more food."