The most important aspect in developing a productive seaweed farm is the site selection. Farmers look for good water motion that replenishes nutrients, keeps the seaweed clean and prevents extreme fluctuations in temperature, salinity, pH and dissolved gases. The farm shouldn’t be too exposed to strong winds, waves and currents either. The exposure, location, water depth and substrate beneath the farm will determine the farm design and its cultivation method.
Explore Site Selection by Species
Undaria naturally occurs in the open sea, usually in the lower intertidal zone up to 18 m depth. Salinity levels between 27-33ppt are preferred at an optimal growth temperatures between 5-15°C.
Suitable site conditions:
- Water depth between 10 and 40 metres (preferably 20-30 m)
- Water velocity between 0.2 and 1 m/s (preferably 0.6-0.8 m/s)
- Water temperature between 2°C and 20°C
- Transparency in the water column above 3 metres
In South Korea the majority of Undaria farming takes place in the Southern coast, where conditions are typically more sheltered. We visited farms in Jeonnam district and the North coast of Busan which together almost account for 99% of national production of Undaria.
In Japan, we visited farms in the Sanriku prefecture, which is the most famous and largest Undaria farming region, responsible for 74% of total Undaria production in Japan. This East Coast of Japan, is characterized by open sea conditions with strong tidal currents.
In China, Undaria is farmed in most of the coastline of the Shandong and Liaoning peninsula, where Dalian is by far the most productive region and site conditions are mostly expose.
In Southern China and South Korea, Undaria is often farmed as fresh feedstock for Abalone farms and located in close proximity to them. It is typically farmed interchangeably with Saccharina.
Since the farmable area is publicly owned, prospective farmers must obtain a concession or licence from the government before they begin operating. In China and South Korea it is getting more difficult to obtain permits for new farms or farm expansions, as the maximum carrying capacity has been reached in most established locations. In South Korea and Japan it is mandatory to be in a farmers association in order to receive a permit.
In China, farm sizes are not usually measured in hectares, but rather in MU (1 ha = 15 MU) or simply by the length of cultivation lines. In Japan and South Korea, the measurement of farms in length and amount of culture lines is more common than hectares as a metric.