TABLE 4.

Comparison of PUFAs production by algae, higher plants and aquatic animals.

Item	Algae	Higher plants	Aquatic animals
Source	Genetic transformation for high-yield strains is relatively mature.	Very few high-yielding species	Fishery resources are limited.
Production	Production throughout the year, not limited by raw materials and origin.	Cultivation is affected by climatic conditions.	The PUFAs varies with the species of fish, season, geography, and fishing time.
	The cultivation and the production quality are relatively easy to control.	The yield and content may be affected by the environment and management.	The living environment of fish is easy to accumulate pollutants.
Harvesting & Extraction	Relatively difficult, and some algae need breaking the wall.	Relatively easy.	Relatively easy.
Purification	Relatively simple. Relatively higher content. Relatively easy enrichment.	Relatively simple. Relatively higher content. Relatively easy enrichment.	Contains a large amount of other saturated and low UFA. Relatively complicated.
Quality	No cholesterol, no fishy smell, no pesticides and heavy metal ion pollution; product characteristics are stable.	No cholesterol, no fishy smell; stable product characteristics. Some crops may have pesticide residues.	Relative higher cholesterol and often has a fishy smell, heavy metals and other environmental pollutants.