242 FISHERY INDUSTRIAL PRODUCTS 



good sources of vitamins, among which are included beta-carotene (pro 

 vitamin A); various B vitamins — such as thiamin, riboflavin, niacin, 

 pantothenic acid, and vitamin B12; vitamin C; and vitamin D. 



Problems in Utilizing Seaweeds 



Supply. To the casual observer, nature seems to be of unlimited bounty. 

 Viewing a large bed of seaweed, he gains the impression that the supply 

 is endless. He quickly learns otherwise, however, when he attempts com- 

 mercial exploitation. As we have seen, a number of factors, such as the 

 requirement for light, limit the growing area for seaweed in most localities 

 to a relatively narrow strip of coast line. Other factors, such as the size 

 of the seaweed, its content of the desired constituents, or its possible 

 tendency to grow intermingled with less desirable species, impose further 

 limitations. A fundamental problem in the seaweed industry thus is to 

 obtain a continuing source of supply sufficiently close to the processing 

 plant to keep the cost of transportation within economic limits. 



Harvesting. Not only are seaweeds usually found along a narrow strip 

 of coast line, but even in this limited area, they often grow in places where 

 they are difficult or even dangerous to harvest. With the notable exception 

 of the giant kelp, which will be discussed later, their habits of growth often 

 do not permit them to be harvested easily. 



Hand harvesting is the rule for most species. For this reason, the devel- 

 opment of a mechanical harvester by the Scotish workers is of particular 

 interest. They have invented a motor-driven steel-mesh belt with short 

 hooks attached. This device can be operated from a vessel as it moves 

 over a bed of seaweed. The German workers have developed an angle 

 scythe for cutting reeds in pond fish culture. This device may lead also 

 to better methods of seaweed harvesting. 



Uses of Seaweeds 



Seaweeds are sources of food, fertilizer, and chemicals, with chemicals 

 being predominant in importance. 



Food. Human Food. Although seaweeds are used extensively for human 

 food in the Orient, particularly in Japan, these products are not very 

 popular in Western countries. On a dry-weight basis, seaweeds generally 

 consist almost two thirds of carbohydrates, such as cellulose, which 

 Western people do not find digestible. In the United States, the main 

 varieties of seaweed used for food, principally as relishes and as thickeners 

 in soup, are Irish moss, dulse, and purple laver. 



Owing to possible use in space travel, algae for feeding humans are of 

 increasing interest. Powell and co-workers^ found that using a mixture of 



