source of alginic acid, kombu is still not in as great a 

 demand as are nori and wakame. 



Culture Techniques 



The cultivation, dating back 250 yr, is quite differ- 

 ent than that for nori and wakame. Kombu produc- 

 tion is increased primarily through the improvement 

 of available substrate and control of harmful 

 "weeds"" such as PhyHospadix, a marine sper- 

 matophyte. The latter is accomplished by dynamit- 

 ing to clear the PhyHospadix from areas suitable for 

 growth oi Laininaria. The former involves the plac- 

 ing of additional large rocks on the seabed on which 

 the plants may grow or, in some instances, using 

 artificial substrate such as various shapes of con- 

 crete. In addition, some cultivation has been done 

 using a hanging culture system (line and float). 



Problems 



Liimiiuiria is one of the many valuable marine 

 algae which have been plagued by the phenomenon 

 called "iso-yake"" by the Japanese which prevents 

 the plant from adhering to the bottom. Apparently, 

 the cause of this problem still has not been identified, 

 but it usually occurs in areas where the bottom is 

 covered with coralline algae. Some investigators 

 have advanced the theory that this results in a "des- 

 ert" condition with very little in the way of edible 

 seaweeds available to shellfish in the area. Thus, if 

 juvenile plants of Lam in aria and other such algae 

 begin to grow, they are grazed off rapidly. 



In this same vein, the .lapanese have determined, 

 as we have in California, that abalone are found only 

 where their primary source of food (brown algae- 

 kelps) is available (R. Burge, pers. comm.). In many 

 areas, the brown algae are completely lacking and, 

 thus, coastal waters in which abalone could grow, 

 are not usable for cultivation. A very large-scale 

 experiment is planned to begin in 1972 which will 

 involve the establishment of a large kelp bed in a bay. 

 if this is successful. 10 million abalone seed per year 

 for 3 yr will be introduced into the kelp bed. This 

 could lead to a new technique for expanding the 

 capability of the Japanese for producing both 

 l.diiiiiKiriii and abalone (Hisashi kan-no. pers. 

 comm.). 



Other possibilities being researched include the 

 development of techniques for cutting the normal 

 2-yr growth period to harvest down to I yr 

 (Hasegawa. 1972). This has been accomplished and 

 should lead to significant production increases. 



GELIDIUM AND OTHER 

 AGAROPHVTES (TENGLSA) 



Introduction 



Perhaps the most familiar algal extract to Ameri- 

 cans because of its wide use as a component of 

 bacterial growth media in both educational and med- 

 ical facilities, agar is used for similar purposes in 

 Japan. It is harvested for both domestic and export 

 purposes, including sales in the United States. 

 However, to meet the demand of the processors, 

 Japan must now import about 5,500 tons of the 

 12.000 tons dry weight used in agar production. 



Many red algae belonging to the families 

 Gelidaceae and Gracilariaceae serve as the source 

 of agar, but (Iclidiiim is the most important genus in 

 both Japan and the United States. 



Culture Techniques 



While much of the raw material for agar produc- 

 tion is harvested from natural beds, some artificial 

 propagation is practiced and has been for about 3(X) 

 yr. In the past, this has consisted largely of increas- 

 ing the available substrate by throwing large rocks 

 into the coastal waters in areas near existing beds 

 where spores will be sufficiently abundant to seed 

 the rocks. Other efforts to increase the supply of 

 agarophytes have included mechanical cleaning of 

 the rock surfaces, eliminating weeds (Ecklonici and 

 Eiscnia) from Gelidiiiiii beds, growing young plants 

 to harvestable size attached to ropes hanging from 

 floating lines, and, more recently, fertilizing the 

 coastal water in which the algae are growing 

 (Yamada, 1972). In this last effort, a lump of fer- 

 tilizer (in the form of urea, ammonium sulfate, or a 

 "nitrogen/phosphate mixture"") is placed on the 

 seatloor in the Gelidiiim bed and allowed to dis- 

 solve slowly. While this has succeeded on a com- 

 mercial scale, the economic feasibility of this prac- 

 tice has not been fully demonstrated as yet. 



Problems 



Gelidiiim and its relatives are among the har- 

 vested seaweeds known to suffer from the iso-yake 

 phenomenon. To date it has not been possible to 

 control the release of spores from Gelidiiim as has 

 been done with many other algae. Ability to do this 

 would make the establishment of nev\ populations 

 much more certain. Another potential problem is 

 Korea's growing production and export of agar 

 v\hich could create an excess and result in a profit 

 loss for Japan. 



100 



