90 GEORGE B. RIGG 



The Alden banks in the Strait of Georgia north of the San Juan 

 Islands illustrate an unexplained condition in regard to kelps. 

 Throughout a large area, occasional clusters of kelps are found. 

 There are from 5 to 25 individuals in a cluster and they are much 

 entangled, as if their holdfasts were all very close together. A 

 somewhat similar condition is found at the south end of Guemmes 

 Island near Anacortes, Washington, and along the shore near New 

 Dungeness, Washington. The clustering is not so evident in the 

 two latter cases as in the first but in all of them the individual 

 kelps are vigorous enough but there are few of them. It would 

 seem that in these cases the tidal conditions are right but either 

 the depth of the water or the lack of suitable rocks for anchorage 

 may be the inhibiting factor. In case it should be merely the 

 absence of rocks, it seems possible that the yield might be increased 

 by adding rocks. A more intensive study of the conditions in 

 these beds is necessary before absolute conclusions can be drawn. 



In arriving at an estimate of the tonnage of the annual crop of 

 kelp in the region studied, the writer first estimated the number of 

 plants per square foot in the beds by placing a light wooden frame 

 4 feet square down upon the beds and counting the plants whose 

 bulbs were included. By doing this repeatedly, he estimated that 

 the thicker beds contained 1.25 plants per square foot. Fairly 

 dense beds vary from this down to 0.75 plants per square foot. 

 The weight of the individual plants was the next consideration. 

 It was found that mature kelp plants fresh from the water weigh 

 from 18 to 35 pounds. Knowing then the weight of the plants 

 and the number of plants per unit of area, one has but to determine 

 or estimate accurately, the length and width of a bed in order to 

 estimate more or less accurately the number of tons of kelp present. 

 By the above method the writer has estimated the annual crop 

 of kelp of the Puget Sound region including the American shore 

 of the strait of Juan de Fuca to be 210,000 tons. About one-half 

 of this is in the one bed at Smith Island. Since the plant is for 

 practical purposes an annual and its spores are matured in June, 

 July and August, it seems that the crop might be harvested after 

 July 15 without interfering with the next year's crop. 



