70 American Fisheries Society 



we could not handle ; and he finds that certain catfishes which we had 

 no use for in mussel propagation are the hosts of one of these quadrula 

 species. The Ictalurus punciatus is the natural host apparently of the 

 Quadrula pustulosa or "warty back" — a useful shell. He has found 

 young mussels on the gills of those fish and he has artificially infected 

 the fish with these mussels, and they have carried them for a number 

 of days. Just at this time he has not carried the matter far enough 

 to know the optimum number, but he has one catfish now that is carry- 

 ing 800. Of course the game fishes will carry from 1,000 to 2,000 more 

 of the other species. Undoubtedly this catfish would have carried 

 more if it had been loaded more heavily at the start. 



Dr. Townsend: I have been greatly interested in the Fish Commis- 

 sion reports touching this subject. The dependence of the mussel 

 upon the fish for its distribution is a very fascinating matter. I shall 

 watch the progress of work out on the Mississippi with a great deal 

 of interest. 



I am at present writing a report on the new method of pearl shell 

 cultivation on the west coast of Mexico. Last year I visited the great 

 pearl fisheries at La Paz where a Mexican company has been cultivating 

 pearl shell for two or three years. Entirely aside from the pearls that 

 sometimes turn up in the pearl oysters, pearl shell is a very valuable 

 commodity, being worth $300 or $400 a ton according to grade. There 

 is no doubt that the company has greatly increased the supply of pearl 

 shell in its locality, and while they refused to give me any 

 information as to their methods, I was allowed to go over the place 

 and form my own conclusions. I photographed the clusters of young 

 oysters, the trays, the crates of shells sunk in the bay, the zigzag canal 

 in which the crates are placed for the maturing of young, and altogether 

 made two dozen photographs which will show what the method is. 

 The promoters were harvesting the second crop of shells and appeared 

 to have a great quantity. 



The success of this work will be important to the ocean pearl shell 

 fisheries of the entire world. 



