1 66 BULLETIN OF THE BUREAU OF FISHERIES. 



in locating the troughs. The troughs were 12 feet long, i foot wide, and 8 inches deep, 

 painted with asphaltum, and each had its independent inflow from a common screened 

 supply pipe in the pond. The bottom of each trough was covered with fine sand to a 

 depth of about one-half inch. 



Records were kept of the progress of the larval mussels through the process of devel- 

 opment, and when they had reached that stage when they were ready to drop from the 

 fish, counts on the fish gave a close approximation of the number dropped in the trough. 



The results of the experiments the first season were quite meager, as only 7 young 

 of the Lake Pepin mucket, Lampsilis luteola, varying from 6 mm. to 17.8 mm. in length, 

 and 4 of the mucket, L. ligameniina, with an average length of 2.5 mm., were reared. 

 However, in case of the mucket the results were very encouraging, as it marked the first 

 instance of juveniles of this species being artificially reared to this size. 



During the season of 191 8 greater results were obtained with the Lake Pepin mucket, 

 the young mussels being successfully reared in four troughs. In one trough a count of 

 746 was obtained. The experiments with ligameniina yielded negative results, though 

 a lack of glochidia for infection greatly handicapped the work with this species. 



The results in 191 9 were still more gratifying. Young Lake Pepin muckets were 

 obtained in each of five troughs planted with this species. In one trough 2,008 were 

 counted at the end of the season, these little mussels varying in length from 9 mm. to 

 17.5 mm., the growth comparing very favorably with that made by the young of this 

 Species in their natural habitat. In a trough devoted to the river mucket, L. ligameniina, 

 a total of 565 were reared. These little mussels varied in length from 5 mm. to 8.5 mm. 

 In a trough planted with the yellow sand-shell a count of 2,006 was obtained at the end 

 of the season, the young mussels varying in length from 5.5 mm. to 12 mm. The result 

 of this experiment is highly interesting, in that it is the first record of the artificial rearing 

 of this very valuable species in any quantity. 



The 746 young luieola reared during the summer of 191 8 were carried over the winter 

 in a shallow crate bottom 5 feet square and 8 inches deep, submerged in one of the earth 

 ponds. During the summer of 191 9 an inventory of the crate bottom gave a count of 

 238 young mussels, a survival percentage of about 32 per cent. 



The method of artificial rearing of young mussels, as detailed above, denotes a 

 distinct departure from the methods previously used and gives the operator complete 

 control of conditions throughout. The results of the experiments have been such as to 

 justify the employment of the method on a much larger scale in future, and plans are 

 under way for materially increasing the facilities and equipment. Certain phases of the 

 work need further study and amplification. Additional information on the possible 

 enemies of the young mussels in the troughs is needed; a study of their food should be 

 made; it should be learned if artificial feeding is practicable; and further experiments 

 should be made to determine the most favorable bottom material for the troughs, 

 whether fine sand alone, or sand with a slight admixture of silt, etc. The present indi- 

 cations are that fine sand is the most desirable bottom material. 



In summary of the topic of the culture of fresh-water mussels, it may be stated that 

 the results of many experiments conducted under diverse conditions demonstrate that 

 the valuable Lake Pepin mucket can be reared in quantities, under conditions of control. 

 Sufficient success has been attained with other species to warrant confidence that, with 

 them also, methods of securing constant results will be found. 



