82 American Fisheries Society 



On September 30th, 1918, approximately 11,000 of the live 

 juveniles were returned to this pen, which was resubmerged in 

 the lake to a depth which would enable the young mussels to 

 escape freezing. Certain ones were measured carefully and 

 numbered, and their dimensions recorded. These mussels were 

 not disturbed until September of this year, when the pen bottom 

 was raised and its contents examined. 



The average growth of the mussels during the second year was 

 found to be 16.72 millimeters. Only 80 live mussels were recovered, 

 the largest being 37.0 and the smallest 6.7 millimeters long. An 

 attendant circumstance was that hundreds of the second season 

 mussels had been eaten by a turtle or bottom-feeding fish. A quart 

 jar of shell fragments, hinges and umbones, showing first season 

 shell plus part of the second season's growth, was recovered. 

 These fine, strong shells had been crushed by the jaws of a mussel 

 devouring animal. A count of hinges and pairs of umbones 

 showed that 2,085 mussels had been destroyed in this manner. 

 Thus the total yield of second year shells should have been 

 approximately 2,165, which would still be less than one-fifth of 

 the number of first season juveniles replanted in September, 1918. 



Frontenac Enclosure 



During July, 1918, infected fishes were confined in the enclosure 

 at Frontenac, which was 10 feet square and had sides from 6 to 

 9 feet high; 46 of the infected fishes dropped young mussels in 

 the pen. Due to the lateness of the season, the bottom of the 

 pen was but partly examined on November 11th, 1918, and no 

 exact estimate of the number of juveniles was obtained, although 

 several juvenile luteola were recovered which were from 4.0 to 

 2.5 millimeters long. These were returned to the pen, which was 

 resubmerged. 



On September 12th, 1919, 480 second season luteolas were 

 recovered, the largest 30.8 and the smallest 7.4 millimeters in 

 length. The average second season's growth was 19.35 millimeters. 



Stockholm Enclosure 



Infected wall-eyed pike placed in the enclosure at Stockholm 

 on August 6th and 14th, 1918, were still carrying practically the 

 original number of glochidia on their gills when released on 



